It is assumed that you will prevent sheep totally destroying young trees, or eating the bark of older trees.

Grass under fruit trees
Grass competes with your fruit trees for soil nutrients and for water. The most critical issue is water. Some fruit and nut trees are deep rooted and can withstand drying out better than others.

Relatively grass tolerant fruit and nut trees
Walnuts, macadamias and pecans can 'more or less'  look after themselves in a dry year (except in prolonged droughts on sandy or stony dry soils and with deep watertables). Some fruit trees tolerate grass competition for water until summer really sets in, and then they can suffer in a dry year. These are stonefruit such as plums, peaches, and apricots. They fruit relatively early, and with luck, fruit are fully formed by time of water deficit. I am not suggesting that you can  ignore the need to avoid water stress in stone fruit trees - but arguing that that in most years, early and mid season stonefruit varieties on soils with an average water holding capacity will tolerate grass to the trunk and still give the home fruit grower an average crop. Late season peaches and plums should ideally be mulched, or have the vegetation sprayed out before the soil loses much of its retained water with the onset of drier conditions around late spring/summer.

Relatively grass intolerant fruit and nut trees
Shallow rooted fruit trees, specifically citrus, casimiroas, apples on malling 9 dwarf rootstock - and to a lesser extent persimmons and feijoas - suffer badly if the surface soil dries out to any great degree. Casimiroas, in particular, will shed large numbers of set fruit if they are 'checked' by dry soil. Hazel nuts must have relatively moist soil in the growing season. You can let the grass grow to the trunk of these trees in the winter, but the sward must be sprayed out relatively early - probably by late spring at the latest, if soil moisture is to be conserved. If it is a wet spring then it can be delayed, but spring grass growth is so strong that any dry spell thereafter will quickly deplete the soil of its moisture reserves.

Irrigation
If you are lucky enough to have a bore and plenty of water available over summer, then you can use it in late spring when needed to extend the period before you need to spray under your trees.

Sward types
Ryegrass clover
Larger home orchards on 'lifestyle blocks' most often have the home orchard planted into existing pasture of perennial ryegrass and clover.  This pasture responds well to both grazing and mowing, and is thus the pasture of choice for most stonefruit and apple orchardists. While white clover is very shallow rooted and tends to 'burn out' in summer, perennial ryegrass is more persistant. In a dry year, even the ryegrass will die back, as it is not especially deep rooted. In addition, it can be badly affected by both grass grub and stem weevils. Ryegrass resists insect attack if it hosts a fungus in its tissues which produces a substance which dissuades insect feeding. The chemicals produced by these 'endophyte' fungi can cause a toxic reaction in grazing animals ('ryegrass staggers'). Ryegrass without this endophyte is strongly preferred by sheep. In summer, sheep will spend 5 times longer grazing clover (where it is available) than ryegrass (whether endophyte free or not). Their proportional preference has been established at 70% clover and 30% ryegrass, at least in summer. In the over-lush growing conditions of spring and autumn seasons more mature strawy grasses may be preferred. A good ryegrass and clover sward would hope to achieve clover levels of 30%. It is not easy to maintain a high clover concentration in the sward over time, although specialist summer clovers such as 'kura clover' are changing this. The downsides of a ryegrasss/white clover sward are the summer endophyte problem in ryegrass, and the loss of feed when clover dies right back in a hot summer. Summer clover loss also exposes the soil surface to even further drying out, and the open patches can be colonised by weeds when moisture returns.

Kikuyu
Increasingly common - and hard to get rid of if you don't want it - kikuyu has been introduced to the warm temperate zone from Africa to help step-through the lack of feed in summer (as was paspalum grass). Kikuyu is an irritation in the home orchard as it spreads by underground rhizomes and pops up where it is not wanted. In good conditions, it grows very fast, and its spreading and semi-rambling habit allows it to get into the lower braches of bushy trees, making eradication difficult ( a herbicide that affects grass species only is the best recourse - but can't be used on sensitive fruits, such as peaches and other stone fruit).

Kikuyu is a highly nutritious feed (70% or more digestibility) in good conditions and under good management, and it certainly does the job in summer, providing feed when there is little else. It also gives 100% soil surface cover in summer, helping to slow drying out. But it tends to supress clover when it is growing strongly, and worst of all, nearly disappears in winter frosts. A kikuyu sward without clover or other grasses that was green in late autumn can be almost totally brown in mid winter. Intensive and timely grazing and mowing in summer and autumn can allow clover to hold its own and be available for winter feed. As long as there are sufficient mouths to closely control the kikuyu in autumn, summer dormant/winter active subterranean clover might be the key legume for this pasture. Kikuyu swards winter productivity can be boosted by very close mowing in autumn (preferably almost 'scalping' it so some bare earth shows) and oversowing with winter-active annual ryegrass. Ideally, at least a third of the sward would be legumes and winter active grasses.

But even a pure stand of kikuyu has its uses - in the right situation. It can be a very useful summer 'lifesaver' if it is isolated to a secondary area, such as an open woodlot. 

'Mixed swards'
This is a euphemistic term for swards between rows of trees that have been sprayed out of kikuyu or other vegetation, then left for various grasses and herbaceous annuals and perennials to regenerate. Just what appears depends on the seeds dormant in the local soils, the species present in adjacent wastelands, and whether any attempt was made to sow clover and perennial rye, or any other grass legume mix. The ultimate composition is also influenced by whether or not the sward is allowed to reseed, as some of these 'wild' grasses are annuals. Swards that are cut or grazed fairly often, and that are always cut in late spring, tend to favor low growing grasses. Those cut or grazed infrequently, and never in late spring, can favor taller grasses.

Improving mixed swards
Simply applying fertiliser will change species composition and percentages - for the better. Fertiliser applied to low fertility areas favors the more fertiliser-responsive species initially present in low numbers to increase at the expense of less responsive annual grasses. Simply applying superphosphate and lime can double the percentage of clovers in the sward. Adequate fertiliser applications can shift species composition from low fertility annual species such as hair grass (Vulpia dertonensis) and shivery grass (Briza minor) to more responsive perennial species such as sweet vernal, soft brome, kentucky bluegrass (Poa pratensis) and perennial ryegrass (a few wild species such as Microlaena stipoides, a shade-adapted, drought hardy creeping perennial, are genuinely useful and fertiliser responsive). The greatest shift occurs with both increased fertiliser and careful grazing to allow light into the base of the sward. This encourages 'tillering' (budding of leafy - and therefore nutritious - side shoots from the base of the plant) in fertiliser responsive grasses. It also increases clover growth.
 
Even the simple intervention of a single application of 685 kgs of superphosphate per acre, followed by oversowing white clover has been shown to bring a very large jump in pasture yeild in the year after application, and the large improvement (sometimes pasture dry matter yeild can even double) persists for at least 6 years.
 
Highly productive ryegrass-clover based commercial pastures need to be re-sown every 7 or so years to keep ryegrass the dominant species. As sheep are a by-product of home orcharding, such strenuous efforts are not required. It may be better to concentrate on developing a legume and grass based sward that is permanent and able to provide reasonable grazing in most winters and most summers. Keeping the flock small enough to allow areas to be 'locked up' and left to re-seed naturally may be an important strategy for long term easy sustainability. Short-lived herbs, such as the biennial chicory, either have to be regularly oversown, or, less effectively, left to reseed naturally from ungrazed waste areas into adjacent grazing strips.

As home orchard soils are usually well fertilised, fertiliser responsive and winter active fescues, and perhaps cocksfoot, may be more strategically useful than ryegrass. In one trial, lambs fed exclusively tall fescue and clover pasture from birth to sale grew at a much faster rate than those fed the traditional ryegrass and clover. This reason isn't known - perhaps it reflects the deep rooting, summer productiveness of tall fescue, giving more, younger, leaves than ryegrass, with more metabolizable energy and better protein content. All of which results in the lambs obtaining higher quality per summer bite relative to ryegrass.

 The key elements to improving a mixed sward are:

• oversowing legumes and summer and winter active grass species into hard grazed pastures at the right time
• boosting base line phosphate and lime levels (and other limiting nutrients if necessary)
• careful grazing
  
• mowing less palatable species that are left ungrazed
  

In broad terms, the aim is to keep shifting the species composition until there is a good mix of species meeting several objectives. There needs to be a good proportion of deep-rooting and drought-resisting grasses and herbs able to access moisture from the lower layers of the soil, and thus supply food when the winter active grasses and more shallow rooted legumes dry up in a drought. There need to be humus-building species to enhance soil moisture retention and growth - deeply rooted species that break up soil pans, provide a channel to quickly move moisture deeper into the soil, and that provide large quantities of fine roots that build soil organic matter as they die and rot deep within the soil. There need to be a mix of grasses, legumes and herbs of such nature that tend to support sheep health by minimising the risk of bloat, provide high concentrations of protein year round to repair gut damage from worms, supply condensed tannins to aid worm resistance and resilience, and capture and concentrate some important microelements such as selenium. Of course, the cultivars selected should be highly productive through increased disease resistance and genetically increased growth potential.

Access to irrigation for fruit trees influences the sward management strategy
If the strategy as a home fruit grower of citrus (or other surface rooted fruit tree) is to encourage tall grasses such as tall fescue  and soft brome in order to get the greatest amount of mulch (and greatest amount of soil building fine roots), then the grass can be left uncut until it reaches full height near seed maturity in late spring/early summer. In the interim, the sprayed-out bare soil under the citrus will need to be irrigated. Once the grass is cut and pitch-forked onto the irrigated citrus, little re-growth is likely until late summer rains. Re-growth between the rows can be expected in earnest from autumn on, and as the main citrus season is winter, controlled sheep grazing at this time fits in nicely. The sheep would have to be kept out of the citrus/feijoa/casimiroa rows from spring onward to allow the tall grasses to grow to full height, but grass is usually abundant at this time anyway.

Under this regime, taller legumes are needed - lotus or perhaps sulla. Some of the taller ladino white clover cultivars might also be able to persist.

