Legumes for dry lands
Dry lands in the eastern shadow of the main divide of both islands typically receive only 600 to 800 millimetres of rain and experience dry summers. Successful dairying on ryegrass and quite clover pastures requires about 2m of moisture in the form of rain or irrigation, so farmers on some 4,000,000 hectares of dry lands have developed systems involving a range of feed sources. They use these at various times to provide enough feed to bring young stock up to saleable store condition before Christmas when soil moisture and hence feed supplies generally run out.
For many dryland farmers the most successful grass species is Cocksfoot, not ryegrass, because it persists through the dry periods. Although it is not very palatable in the middle of summer if there is any rain at all it will green up and recover quite quickly. White clover will generally establish well and initially has a taproot that enables it to survive. However, the taproot dies off within 18 months and the plant is left with only very small roots at the soil surface, and so does not perform in dry spells.
Lincoln has been studying a range of alternative legume species. PhD students have done the background science and Meat & Wool New Zealand has funded applied research.
The quest has been for species that might perform better when the taproot has gone, or those that will grow earlier in the spring before white clover would normally start growing. The two most promising species are subterranean clover and Balansa clover, reports Lincoln plant scientist, Dr Derrick Moot.
Subterranean clover is so named because it buries its seed in the ground for the following year. It was widely sown in New Zealand in the 1950s but has been little used since then. However, it can still be found in older pastures and so it clearly it is ecologically adapted to this environment, but we need to know how can we help it to become more strongly established, he says.
Balansa clover flowers at the top of the plant and so its grazing must be managed so that it will flower and produce seed before the stock eat the flower heads. Little is known yet about this legume, how much seed it actually produces and how often farmers need to let it reseed. Once the seed is formed it can be eaten by the stock and will pass through the gut and be deposited on the ground so that reseeding will happen.
Advantages of using sub or Balansa clovers
Typically, a dryland farmer will grow a crop to feed ewes over the winter brassicas, green feed cereals or annual ryegrass. As lambing approaches the stock are put onto whatever pasture is available. Cocksfoot has low protein and ME levels, and while ryegrass and white clover make very good feed they are not growing at this time.
However, sub and Balansa clovers grow earlier in the spring than white clover, and their presence boosts the quantity and quality of the pasture they are high quality fodder in themselves, they produce nitrogen that improves the quality and growth of Cocksfoot, and the additional nitrogen from dung and urine also has a stimulating effect.
The overall impact is to improve the feed supply for ewes and lambs set stocked after lambing. Earlier pasture growth in spring means earlier liveweight gain so that store lambs can be quit earlier, or at higher weights.
When these clovers die over summer, the nitrogen released boosts Cocksfoot growth again in autumn.
Pasture management
Lincoln suggests that these farmers should sow some paddocks in Cocksfoot and sub/Balansa clover, and so create an additional step in their feeding regime to fill the deficit between the winter crops and the ryegrass/white clover pastures that come away late in spring.
To make the most of the new legumes farmers need to:
Graze Cocksfoot pastures hard in autumn so that there is bare ground available for these clovers to germinate and grow over when the rains come. If that space is not available the Cocksfoot will out-compete them.
The newly germinated clover plants should be lightly grazed then left, perhaps grazed once over the winter, so that they will be dominant in early spring for lambing.
If the usual summer dry fails to eventuate, farmers may end up with a dense Cocksfoot pasture in autumn, which will not allow the germinating clovers enough space to grow. Holding on longer to stock may be an option in a high growth year.
Flowering time is critical, and stock should not be allowed to eat the flowers before the seeds are set. By that time the ryegrass/white clover pastures should be growing, and stock can be moved onto them or lucerne or some other crop.
Ideally, farmers should also sow a species that will perform well in summer, but since there isnt one Dr Moot suggests that is the time dryland farmers should go to the beach!
The above is likely to work well for many farmers in Marlborough, Canterbury, and the Wairarapa.
Says Derrick Moot: We are trying to get farmers to recognise that the early spring moisture they have is really vital and its supply is finite. They need to be growing the best quality plants they can at that time, and even though using these early growing legumes will boost growth and use up that water a little faster, the quality of feed produced is much greater.
This approach will help get store lambs up to weight earlier and off the property. Any animals you have to carry through the summer will potentially reduce production in the following year, so the best system is to maximise growth from September to December.
For many dryland farmers the most successful grass species is Cocksfoot, not ryegrass, because it persists through the dry periods. Although it is not very palatable in the middle of summer if there is any rain at all it will green up and recover quite quickly. White clover will generally establish well and initially has a taproot that enables it to survive. However, the taproot dies off within 18 months and the plant is left with only very small roots at the soil surface, and so does not perform in dry spells.
Lincoln has been studying a range of alternative legume species. PhD students have done the background science and Meat & Wool New Zealand has funded applied research.
The quest has been for species that might perform better when the taproot has gone, or those that will grow earlier in the spring before white clover would normally start growing. The two most promising species are subterranean clover and Balansa clover, reports Lincoln plant scientist, Dr Derrick Moot.
Subterranean clover is so named because it buries its seed in the ground for the following year. It was widely sown in New Zealand in the 1950s but has been little used since then. However, it can still be found in older pastures and so it clearly it is ecologically adapted to this environment, but we need to know how can we help it to become more strongly established, he says.
Balansa clover flowers at the top of the plant and so its grazing must be managed so that it will flower and produce seed before the stock eat the flower heads. Little is known yet about this legume, how much seed it actually produces and how