But, if no irrigation is available, it is very unwise to leave the citrus trees unmulched until summer. Most of the early seeding annual and perennial grasses, such as Briza minor (shivery grass, an annual, ~20 cm), Poa annua, and a little later, the perennial Anthoxanthum oderatum (sweet vernal) produce too little bulk to warrant leaving to mature. In the absence of irrigation, and on very free draining sandy or volcanic soils, other mulching material has to be found. In this case, the land between the rows might be planted in a drought resistant grass, such as tall fescue. This can be cut in mid spring before it is fully mature and while the soil is still moist. If the fescue has been well fertilised it should grow back strongly, and can then be grazed into early summer. If the summer is shaping up to be dry, the fescue can be kept to about 3 cms, reducing competition with the orchard trees.

Fitting sward choice to breeding sheep for lamb production for the home freezer
If you want to grow a few lambs, there are several critical times of year when there has to be plenty of nutritious feed available. Nutritious feed has a good protein content, which helps ewes ovulate, ample milk form, and lambs grow. Lambs in the womb do most of their growing in the winter months, so it is very important to have strong winter growing grass species - unless you have bought in good quality hay or (expensive) supplements.

Broadly, pasture is most nutritious in the lush leafy developing seed head stage prior to seed head maturity and 'strawing' of the stem. Overall, most grass species when young and immature are quoted by authorities as having a 'dry matter' content (i.e. non-water) of around 20%- 23%, which, they say, after taking into account the relatively indigestible parts, for nearly all common grass species typically yeilds 11 megajoules of metabolisable energy for every kilogram of dry matter consumed. Thus, from an energy standpoint, the species of grass you choose will be pretty much on a par with any other when grass is abundant and starting to seed in spring and early summer.

Given values of 11 mJ  per kilogram of dry matter, it is easy to calculate that a kilo of fresh cut young grass must have - very approximately - 2-3 mJ of metabolisable energy. A ewe is said to need about 8 to 10 mejajoules of metabolisable energy a day to maintain weight (larger animals need more, smaller animals need less). This translates to a daily requirement, depending on grass quality and ewe size, of from about 2.5kg to 5kgs of fresh grass per ewe per day to maintain bodyweight.

While the daily energy needs of the breeding ewe to maintain bodyweight is relatively low over summer, extra energy is needed in late summer/autumn to lay in fat for good ovulation. About 1.8 kgs of dry matter a day per 60kg breeding ewe is quoted by experts as needed to 'flush' the ewes in the period immediately before mating. As lush immature grass has, conservatively, 20% dry matter content, 7.2 kgs of fresh green sward a day would be needed by each ewe at this time. This seems absurdly high, as some trials show 56 kg dry ewes ad lib feeding on ryegrass and/or clover pasture of their choice ate only 1.36 kg fresh pasture a day. This quantity took about 5 hours to consume. On this basis, the ewes would need to feed 24 hours a day (at their observed intake rate of 5 grams a minute) to be able to force down 7.2 kgs of fresh pasture! This real-life observation also throws into doubt the calculation that, 'theoretically', a ewe needs to eat 2.5kg to 5kgs of fresh grass per ewe per day to maintain bodyweight. From the data mentioned above, even in conditions of ample feed supply in front of them, they would need to graze for about 10 hours per day.

On the basis of the 'real life' observations, realistically, maintenance is more likely to be about 1.kg to 1.5kg of fresh high quality pasture per day, depending on ewe size. Obviously, poorer quality pasture will require a higher feed intake.

While interesting, these theoretical considerations have little practical meaning for the home fruit orchardist. Sward height and 'lushness' is the only meaningful measure, and can be quickly assessed by eye.

The best rule of thumb is that you can feed from any pasture height down to a residual height above soil level (ignoring uneaten high grass around dung deposits) of about 3 cms for short grass pastures based on kikuyu, Poa annua and ryegrass. You can graze down to about 5 cms in tall fescue, phalaris, and prairie grass dominant tall grass swards (so long as fertility is good). The taller the grass to start with, the longer time before the sheep reach the minimum residual height of uncontaminated pasture. The sheep must be shifted when the uncontaminated part of the sward in the enclosure has been eaten down to the minimum advisable residual height. It could, of course, be further eaten down, but this compromises grass vitality for re-growth. At the point where even dung patches have been eaten close and overall only about 2cm sward height remains, they do not have enough to eat, and will start to get thin. In times of shortage, grasses sometimes have to be grazed harder than is strictly good for them. For short grass swards, the sheep can be kept moving onto swards of around 3 cms height and off again at 2 cms, which will usually maintain their weight, but usually will not allow the ewes to lay on storage fat. At this level, they would eat more if they had more to eat. Grazing long grass swards, such as tall fescue or cocksfoot, down to this level would be most undesirable, as recovery woud take a long time, and some plants may not recover at all.

For flushing the ewes in autumn, the pasture needs to be high quality and abundant enough to sustain the removal of at least double the 'weight maintainance only' level (i.e.the pasture needs to be at least 5 cms high for short grasses, and at least 7 cms high for tall grasses). Quality can be boosted with specialist feeds. Additional high protein feed from certain legumes (for example, sulla and birdsfoot trefoil) grazed in the ten days immediately before mating has a different physiological pathway to feeding more metabolisable energy in good grass, or metabolising the proteins in clover in the rumen. The result, however, is similar to flushing on grass. Feeding these legumes boosts ovulation and retention of embryos, and thus results in more lambs (an increase of about 5-10%). However, birdsfoot trefoil is not really persistant in a sward, and sulla is a fairly large plant. Both might have to be grown seperately.

A little better than maintainance is all that is required in earlier stages of pregnancy. But in the last month of pregnancy a similar amount of feed to flushing (about 2 kg to 3 kg of fresh high quality pasture per day) is needed to build large healthy lambs that will survive. Again, smaller ewes have lower requirements than this. Where mating is controlled, it can be timed (gestation is about 5 months in sheep) so that birthing coincides with the first month of spring, when the sward is not only starting to grow more vigorously, but has the highest quality. Where mating isn't controlled, lambs may be born in late winter and the ewes will need plenty of high quality of feed - at time of very slow pasture growth, although the growth rate is starting on a slowly rising plane. 'Plenty of feed' can be defined as being presented with a sward height of 4 cms, which is generally regarded as indicating 1,200 kgs of dry matter per hectare. Studies have shown that a pasture of this height allows maximum intake by the ewe, and maximum weight gain. But it also means moving the sheep before the sward height drops to 2 cms, because at this height, there is not enough feed, and additional energy is used in grazing extremely short grass. At 2 cms sward height the ewes will have to draw on fat reserves for part of their daily energy needs. The ewes start to lose weight, and the lamb in utero is not adequately provided with nutrients.

The first six weeks after lambing make heavy demands on the lactating ewe (sheeps milk is very rich - 30% fat, and high protein). She needs a sward that can provide the greatest possible amount of high quality feed. Nutritional requirements for a 60 kg ewe feeding a lamb are supposedly 2.6 kgs of dry pasture matter (13 kgs fresh sward per ewe on theoretical calculations) per day, and more for a larger ewe feeding twins. But more realistically, the requirement might be 4 to 6 kgs of the highest quality lush sward per ewe per day (less for a smaller ewe, more for a larger ewe with twins). This peak daily feed requirement in the yearly cycle should fall in early and mid spring. This means the sward has to hit its peak growth rate at this time. Ryegrass has been the grass of choice to fit this profile in shorter grass swards, and tall fescue and cocksfoot does the job for long grass swards.

As a very rough estimate, the ewes and lambs should be presented with a sward at least 4 cms high, and shifted to similar height pasture when it is eaten down. (There is no additional weight gain on even higher sward.)  This means that the sward should be managed to include strongly growing grasses such as ryegrass and some tall fescue varieties that are both productive and also peak their production in early to mid spring. It is also essential that the sward is 'high quality' - each mouthful should contain as much energy and protein as possible, and contain no anti-nutritional factors.

Fresh immature grass species typically have about 3% metabolisable protein per fresh kilogram (12% crude protein per kg dry matter). This is broadly the same protein content as 'nutritious' grains such as oats and wheat - and higher than maize seed. Only phalaris has a significantly higher protein content than other grasses at the immature seed head stage.

Legumes - and particularly white clover - have a higher crude protein content than actively growing immature grasses. The crude protein is typically around 15% per kilogram of dry matter. A mature clover plant has about the same dry matter content as lush immature grass (23%), so a kilogram of fresh clover contain very roughly 4% crude protein. Higher protein legumes are broken down more rapidly in the rumen compared to grass. These high proportions of protein in the rumen content (relative to carbohydrates and to less digestable fibrous/lignin-containing forage) means that the nitrogen content is not used as efficiently as it would be if better balanced with fibre or carbohydrate-containing forage. As a result, the dung and urine contain more nitrogen than would otherwise be the case.

Paradoxically, soluble proteins, whether from lush grasses or legumes, can form a foaming mat in the sheeps rumen, preventing gas escape, and inhibiting feeding until it is belched out (a condition known as 'bloat'). Plants with condensed tannins - lotus, sulla, dock - bind and precipitate the soluble proteins and by-pass them out of the rumen to the intestine for digestion, improving the overall efficiency of use of the protein content in these legumes. These plants do help reduce bloat where they are present in sufficient quantity (1- 3% by weight), but a major factor increasing the risk of bloat is introducing hungry animals to lush pasture, when they gorge on large amounts of highly fermentable greens. The 'protein fermenting' enzymes within the plant cells are released when the leaves are chewed and placed in the ideal fermentation conditions of the rumen. The proteolytic enzymes coupled with microbial action can result in fast release of both gases and bio-foams, with potentially disastrous results.

If winter-active pasture species are selected and matched to the correct stocking rate, the sheep will always have good quality grass available, they will not need to gorge, and the increasing tempo of grass growth in spring will match the increasing appetite of ewes in late pregnancy and in early lactation. Where feed is unexpectedly short and animals have to be turned out on lush winter saved 'feedbank' areas, it would be ideal if the stored green feed sward included a good percentage of lotus.

Modern pasture species have been bred to maximise protein content. As a result, plants have tended to have relatively low amounts of energy-providing soluble carbohydrates ('fructans', fructose polymers, are the main carbohdrate storage form in grasses) relative to their protein content. Imbalance between the soluble carbohydrate content of the plant and the protein content has meant that the protein is not fully metabolised. When grass and clover is lush in spring and autumn (and wet summers), there may be more protein than the microbial flora can use. The excess ends up as unused ammonia, which is absorbed into the bloodstream from the rumen. Ultimately, it is excreted in the urine. In the worst case, (mainly involving dairy animals and under unusual conditions), up to 40% of the nitrogen in the sward eaten is lost as methane and as ammonia.

Some pasture cultivars have been bred with increased levels of soluble carbohydrate, which increases the efficiency of the use of the dietary nitrogen ingested. In addition, they compensate (in part) for decreasing protein content as the grasses mature and decrease in protein while increasing in lignin content. 'High sugar' winter active lolium and festucalolium cultivars may be a worthwhile investment for better quality late spring/early summer feed for lambs. The caveat is that excessive carbohydrate (especially where sheep pellets are also being fed) in the sward may be implicated in one form of lameness, laminitis, a painful swelling of part of the hoof.  Lolium and Festuca arundinacea both have some of the highest levels of water souble carbohydrates, particularly in spring.

Some roughage, whether hay or coarser grasses, may be useful to 'balance out' the percentage of protein, soluble carbohydrate, and relatively poorly fermentable 'coarse' lignaceous and cellulose material that might help rumen health. This may be particularly important in spring and autmn when rapidly growing ryegrass is dominant. But structural carbohydrates, such as the lignins that give grasses leaf rigidity, have been reduced in some cultivars.

Paradoxically, it is possible that coarser-leafed grass cultivars with good fructan and protein contents might provide the best balanced solution for achieving both maximum lamb growth and minimal health problems due to lush feed and excessive protein and/or carbohydrate. (Keeping hay available at all times might achieve the same result).

All the legumes - white clover, red clover, and lucerne - are noted as excellent growth foods at all stages of plant maturity. In this respect, they are at least as valuble as grasses, as, in complete contrast to grass, their protein content doesn't change markedly with life-stage. But in winter, clovers grow very slowly.

The problem is mirrored in summer. The need is to keep clovers active long enough into the summer to mature the lambs to a larger size, if that's what you want (a typical weaner lamb killing out at around 12 kg carcase weight at 4 months may put on several more kilos over the next few months, or grow reltively little, depending mainly on on its health and the quality of feed available). Of these legumes, white clover is probably the most valuable in low-care large orchards. It will grow all year round except for dry summers; and there are now more dry tolerant cultivars becoming available anyway. Hopefully, by the time it stops growth due to dry, even late born lambs will be big enough to sell or kill. If you could be bothered, you could grow separate strips of pure white clover to 'pump up' lamb growth in spring and early summer (lamb growth is even faster if some ryegrass is also - separately - available). The downside is that the clover will all but disappear in the midsummer heat. Red clover is more seasonal, but if managed correctly, can provide good summer feed. Caucasian clover also has a reputation for summer persistance, but it has not been used much, as it requires extra care for several years to get established.

A few breeds - mainly merino, dorset, and some northern european short tailed breeds - can mate in late spring and lamb in autumn if the ram is kept with the flock. This partly fits in with sward productivity - flushing is in mid/late spring when feed is plentiful and lambs nearly weaned, and late pregnancy overlaps with late autumns plentiful feed. The sward really needs a late autumn 'bagged nitrogen' dressing to keep it growing as long as possible into early winter when the lamb is born. The lambs are born when there is least amount of pasture available to support heavily lactating mother sheep. Therefore, winter active pasture grasses such as fescue and perennial ryegrass are essential for this strategy; as is ample reserve pasture. Winter lambing has the greatest mismatch to seasonal sward growth, and should be done conservatively, or not done at all.

Increasing pasture growth
The objective is to match the changing needs of an appropriate number of sheep throughout their lifecycle with the amount and seasonal growth pattern of the particular species in your sward. The trick is not to overgraze the sward to the extent root growth and therefore drought resistance and fertiliser responsiveness is compromised, but to sustainably 'push' the grass and legumes to produce the largest amount of nutritious plant parts at the most critical times for the sheeps needs. Some factors affecting grass growth (mainly the weather) can't be controlled, and some can. The availability of key plant gowth nutrients is one of the most important factor under the orchardists control. Limited plant-available nitrogen is an almost constantly present factor - regardless of the time of year - that stops the expression of the full growth potential of the grasses of the sward.

Thus nitrogen is the key element for plant growth. Whether from a bag, from urine, or from decomposition of organic matter, it is the same element. The commonest plant-available form of nitrogen is nitrate. This is produced as a regular part of the cycle of decomposition in the soil, but the amount is severely constrained by the soil temperature, availability and spatial distribution of organic material, and seasonal cycle of biological activity.

In contrast, bagged chemical forms of nitrogen (such as urea) are available independant of the seasonal peaks of soil organism activity, can be spread evenly, and make nitrate available to plants roots within about 2 weeks of application. Under very good growing conditions, there can be a response of 25% or better in pasture dry matter within 3 weeks of application of moderately high rates. The response is visible after about 10 days of application. In good growing conditions, the extra growth response continues for about 6 weeks, then tails off rapidly.

But if conditions for plant growth are good, clovers and other legumes should be 'doing the job' of supplying nitrogen. Bagged nitrogens greatest value may be in winter, in times of poor growing conditions for clover; conditions which also give relatively poor sward response to nitrogen from any source. But in winter, even a limited growth response is worth having.

Winter growth response depends on there being an actual deficiency of nitrogen - some winters are warmer and drier than others, and there may be good winter growth without additional nitrogen. Other elements, such as potassium, must not be markedly deficient, and the pasture species must be those that grow well in winter (ryegrass, prairie grass, Poa annua, Kentucky blue grass, cocksfoot, tall fescue, Yorkshire fog).

Bagged nitrogen fertiliser
The pace and timing of biological processes that contribute nitrogen to the sward are often mismatched with the needs of pregnant ewes and rapidly growing lambs. This is the most important reason for using bagged nitrogen. And when there are no legumes present to fix atmospheric nitrogen into the soil, there is little practical alternative to using bagged fertilisers on swards (recognising that well decomposed compost can be used under orchard trees - except that the greatest amount of nitrogen will not be released until biological activity accelerates rapidly in spring).

nitrogenous fertilisers
Urea, a salt derived from ammonia gas and carbon dioxide, is easy to handle (it is granulated and coated with inert material to prevent absorption of atmospheric moisture and ensure free flow), is one of the most concentrated forms of nitrogen (at about 46% elemental nitrogen), relatively cheap, and is in a useful form - in that its conversion to soluble nitrate takes place over one or two weeks thus lessening the risk of loss from leaching into the groundwater. Urea does, however, temporarily form ammonium carbonate under the influence of an enzyme in the soil. This creates a short-lived alkaline condition, which converts some of the ammonium to to ammonia gas which in turn volitises off into the atmosphere under warm, windy, and dry conditions. In cool soil conditions the enzyme works too slowly to create markedly alkaline conditions, and little nitrogen is lost.

Sodium and ammonium nitrate provide 'instantly soluble' and thus 'instantly available' nitrates, but unless they are used immediately by the plant, they are suceptible to being quickly leached out of the soil by rain. They are not affected by volitisation in warm conditions. Its advantage is that it is not dependant on nitrification processes by soil bacteria to create the soluble nitrate ions, and so provides unconstrained instantly available nitrates in winter when soils are cold and bacterial and enzyme activity is very slow. If ammonium nitrate is mixed with basic fertilisers such as lime or rock phosphate, it will tend to lose some of its nitrogen content in storage.

Sulphate of ammonia is about 21% nitrogen and 24% sulfur. It is not affected by volitisation. The highly soluble ammonium ions tend to displace calcium ions (and other basic ions) in the soil. Calcium sulphate is formed, which is more soluble than the soil calcium carbonate (lime) from which it was (in part) derived.The calcium sulphate washes out, tending to leave the soil more acidic than it was previously. Sulphate of ammonias acidifying effect can be neutralised by applying about the same weight of lime some weeks later. It is slightly more expensive than urea.

Amount to use
The question is how much nitrogen to use. Application rates under about 20 kgs/N/hectare (2 grams per square metre, e.g. 4 grams - about a teaspoon - of urea form of nitrogen) produces relatively little response. From about 50 kg/N/hectare (5 grams per square metre, e.g. about 10 grams of urea, roughly a level spoonful ) onward there is the potential to gain approximately 25 kgs of dry matter for every additonal kilogram of nitrogen applied, until high rates are reached (250 to 400 kg/N/hectare, depending on presence or absence of other limiting factors), when the response to each additional kilogram of nitrogen becomes less and less.

There is no doubt that where soils are moist and have responsive pasture species, there can be spectacular increases in the amount of grass when very high applications are used (say 400 kgs nitrogen per hectare in seperate smaller dressings throughout the year). Better than 75% increased growth on soils with high phosphate levels have been achieved. But at these rates, there is also four times higher nitrate leaching, and some research claims supression of clover above 200 kgs/nitrogen/hectare/per year. 200 kgs nitrogen/hectare is equivalent to roughly 4 tablespoons urea per square metre (a moderate sized handful) per square metre. This is a lot of fertiliser. It is not necessary - or desirable - to go to these extremes to get some strategic extra grass growth.

In addition, for more shallow rooted swards, such as ryegrass/clover, nitrates are only taken up in the top 45 cm of soil. Heavy applications of urea on a damp soil can move nitrates 150mm down with 50mm of rain. Thus, any nitrates not taken up by plants in the top 45 cms is likely to be moved out of reach after persistant or heavy rain - especially in free draining soils. Nitrate leaching through the soil is negatively charged, and tends to take positively charged basic minerals (calcium, magnesium, potassium or sodium) with it, accelerating natural acidification and reducing the base exchange capacity of the soil.

Finally, there is some indication that heavily nitrogen fertilised grasses that have taken up addition nitrates have more rumen degradable protein than the balanced rumen can handle. This 'undegradable' protein is simply excreted in urine, with little, if any, additional gain in animal growth.

The most efficient pasture growth increases are achieved at application rates of  20-40 kgs/N/hectare. Higher rates give a smaller increase in pasture growth per kg of nitrogen deployed. The total number of applications in a year should be tailored by strategic consideration of the actual situation in each distinctively different area of the orchard sward.

Excessive amounts of nitrate
Stock can handle some nitrate in plant tissues (About 0.1 of a gram of nitrate in feed per kilogram of bodyweight is generally recognised as probably safe - a 65 kg ewe could safely consume about 6.5 grams of nitrate), but high levels due to high application of urea can cause nitrate poisoning in stock. Lush feed, especially stemmy grass and herbs that are growing quickly (especially annual ryegrass and tall fescue), can build up high nitrate levels in their tissues. Usually, absorbed nitrate is quickly turned to protein. But excessive nitrate applications, especially in conjunction with environmental conditions that lead to nitrate accumulation - cloudy days with low light, or dry droughty conditions followed by rain  - can result in an increase in the amount of nitrate in stems and leaves.

Nitrate is first converted to nitrite in the rumen and then to ammonia which is used by rumen organisms. Nitrate conversion to nitrite happens faster than conversion of nitrite to ammonia. When too much nitrate is present in the pasture consumed, nitrite builds up, some is absorbed into the bloodstream where it reacts with haemoglobin to convert it into methomoglobin, which cannot carry oxygen. The tissues become starved of oxygen. Symptoms are dose dependant. About 0.3 of a gram of nitrate in feed per kilogram of bodyweight is considered hazardous. Up to a third of haemoglobin converted produces only slight symptoms. It may be scouring, poor appetite, and drowsiness. Iodine uptake is impaired, and thus thyroid function is impaired. Sub-acute amounts cause tremors, unsteady gait, or, with greater conversion of haemoglobin, collapse and shallow and rapid panting. Pasture containing about 6 grams or more of nitrate in feed per kilogram of bodyweight will cause acute poisoning. Situations resulting in acute poisoning from pasture are very rare. When 70% of the haemoglobin has been converted convulsions, coma, and then death is certain. Fortunately, sheep are less suceptible than other livestock, and the danger is less if the sheep are introduced to higher nitrate pastures gradually so the rumen microorganisms can adjust to the higher levels. On-going, chronic nitrate poisoning is rare; occasional low level nitrate poisoning is more likely.

Introduce sheep to lush pasture gradually, especially if it is largely ryegrass or tall fescue (the species most likely to accumulate nitrates - ryegrass and fescue with 'wild' endophytes may have a slight protective effect due to the vasoconstricting endophyte phytochemicals slightly offsetting the vasodilating effect of nitrate). Be particularly cautious if there have been periods of overcast or dry weather immediately prior to grazing. Allow time for the rumen to adapt to the higher nitrate levels. Do not put weak or unhealthy animals on pasture suspected to be likely to have unusually high nitrate levels. Pre-feed with hay (not ryegrass or fescue hay) or carbohydrate rich sheep nuts to limit initial intake.

Timing of applications
Pasture growth can be 'boosted' in early spring by applying some urea nitrogen (about 80 kgs urea per hectare, containing roughly 40 kg N). But this must be done carefully and sparingly. Better, don't let some strips become lush while leaving animals too long in other areas.

Worse, heavy applications can cause soils to become increasingly acid, and damage the vital rhizobia nodules on the roots of white clover that 'naturally' fix atmospheric nitrogen into the soil. White clover is not known as 'white gold' for nothing. It's act of 'pulling' nitrogen from the atmosphere into the soil means cost free fertiliser as long as it has what it needs to grow.

But urea applied before winter can both help to create high quality leafy feed to flush ewes in autumn and also capitalise on warmer winters by providing a residual boost to winter growth at a time when ewes have high nutritional needs. The greatest response comes from sward that hasn't been grazed too hard, or damaged by late summer drought. Younger swards, particulalry, respond to strategic nitrogen (typical rates are moderate, 20-30 kg/nitrogen/hectare) with increased numbers of tillers, and better tiller survival under grazing.

Autumn urea applications (typically at lower rates, e.g. 20 kg/N/hectare) to compensate for poor nitrogen fixation by white clover is one of the most useful strategies to maximise feed in winter when sward growth is severely 'pinched'. While clover will use applied nitrogen for its own growth in preference to 'fixing its own', nitrogen fixation is low in cool season temperatures anyway, so the forgone 'free nitrogen' from clover is a tiny cost relative to the large benefit to the grass.

Lime and timing urea applications
When temperatures are high (around 83^o F) urea volatises off much more rapidly in the prescence of lime. (Alkaline materials cause ammonium salts to give off ammonia gas.) For this reason, most fertiliser companies recommend a gap of around 2 months before applying urea to a newly limed paddock. Conversly, urea is 'fixed' in the soil within about a week, so liming can be safely done about a week after an application of urea, with no danger of altering the response to the nitrogen fertiliser.

Clover biological nitrogen fertiliser
Specialised bacteria living in 'nodules' in clover roots capture atmospheric nitrogen, which is used to build their own protein, and part made available to the host clover plant as ammonia in return for sugars manufactured by clover as a result of photosynthesis. This atmospheric nitrogen incorporated into the totality of the clover tissue in the sward is made available to the soil partly (about 25%) from decay of clover roots and stems underground (continual die off and new root growth means that virtually the entire root mass will have replaced itself over autumn), partly from the nitrogen rich clover leaf litter (clover leaves contain about 5% nitrogen), and partly (20%) from the urine and faeces created from sheep or other herbivores grazing the clover. Some nitrogen is lost from dung and urine, some is incorporated in animals bodies, whether insect, mollusc, or herbivore. Somewhere around 70-90% of the nitrogen content of that part of the clover biomass in the sward that is eaten by herbivores is initially deposited either on or in the soil in herbivore excretions. Much of this recycled clover nitrogen is subsequently captured by grasses to support grass growth; grasses, in particular, are much more efficient than legumes at taking up free nitrogen compounds that become available in the soil from decay or excreta.

Because the nitrogen from clover has to go via the decay process - or via faeces and urine - most mineralised nitrogen is used by grasses and herbs immediately it becomes available in the soil, whether directly in urea, or indirectly via soil organism decay. Nitrogen is also used in the growth in the constantly changing populations of the soil biota. As a result, most of the nitrogen in the soil is largely in organic form, and only around 1-3% of the total organic nitrogen is mineralised in the soil per year (one study 'model' claims 5-9%). As the rate of mineralisation is low, and the rate of uptake by plants is very high, very little of the clover-derived nitrogen is lost to leaching.

Clover, a legume and thus largely independant of soil nitrogen, is particularly nutritious, and preferred by sheep when sward quality is sub-optimal. Clover in sheep swards usually ends up with small leaves and short internodes due to the constant grazing pressure. Probably the main factor limiting clover growth is lack of soil phosphate. As long as phosphate levels are adequate and the soil is not too acid, white clover should grow well in moist soils. It is subject to a number of pests and diseases (root nematodes, root and leaf eating weevils, slugs, viruses, etc), but if your clover is badly affected, it is probably not worth doing much about it.

But letting grasses grow too tall will shade out most cultivars of clover. If grass gets ahead of your stock in spring and autumn, it pays to mow it if you can. The amount of mulch obtained is probably more nuisance value than use, but if you want to increase pasture growth naturally, you'll have to top rankly growing grass before it supresses the clover, especially if you don't have some hungry lambs and lactating ewes to soak up the excess.

The highest recorded amounts of nitrogen fixed by red clover and by subterranean clover are roughly 200kg of nitrogen a hectare. The record for white clover is about double that. Only pure stands of lucerne can match it. More typically, white clover contributes anything from 100 kg to 350 kg of nitrogen per hectare per year, depending on temperature, amount of clover in the sward, effectiveness of the strain of rhizobium infecting the clover roots, vigor of the plants, soil moisture over summer, and soil fertility. The percentage of clover in the sward, and summer soil moisture availability are the major influences. In one trial, low (around 8%) amounts of clover has been measured as contributing only around 24kg to 48kg nitrogen/hectare/year - and this may be fairly representative. The greatest contribution of clover-nitrogen comes at around 35% clover content in the sward.

White clover contributes relatively little nitrogen in winter as it grows very slowly at temperatures below 10^oC, and provides very little extra nitrogen to the grass and herb component of the sward. At this time, a large part of the clover photosynthetic product goes to support the roots. The roots nitrogen fixing activity more or less matches the temperature-driven low requirement for leaf growth at this time of year. Thus, when temperatures are low, adding nitrogen makes no difference to clover growth. And as nitrogen fixation is much lower than later in the year when it is warmer,white clover produces relatively little excess nitrogen to boost grass growth in winter. In contrast, ryegrass leaves will expand and grow relatively well in winter provided it is not limited by lack of nitrogen. Fortunately, trials have shown that autumn and early winter applications of low rates of nitrogen (45kgsN/hectare) does not suppress clover growth in the subsequent spring, but does boost winter grass growth.

Until winter-active clover ecotypes are selected (possibly from northern Eurasian white clover populations), urea or other nitrogenous fertilisers will have to take white clovers place in winter. Winter active annual clovers, such as subterranean clover or balansa clover, could be used; but their persistance in the sward is dependant on successful annual seeding.

Animal biological nitrogen
Urine contributes useful amounts of nitrogen to the soil, albeit highly localised. Between 60-90% of the nitrogen in the portion of sward-grasses, legumes, and herbs consumed by cattle is initially returned to the soil in their urine. Presumably the calculation for sheep is similar.

In any event, the aim is not to graze the sward too heavily, or the roots are weakened and the plants lose drought resistance. On the other hand, the pasture can't be allowed to get so lanky that it shades out the more prostrate but light dependant clovers. Clovers and other legumes are the engine room of the sward. Ideally, sheep will be stocked heavily enough that they are forced to eat the less palatable species as well. This prevents the most palatable species being hammered, having only root reserves of carbohydrate to draw on in order to grow new leaves (the fructan reserves stored in leaf sheaths and shoots having been removed by the sheep), and growing weaker and weaker. In the meantime, the worst species are left alone to grow on and ultimately dominate the sward. A heavily grazed preferred species puts up tender new growth as it re-grows. As sheep prefer new regrowth foliage, this is selected again and again, becoming weaker and weaker unless it is allowed to recover. It will not be able to re-grow until the sheep are finally shifted out. This means that ideally the orchard should be able to be grazed section by section, and that the sections are small enough (or the flock large enough) that the area is grazed out within 5 days or so. If the sheep numbers are so small, or the area so large that the sheep remain in the same place for weeks at a time, the most palatable species simply can't recover.

The objective is to have the 'right' number of animals for 'right' number of enclosures of the 'right' size and the amount of seasonal growth of the 'right' nutritional value.

But no two seasons are alike, and the sward is often in slow shift of composition. A constant close match between animal numbers and optimal grazing height is therefore unlikely, no matter what the 'ideal' advice is. Usually there will be too much or too little sward, and the sheep will typically graze some species too heavily (down to the growing point close to the ground) while leaving others standing lush and tall. Mowing, supplementary feeding, and the selling and buying in of lambs are additional techniques to cope with the inevitable mismatches in the pastoral system. The aim is to match animal numbers and seasonal pasture growth as closely as possible as much of the time as possible.

Unfortunately, predicting how long a given area of sward will 'last' in summer and winter is more art than science. Using a carefully calibrated device, a 'falling plate', is useful in intensive commercial dairy production where the lush-grass/tall-clover 'duoculture' is homogenous, long, and often sprawling as much as upright - but it is of little use in the upright, often tightly clipped sheep swards of 5 cms and less. While measuring standing sward height with a simple ruler (from 2.5 cm above the soil surface to averaged grass/legume/herb leaf tip height) can give an idea of how much dry matter is available at any one time, such estimates are often biased by the patchy nature of sward height, highly variable and patchy species composition (in the home orchard, at least), the denseness or thiness of the sward, growth differentials in wet or in dry areas, and by the number of measures taken to get the average height. Knowing how many sheep you have, and whether they need 'plenty' of feed for growth (lambs), 'plenty' of feed for ovulation (ewes), or just 'maintainance amounts' (rams outside the breeding season), you could estimate their 'ideal' daily feed levels, calculate the area of a given enclosure, measure average sward height, thus estimate the dry matter present, and from that estimate how long the enclosure will 'last'. This is a waste of time in most cases.

Usually, available uncontaminated pasture availability can be judged by walking through the enclosure, noting how badly hammered the preferred species are, and whether less preferred species have been touched yet, and overall how much growth (uncontaminated by droppings) is present. The mental assessment is then made, "enough feed for another week/few days", or "they will need shifting tomorrow". This is the crunch point. Has the sward in the next enclosure in the rotation regrown sufficiently? It has to have grown enough that the sheep can be left there for whatever length of time is needed (while still feeding them appropriately well throughout their stay) to allow the sward in the next enclosure again in the rotation sequence to also finish growing sufficient feed.

Given a basic level of fertility, the season is the prime determinant of how quickly the sward will regrow. Experience of how quickly sheep graze off the sward in winter soon teaches the home orchard grower the stocking rate limits of the current area of sward. It also teaches how often the sheep have to be shifted for the current size and number of enclosures. (Individual enclosures may have their own limitations - an orchard area may be quickly pugged by the sheep in winter, but support better than average summer growth.)When grass is lush in spring and autumn, the limit to the number of stock is determined more by how badly contaminated the sward has become (sheep are reluctant to eat near their own faeces) in the restricted space of the orchard interrows, and how long to allow sheep to 'hammer' the preferred species in the sward.

No amount of experience can help when there is a 'one in fifty years' drought or cold period. All estimates based on past experience are then of little use. Adjusting sheep numbers to low levels 'just in case' of a climatically extreme event means the pasture will almost always be out of control unless a mower is used regulalry, which somewhat negates the point of using sheep to control orchard sward growth.

Early Autumn
If summer has been dry and feed short, the rains of early autumn bring a flush of sward growth and the first chance to feed up ewes and the breeding ram to ensure good conception. However, rainfall can still be erratic and inadequate. Drought tolerant species may once more prove their worth. Kikuyu may still be growing very well even with limited rain, especially if nitrogen has been applied and the weather is still hot. Kikuyu should be kept to 'lush lawn height' - about 2 cm high - to encourage white clover in preparation for kikuyu's winter slow down and possible die back.

Autumn is the major seed sowing time. If summer brought severe drought, much of the white clover may have been wiped out. Time to consider whether to replace it with more drought tolerant species like caucasian clover, or go for more drought tolerant white clover cultivars. Time also to consider if you might be better off moving toward deep rooted more drought tolerant grasses; and if so, which species and cultivars. Paspalum levels can be assessed now - paspalum may be green in summer, but it is dormant and unproductive in winter. Better to spray out areas with a lot of paspalum and upgrade to summer and winter active grasses. Autumn is the major time of the year to do something practical to improve the productivity of the sward in the 'pinch' times of winter and summer. 

Autumn may be the major seed sowing time, but beware of unseasonal 'drys' early in autumn. Sow only when the soil is thoroughly moist and rain expected. White clover establishes best when there is still good warmth as well as rain, making early autumn a good time to sow this legume. If conditions are right, it may be possible to heavily graze some existing pasture and oversow with white clover, as it needs only shallow sowing.

Consider if you should sow legume and grass cultivars with improved winter activity, or summer drought resistance - or some of both. Some grasses, such as tall fescue, are slow to establish. Early autumn is warm and moist enough to give the seedlings the best chance, whereas later in autumn may be too cool for the seedlings to establish well. Ryegrass will also germinate well at this time, but it is so vigorous at the seedling stage it will outcompete slower grasses. For this reason it is perhaps best not to sow ryegrass in a mix with slower establishing, less vigorous grasses.

Autumn weeds such as thistles become more apparent, especially where there are bare patches in the sward. The safest approach is to grub out the offenders, or use non-hormonal herbicides such as glyphosate - being very careful to avoid drift onto orchard trees. There are hormonal herbicides that selectively kill broadleaf weeds with minimal effect on well established clover (and no effect on grass), but any unseen fine drift can be very damaging to orchard plants, especially young plants and sensitive species. You really do need to know what you are doing; do everything absolutely correctly, and act conservatively if you are to use them in an orchard situation. There is absolutely no room for ignorance, inappropriate spray gear, error, carelessness, risk-taking, or laziness.

If you are determined to use a hormonal compound against broadleaved weeds in orchard pasture, there is a wide choice of active material. Hormonal formulations include 2,4-D formulations (e.g. 'Pasture clean', 'Baton' 'Relay'), MCPA formulations (e.g. 'Clean Sweep', 'Crop Care MCPA') MCPB formulations (e.g. 'Soft Touch'), MCPA/B mixtures (e.g. 'Select', 'Tropotox Plus'), formulations of Dicamba (e.g. 'Banvel 200', 'Kamba 500'), Mecoprop/Dichlorprop MCPA mixtures (e.g. 'Duplosan Super') or Clopyralid formulations (e.g. 'Versatill'). To repeat, you must be ultra careful to avoid drift onto your own or anyone elses trees. Chemicals used to kill woody weeds are even stronger, and may be lethal to your trees when used incorrectly or inappropriately.

Chainsawing and then painting the stumps of woody weeds with these 'brush killer' type hormonal formulations is both perfectly safe and very effective. But spraying a 'scrub' or 'brush killer' preparation anywhere near woody orchard plants such as vines (unless they are dormant, and they are the only woody plants in your home orchard), tamarillos, kiwifruit and the like, or near herbaceous fruit such as mountain papaya is dicing with the distortion and/or death of your plants.

Apply a monthly dressing of a balanced NPK composite mix with trace elements (zinc and boron are particulalry important) to subtropicals, particularly trees that have an autumn growth flush (eg avocadoes).

This will also boost grass growth and help put condition back on ewes so they ovulate well for autumn mating. Ideally they will gain weight for a couple of weeks prior to and after mating ('flushing' the ewes to boost ovulation and embryo retention). If ewes are gaining weight (over 150 grams a day) over the mating period, there is good embryo retention. If the sward is very lush due to high fertility and warm rains, ewes can gain as much as 300 grams a day at this time - but this can  reduce implantation and retention of the embryo, due to a hormonal effect.

The other aim is to have ample feed in front of ewes in winter (commercially, farmers aim for around 1,400 kilogrammes of dry matter per hectare near lambing time. Pastures can be short but leafy and still have high amounts of dry matter going into spring. Paddocks that are short, but not very leafy are not producing enough to keep the ewe sufficiently fed to not have to draw on body reserves when lactating).

If autumn has not been good, and you are a little overstocked, you are worried about insufficient grass for winter, an additional dressing of urea can be used on the inter-row pasture to boost growth - if you have winter responsive pasture grasses, such as tall fescue (or some ryegrass cultivars).

Liming to adjust pH if necessary can be done any time now ( if you are using urea, wait at least a week before putting he lime on).

Mid to late Autumn
Usually still warm, but usually with reliable rain. Perennial ryegrass grows strongly once the weather cools, as does tall fescue, cocksfoot and brome.

If you haven't already thought about it, now is the time to think about sward species composition, and especially how to increase winter and summer active species. Check the amount of paspalum in the sward. It may perform well now, especially if it is a bit dry, but it provides little winter feed. The same applies to kikuyu. If conditions in autumn are right (cool enough to slow kikuyu growth down, heavy rain and moist soil) annual ryegrass can be sown into a very hard grazed or severely mown kikuyu sward and paspalum dominated sward for additional winter and early spring feed.

Now is the absolutely critical time to sow winter active perennial ryegrass or phalaris so that it is well established for the mid-winter 'feed pinch' and the additional feed requirements of the early spring lambing season. Prairie grass and yorkshire fog are not as winter productive as phalaris or rye, but nevertheless produce moderately well in winter. Selected annual ryegrass cultivars will provide prodigous amounts of winter feed, but they are only a temporary sward component. Lightly graze areas oversown in early autumn with white clover so that the developing seedlings get the light.

If you are trying for heavier lambs for killing or sale by feeding into autumn, good livewight gain of at least 150 grams per day can be achieved by putting the lambs into inter-rows and areas that have at least 5 cms to 8 cms of actively growing leafy sward height of high feed value species such as ryegrass, phalaris, clover or trefoil. Special purpose chicory and white clover swards are probably richest. These larger lambs need to be gorging on prodigous amounts - 4-6 kgs - of fresh lush highly palatable feed a day to achieve these weight gains (about double the amount needed to 'flush' a breeding ewe before mating). Growing larger lambs at this time of year uses a great deal of sward resource, a resource that might be better left as a 'feed bank' for the winter pasture 'pinch' when every available bite is needed for the pre-birth and the post-birth lactating ewe.

A warm wet autumn and lush clover growth can lead to bloat - especially if growth is coming off the back of a dry spell and there is a high white clover component in the sward. Lush ryegrass re-growth also seems to trigger a need for coarser browse. Sheep may be looking for tannins at this time, so be aware that thin, less corky bark may be scraped from trees - especially stonefruit and tamarillo. Lotus commences into growth about now, and it can provide the tannins needed. Alternatively, cut foliage of trees such as pittosporums, white mulberry, or loquat; or provide dedicated areas with high tannin sulla. Chopped astringent persimmon fruit are also high in tannin.

Some autumns can be unexpectedly dry - verging on drought in some instances. Don't be tempted to severely graze areas of sward - graze lower than about 25 mm (near the limit that sheep can graze to) and the growing points are damaged, and the regrowth needed for winter (once rains come) will be much slower. Tall fescue should be grazed no lower than 4 cms. If you suspect that you won't have enough winter feed, get rid of surplus stock or empty ewes, buy in hay, or start training your sheep to eat sheep pellets (a tiny amount of molasses on them can tempt them to have that first 'try' of an unfamiliar food).

While excessive nitrate levels is not a problem in the coming winter, autumn warmth may lead to sub-acute nitrate levels if there has been a dry spell which is then broken by rain, with a sudden burst of pasture growth. Sub acute toxicity can cause abortion in ewes. Be cautious.

fertiliser
Now is the time to encourage as much winter active grass growth as possible before the winter lambing season. If superphosphate wasn't applied in early autumn, apply it now to stimulate the legumes in the sward to grow strongly and fix nitrogen for grass growth before winter cool slows clover down to the point of uselessness. Superphosphate dressings can be given to newly established grass seedlings if it wasn't done earlier. While white clover produces precious little surplus nitrogen to stimulate winter grasses when temperatures are below 10^oC, winter grasses are quite able to grow and respond to nitrogen in temperatures as low as 5^oC. To compound it, biological activity that would release nitrogen from soil organic material slows right down. Unless there is a substantial 'feed bank' of 'locked up' well grown autumn pasture saved for winter feed, feed can only come from keeping winter grasses active in the coming coldest months. The key is readily available nitrogen beyond that available from urine patches. The response is a little slower as the weather cools slightly, starting a little more slowly, and tailing off slowly; in any event, whatever winter grass growth response can be had is dependant on adequate soluble nitrogenous fertiliser (urea) being applied now. If grass seed was sown heavily, it is likely to become nitrogen deficient at this time. Judicious nitrogen applications will keep it growing, as long as phosphates are also available.

Apply potassium (up to about 40 gms/square metre) if soil phosphate reserves are good, but white clover seems lacking in vigor (assuming root weevils and other pests and diseases are not to blame).

Winter
Conditions for sward growth are often bad. Soils are cool, especially in the shade, they may be waterlogged, there is less daylight, less sun, more fog and wet. Casting earthworms are very active at this time. Their casts of fine sediment helping to 'glaze' the soil surface and impede drainage, and the casts smear under sheeps hooves to contribute to the mud. On the plus side, they drag some sheep manure into their burrows at a time when other decay processes have slowed right down due to the cold.

In winter, and particularly the first two months of winter, growth of both legumes and grasses slows right down. While winter active grasses such as ryegrass will grow (and respond to applied nitrogen) as long as the temperatures in the soil are 5^oC or above, clover remain more or less dormant until soil temperatures are much higher. Such consistently warmer soil temperatures don't arrive until spring (except that some well drained sunny slopes may have soil temperatures high enough to support active clover growth in winter). In the coldest conditions, if the soil temperature at 15 cm goes below 6 degrees Celsius, sward growth stops almost entirely. Feed value also falls.

As a very broad generalisation, closely cropped sheep sward has only about half the feed value in winter as in active growth in summer. As a result, relative to summer, the daily energy demand of around 11.5 mejajoules requires double the area of winter sward of at least 3 cms to meet energy needs. Putting it another way, a sward will support the flock for only half the number of days it would in moist summer conditions. Practically, when pugging, waterlogging and faecal contamination is added in, the flock will need shifting even sooner than that.

Early in pregnancy, enough feed for 'maintainance' is sufficient for a ewe, but by mid to late winter her daily nutrient requirements will have accelerated to 16 to 20 megajoules a day, needing roughly 2.6 kgs of fresh grass to satisfy. But by the time the ewes have progressively eaten down their orchard inter-row lanes and come back to the starting point, the sward may not have regrown 2 centimetres. This is called overstocking. Regrazing grasses before they have a chance to grow enough leaf to replenish their carbohydrate stores used up in initial recovery from grazing weakens the root system, slows regrowth thereafter, and reduces the ultimate lifespan of the plants. Adequate winter pastures largely determines the number of sheep that can be kept. The weeks immediately before giving birth are times of very high nutrient demand by the ewes. There simply has to be enough high quality feed in front of the now ravenous ewes that they don't have to go searching throughout the orchard for a bite (a common cause of mis-mothering of lambs).

One of the least productive times of year is also the time when high quality feed is critical. Choice of pasture species is therefore also critical. Kikuyu, for instance, becomes effectively non existant if there is a ground frost. Winter growing ryegrasses, tall fescue, and - albeit to a lesser extent - clover are key sward species at this time, as they have much higher nutritive value than other grasses, and ryegrass and some tall fescue cultivars grow well in cool weather. Tall fescue can be grazed down quite hard - to about 3 cms - but it must be allowed to grow back to at least 8 cms between grazings, or it will lose vigor. In any event, supplementary feeds may be needed to overcome winter growth deficit. If winter active grass and legumes weren't sown in autumn, winter is too late to do much about it. Similarly, it is rather late to be trying to boost pasture growth with nitrogenous fertilisers.

While ryegrass will grow so long as temperatures are above 5 degrees Celsius, if nitrogen wasn't applied six weeks ago, winter grasses will not be meeting their growth potential right now. Even so, a response to strategic nitrogen applications can be expected, albeit the amount of growth in response to the nitrogen applied is much less due to slower growth rates in cold weather.

It may be a good time to order grafted plants of the honey locust, Gleditsia tricanthos, a tree which produces large amounts of nutritious pods which fall over winter. The honey locust can produce as much as 110 kgs of highly nutritious edible pods per tree by 9 years of age in winter, and grass still grow right to the trunk. Selected seedlings will have 26% sugars in the pods. A reasonable guess estimates the pods would have twice the feeds value (ME) of good hay.

In winter, there is little concern for water for the fruit trees. But your sheep may be going hungry. Winter slows grass growth, and if there are frost, turns kikuyu brown. As sheep use their reserves and become skinny, they lose some of their resistance to internal parasites. When underfed, parasite loads that wouldn't ordinarily affect them can become debilitating, sometimes even resulting in death (if not treated in time). While ryegrass is an important cool weather sward species, be careful not to graze a ryegrass dominant pasture too low, even if feed is short, as the endophyte fungus that causes 'ryegrass staggers' is concentrated in the base of the plant (unless you have sown 'low' or 'no' endophyte cultivars), albeit concentrations are lowest in winter.

Broadleaf weeds, if not controlled in autumn, should be controlled early in winter (if necessary). See 'Early Autumn'.

fertiliser
Areas of sward that were sown to new pasture in early autumn will benefit from a light nitrogen boost; sward oversown with white clover will benefit from dicalcic phosphate, or a dressing of superphosphate.

Superphosphate in moderate amounts applied at the very beginning of winter gives a good winter growth response by winter active grasses such as rye and tall fescue. In very low phosphate soils this may be due more to having been limited by available phosphate than any nitrogen deficiency, but in most moist soils it is due to increased clover activity before the soils get too cold. If the sward is dominated by summer and autumn grasses, such as Paspalum (Paspalum dilatatum), there will be very little winter growth response.

Likewise, in the coldest part of winter the grass component of the sward is likely to be nitrogen deficient regardless of legume numbers and/or poor legume growth. There will be little additional growth of grasses no matter how much phosphate is applied unless nitrogen is also applied. (Although the legumes will start to recover, there is a lag until warmer weather before they may become predominant, large, and active enough to influence grass growth) An application of 60kgs of urea per hectare (about 2 level teaspoons per square metre) will increase pasture growth markedly, even if the soil is relatively low in phosphates. This mid winter application of nitrogen (regardless of legumes) will increase sward yield right through spring and into early summer. In contrast, - and especially in soils with low phosphate content - heavy dressings of nitrogen applied to swards that have good clover content will supress the fixation of nitrogen by the root nodules, and cause reduced nitrogen fixing activity in spring and early summer, and therefore reduced grass growth at these times. Unless phosphates are at moderate to high levels, nitrogen applied to high clover pastures may favor grasses and depress clover growth in late spring and summer. Ensuring appropriate phosphate availability, perhaps with a slowly releasing phosphate source such as fine ground phosphate rock, mitigates against this danger.

Some subtropicals (especially avocado) become somewhat nitrogen deficient at this time as root activity slows right down in the cold. Highly available potassium nitrate could be applied, to the benefit of the sward as well, but the trees will 'pick up' come warmer weather, so such dressings are only beneficial if you want to sell some of your fruit.

Late Winter and Spring
Late winter, immediately before and after lamb birth, are times when ewes have particularly high nutritional demands. The last winter month is usually a time of warmer air and soil temperatures and thus rapidly increasing sward growth. Even so, if late winter is cold, supplements may still have to be fed. If lambing has been arranged to co-incide with spring (as ideally it should), the rams should be out of the way, in poorer quality pasture. The best resources must go to the breeding ewes, especially if the late winter recommencement of sward growth is delayed.

Good pasture management - productive cultivars, well limed, good phosphate levels, ample legumes (or nitrogen fertilised) should have been set up in autumn going into winter with the payoff starting now. As a very broad estimate (variables include rainfall, temperature and soil type), a well fertilised sward, with good stock management, can produce about 60 kilograms of dry matter (the dried weight of the fresh plant material available for consumption) per hectare per day when rainfall is ample and the soil has warmed. This is equivalent to about 300 kg of fresh green sward/hectare; or 30 grams per day extra fresh growth in every square metre of sward. In a particularly warm spring, well managed pasture can produce100 kilograms of dry matter per hectare per day. This is much more than the stock numbers geared to the constraints of winter feed availability could ever eat.

In late winter and spring, 11 ewes plus twin lambs to the hectare (the normal stocking rate) eat 45 kilograms of dry matter per hectare per day. This translates to approximately  225 kg of fresh green sward per hectare per day; or about 22 grams per square metre of sward per hectare. Thus, under average conditions of some warmth, moisture and fertiliser, and with cool weather active grasses such as ryegrass, ewes with twin lambs stocked at the conventional rate can meet their nutritional needs and still leave 88 kg of daily new growth per hectare uneaten - and even more in a warm spring. Tall fescue cultivars which head early in spring need to be grazed quite hard (down to about 5 cms), or they will have fewer tillers available for later in spring and summer, and plants will start to become lanky and the leaves less nutritious.

Conversely, cold snaps at this time of year are a fact of life. Cold rain drops soil temperature, and can stall pasture growth for days.

Mid spring is generally the time when desperate famine turns miraculously to plenty - it is usually characterised by the largest and most sudden growth flush of the year; some of which will be used by the rapidly growing lambs. If most of the orchard rows are in ryegrass and clover, there will probably be an excess of feed. But this excess doesn't provide much long material for a mulch to 'lock in' springs soil moisture to help the most vunerable fruit trees survive summer dry. Surface rooting orchard trees such as citrus and feijoa may be better with taller grass species in the inter-row sward.

Lambs should have high quality pasture as well as access to highly nutritious ewes milk. If the spring growth is not as good as hoped, it might be possible to arrange a lamb sized gap under a fence to an adjacent orchard row with good feed. This way the lambs get the best pick. Lambs gain weight significantly faster when they have good access to clover. Once they start eating significant amounts of sward they will suddenly make quite an impact on the speed with which an inter-row area is eaten out. As they eat about 2% to 4% of their bodyweight in dry matter terms a day, it is best if the pasture is as nutritious as possible.

If winter showed that you don't have enough winter active species in the sward - and also thinking about summer to come - you may want to renovate some of the orchard inter-rows with combined winter and summer active species such as tall fescue. Or you may want to sow a 'dedicated' row of a strong winter feed combination such as a selected winter active white clover and a festucalolium cultivar, perhaps with some phalaris mixed in. Seed can be sown once the soil has warmed in early spring. Springtime, with its relatively assured rains and ample feed, is a good time to take an inter-row or paddock out of the grazing rotation for the six weeks or so necessary to establish newly sown grasses and herbs.

Fertiliser
Apply a good dressing of superphosphate in late winter (for preference) or early spring to stimulate the legume component of the sward and thereby provide nitrogen for spring grass growth. Whatever quantity used, better results are achieved if it is split into a dressing now and another in autumn. Apply the second half (200 kgs/hectare or roughly 1 and a quarter tablespoons a square metre) of the split heavy (400kgs/hectare) dressing used to build phosphate reserves in low phosphate soils. 

Lush spring growth may be low in animal-available magnesium. If foliage magnesium is somewhat low, and if heavy potassium dressings has been applied, it may predispose lactating ewes to 'grass staggers'. It may be prudent to apply dolomite lime (180 kg/hectare), serpentine super (400 kg/hectare), or other magnesium fertiliser to the sward as a precautionary measure. 

If the sward lacks a decent legume component it is not too late to apply nitrogen, so long as heavy applications (400kg urea/hectare) are avoided, as there is some evidence that heavy applications may suppress clover post-winter stolon regrowth. Response to applied nitrogen usually takes about 6 weeks, so the soil has to be warm enough in late winter for a good mid spring response. Looking ahead to mid summer, if you lack a strong legume component in the sward, it would be wise to apply nitrogen in mid spring to build up grass vigor in preparation for a feed bank to carry the sheep as long as possible into summer. Kikuyu, in particular, can produce an initial growth response of an extra about 800kg of dry matter per hectare when dressed with 100kg urea per hectare. Using 200 kg of urea/hectare nearly doubles the quantity of first growth.

Apply extra phosphate and dolomite lime to areas that will be sown with clover this coming autumn. Avoid liming near citrus, or use judicious amounts of calcium sulphate.

Early spring is, in general, the best time to put fertiliser around nut trees, and pip and stone fruit trees. The nutrients are washed in by spring rain; deciduous trees will be leafing out at the end of the first month of spring; and soils are warming, promoting growth. Subtropicals need multiple small dressings throughout spring, nothing in summer (unless wet), and further dressings in autumn. A typical 'orchard mix' contains, by element, 5% nitrogen, 5% phosphate and 5% potassium. This lower analysis fertiliser is broadly suited to nut trees, pip and stone fruit. It is also suitable as a 'baseline' dressing for subtropicals, but only the sulfate form of potassium salt should be used. This fits in well with fertilising the sward. Clover is only just becoming active in early spring and therefore the sward could use a boost of nitrogen from urea, and early spring is also a suitable time to apply superphosphate. But, while the rows of fruit and nut trees will need a potassium component in the mix, potassium is best left out when dressing the sward in the inter-row, in order to help prevent triggering a potassium induced magnesium deficiency in the lactating ewes. (Potassium can be applied in autumn.)

Pelleted compound fertilisers may have a higher concentration of nutrients, especially nitrogen and potassium, and typical analyses might be 12% nitrogen (often in a mix of fast and slower release forms), 5% phosphate (most in a water soluble form for an 'instant hit') 14% potassium (almost always in the sulfate form so it can be used on chloride sensitive plants like raspberries). These fast acting but slow dissolving pellets are ideal as monthly 'supplemental' feeds for subtropicals through spring and autumn.

Trees that require reliable prescence of trace amounts of boron (apples, apricot, plum, pear, avocado) may benefit from having boron supplemented superphosphate applied - particularly on sandy soils, where boron is apparently relatively easily leached through. Boron is not required for animal health, and has extremely low toxicity, so once rain washed, pasture is safe to graze at normal superphosphate amendment rates.

Fruit trees may need additional urea (for example citrus) or potassium (stone fruit on sandy soils). It can be useful to allow grasses to grow right up to the trunk of the trees, at least until about midspring. Grass can help shade the soil from drying out in short dry spells. Nitrogenous fertiliser is partially captured by the grass, and so long as it is later sprayed out while still green and lush it will both release the nitrogen it has taken up as it decomposes, and briefly become mulch for late spring, at least.

Late Spring and early Summer
Ryegrass, a cool season grass, puts on its greatest growth at air temperatures of about 18^oC. White clovers' maximum growth happens at 25^oC. Late spring/early summer is the time when these two species growth rates are most closely matched. As a result, the clover content increases markedly at this time. The increased nitrogen from the clover, coupled with the increased biological activity/organic nutrient recycling in the soil, results in greater grass growth.

Sward at different stages of growth has greater or lesser amounts of available energy. Some potentially useful energy from the digestible part of the plant will be lost in the urine, and some otherwise usable energy will be lost from methane evolved in fermentation in the rumen (and some pasture species result in more methane than others). Once these losses are discounted, the amount of energy a sheep can extract and metabolise from a unit of dry matter is the available 'metabolisable energy'. In the warm, well-watered conditions of late spring and early summer grass feed value is particularly high, but rain often starts to tail off in early summer. As grasses mature in the drier weather the amount of metabolisable energy available to the sheep in every kilogram of grass dry matter drops by about half. This is mainly due to the tillers sending up rather coarse flowering stems which soon become 'strawy' as the seeds mature. The relatively large lignin components in these stems can't be digested.

If the inter-row sward has a good component of taller grass species such as cocksfoot and tall fescue, they should be kept grazed to discourage heading for as long as possible. But once grass tillers have started to elongate their stems, the growing point, previously near ground level, becomes vunerable to being eaten. Grazing at this point will kill the tiller, because the regrowth-point is gone. At this 'early jointing stage' the ground level basal buds are fairly inactive, as the plant is concentrating on elongating the stems of existing tillers for the annual reproduction effort. As a result, regrowth is poor. Mowing or grazing once the grass has headed is no problem, as the grass is then usually ready to revert to the vegetative phase, and quickly initiates new basal buds and leafy tillers with 'compressed' unelongated stems.

In 'wild' endophyte-affected tall fescue pasture, the endophyte fungus is most active near the crown of the plant. As a result, the vasoconstricting alkaloid 'ergovaline' is most concentrated here (it is not very soluble, so relatively little is present in the leaves). Don't let the sheep graze too low, or they ingest too much alkaloid and suffer greater heat stress than would be caused by rising spring temperatures alone. Some sheep will suffer mild intestinal inflammation, with resultant scouring (diarrhea). In ryegrass, the alkaloid 'lolitrem' is also present, and the alkaloid in the incipient basal flowering tiller is carried up with the flowering stem as it elongates in early summer. The amount of alkaloid produced increases as the season progresses into summer, making careful grazing of wild endophyte infected tall fescue and ryegrass very important. (the other common sward grass beyond Festuca arundacea and Lolium spp that hosts potentially anti-nutritive endophyte fungi is Festuca rubra). Sheep will avoid affected ryegrass, in particular, where they have the choice. If the uneaten patches are not mown or sprayed out, they will eventually come to dominate the sward - a most undesirable effect. If excess sward is available, these 'least preferred patches' could be sprayed out and re-sown with endophyte free fescue or ryegrass, novel endophyte fescue or ryegrass, or other grasses species that are naturally never infected with 'antinutrituive' endophyte - grasses such as Poa, Bromus, Dactylis, Phleum, Anthoxanthum, or Agrostis (e.g. Kentucky bluegrass, prairie grass, orchard grass, timothy, sweet vernal or browntop. )

Some areas of tall grass can be left ungrazed for cutting for orchard mulch. At least one good cut of 'locked up' tall fescue and similar grasses can be had for mulch in late spring, and the leafy new re-growth makes good sheep feed moving into summer as ryegrass comes off its peak of productivity. This may be the last chance to have a burst of leafy sward at its best, before seed heading starts. If the sward has a good legume component, or if it had nitrogen applied in mid spring, it should grow away again strongly as a 'feed bank' for summer. Late spring is the beginning of white clovers main growing season. Ideally, it would be left to build up reserves and rebuild leaf size before it is grazing more regularly going into summer.

If the greatest amount of cocksfoot is needed for summer feed, it will grow well now if allowed to grow to 20cm at the very start of its seasonal flush (early summer). When it is grazed, it should not be taken lower than 5 cms before being left again. Kikuyu, however, needs to be grazed hard - to two leaves per tiller - if it is to maintain its leafyness and quality at this time and going into summer. Rank kikuyu has less feed value.

If  red clover is being grown as an important summer feed, it will grow well now if allowed to grow to 20cm from the start of its seasonal flush in early summer. When it is grazed, it should not be taken lower than 5 cms before being left to regrow again.

But with a good chance of a dry period - and therefore a moisture deficit - in early summer, sward growth rate can easily halve. Grasses attempt to 'run to seed' starting from about mid spring, and strongly in early summer. As a consequence, in a dry early summer, the feed value of the grass that does grow starts to fall away.

fertiliser
If clover vigor is low in spite of good phosphate levels, apply moderate (30 gms/square metre) amounts of a potassium fertiliser. Use light to moderate applications of potassium because grass magnesium levels are often low at this time of year (anything from 20% to 50% lower than in autumn), and heavy potassium application can result in high potassium levels in the grass. These higher pasture potassium levels interfere with the sheeps ability to absorb the (already seasonally reduced) magnesium in the foliage.

If legumes are weak or few, and if no nitrogen has been put on in the previous month or so, and if soil and weather conditions are right, it would be worth applying a nitrogen dressing to accelerate production of high feed value nutritious fresh leafy growth. Avoid applying nitrogen to perennial ryegrass with 'wild type' endophytes (i.e. 'run of the mill' ryegrass cultivars were sown, not endophyte free or novel low alkaloid endophyte infected cultivars) as high nitrogen staus in ryegarss is implicated in increased risk of  'ryegrass staggers'.

Summer
Summer is a time when there is potential for large amounts of nutritious legumes (for example, summer is white clovers main season of growth and flowering, given adequate and regular rain or irrigation). But, in the absence of irrigation, the potential is only rarely realised, as erratic and insufficient rain more often than not creates a moisture deficit that halts white clover growth . Production is pretty much a function of rainfall and can vary hugely from year to year. Summer is when grasses are insistantly going to seed, and little can be done to stop them, although 'topping' the seeding sward delays it. Once seeding is 'out of their system', grasses become vegetative again, to build up reserves for next seeding season. But, as with clover, post-seeding vegetative grass growth is rain dependant. In a typical dry year there is not much growth. In a wet summer post-seeding, high quality grass growth abounds. Seeding ryegrass has particularly high levels of endophyte toxins, and may cause scouring or have neurological effects.

Lambs, being smaller, need less feed to simply maintain body weight. But for a newly weaned lamb (say 20 kgs or so) to grow well (100 grams plus increase in liveweight per day), the sward needs to be able to provide the equivalent of slightly more than the maintainance feed requirements of a 50 kg ewe. As the lamb gets bigger, its daily feed requirement for both growth and increased energy supplies for its bigger body increases. By the time it can be sold in summer or early autumn, say at 30 kg liveweight, the sward needs to be able to provide around 3 kgs to 4 kgs of fresh pasture a day to the now large lamb if it is to continue to grow even larger (it can maintain its weight without further growth on less). It can be seen that while the heavy pasture dry matter demands from the lactating ewe start to decline toward the late spring, the demands on the sward from maturing lambs are high right into summer. In fact, they are close to equivalent to the daily needs of a small ewe. If the summer is dry, the needs of the orchard and the needs of growing lambs clash.

 The larger home orchardist is primarily concerned with keeping the trees in good shape through the dry - especially if irrigation isn't available. Thus, while the farmer cuts and stores the grass for hay, a home orchardist, if a mower is available, is more concerned with using the grass to mulch the trees. Mulch is a precious commodity, and even with rank spring growth, it never seems to produce enough mulch to do all the trees. When there is not enough grass for both sheep and trees, buying in some bales of hay for summer feed may be an answer. In any event, don't be tempted to severly graze the sward - lower than about
3 cms and the growing points are damaged, and the autumn regrowth needed for conditioning the ewes for mating (once rains do come) will be much slower. Overgrazed summer swards tend to result in shorter and weaker grass roots, and death of the weakened suceptible grasses. Bare patches result, which, come autumn rain, become broadleaf weed patches. In severe drys, even dry resistant species such as tall fescue should be left ungrazed if possible to ensure their survival.

This is, of course, the counsel of perfection. Sheep will graze sunny areas very hard, while leaving other areas, such as in the shade, merely 'nipped'. Leaving them in the paddock in the hope they will eat the longer grass in the shade is futile, as they will simply take the short grass further 'down to the deck'. As the soil becomes very dry, their urine burns out patches. As always, dung patches will be avoided, creating numerous islands of relatively lush grass that will not be eaten unless very hungy. The decision to move the sheep out has to be made on the balance of how much damage is being done in the sun versus how much 'wasted' grass is there in the shade.

The summer post-weaning-period sward quality is critical to growth. If the sward is 'feral endophyte' perennial ryegrass or 'feral endophyte' tall fescue dominant and has little clover composition, conditions are set up for 'illthrift' due to endophyte toxicity in these grasses in the event of water stress. The effect is exacerbated if summer has been wet, promoting ample growth, followed by a dry early autumn. Lambs heat stressed by the effect of endophyte toxosis tend not to eat as much, and their immune system is weakened, lowering resilience and resistance to worms. They have poorly developed worm resisistance in the first year of life, and need high quality pasture to repair damage to their gut from parasites. At the time they most need to be eating good quantities of high quality pasture, the endophyte effect inhibits their appetite. Little can be done about it now, but it underscores the need to incorporate endophyte free or novel endophyte perennial ryegrass and tall fescue in the sward, and work on increasing the clover content.

Extending sprinkler irrigation for the orchard rows so the interow sward is also irrigated is an excellent solution if it is affordable. Irrigation is as good as early autumn rain in relieving moisture stress on endophyte containing grasses, and dramatically reduces or eliminates the risk of endophyte fungus toxicity. Failing irrigation, in exceptionally dry years, or where there is no endophyte free sward to shift the sheep onto, supplements may have to be fed.

A 25kg bale of good hay is about 80% dry matter, containing 720 megajoules of metabolisable energy (there are about 9 megajoules of metabolisable energy per kg of dry matter in good hay). As an average ewe needs roughly 10 megajoules a day to maintain its body weight, about 1.4 kg of good hay a day will meet that need. Therefore, a bale of good hay will feed one ewe for about 18 days in summer (or in winter). However, this is a large amount of dry feed for a sheep to eat (let alone a lamb), and while some breeds will eat enough hay to meet their energy needs, other breeds may not eat sufficient quantity. Sheep pellets and other concentrates are a useful supplement, as they usually have about 13 mejajoules per kilogram, but sheep usually need to be trained to accept them, and they should be fed with hay or other roughage anyway.

The strategies available to the home orchardist sheep manager are few -
1. Destock. Anticipating summer dry, sell or kill lambs in December or January when things are getting tough (early lambing is an advantage). If you are running old or cull ewes you will have to put the tough mutton in the freezer, or find a local agent willing to buy a very small number of low value ewes. 

2. Move the sheep to a conserved pasture. You may have drives, areas around the house, a small forestry lot or similar that has some 'step - through' feed. Or you may have a moist lower pasture area that you have rested for the summer feed shortage.

3. Use supplementary feeds. Most larger home orchards aren't big enough to make hay, and have already converted it to mulch for the prime concern, the fruit trees. But hay can often be bought relatively cheaply in early summer and will do for both summer dry and winter feed shortage. Many willow shelter species are palatable to stock, and these can be trimmed for summer feed (never ever use conifer trimmings - some are lethal to stock). Odd corners - or even steep unusable faces - can be fenced off and summer and winter pod-bearing trees planted. Drought tolerant tagasaste is very nutritious, and can be grown in a hedgrow close (not too close) to fences and cut for emergency feed. 

4. Sow, or encourage, more drought tolerant grasses and herbs.
When the soil is dry, the roots in the upper soil zone become inactive. Roots in deeper zones of the soil will become more active, and are able to actively take up nutrients such as phosphate if they are available at deeper levels. However, as the soil profile dries out, only the most deeply rooted grasses and legumes can continue to produce. In extended drought, only extraordinarily deep rooted lucerne and chicory are likely to remain green.
Tall fescue - very deep rooted, ideal for dry sandy or volcanic soils, can be grazed at approximately 10 day intervals, bouncing back well in between. But it's very vigor means it has to be relatively intensively grazed or it will tend to get away. Sow novel endophyte, or endophyte free varieties.
Cocksfoot  - deep rooted, usually upright, but there are prostrate cultivars particulalry suited to sheep grazing
Red clover - has a tap-root, so survives drought better than white clover, and, especially if superphosphate was applied in late spring to give it a boost, continues growing where white clover closes down. Unfortuneately it is not very persistant, often fading out of a mixed sward by about the fourth year.
Chicory - selections of this herb are renowned for producing high quality sheep feed over the warmer part of the year. It can be grown alone or combined with grasses and with clover. On the minus side, it only persists for 3 to 5 years, needs some care in getting it established, and prefers a fertile, well drained soil.
Plantain - tolerates low fertility soils, but unless modern cultivars are bought, it is a semi-prostrate rosette forming plant, so it takes up a in inordinately large area relativ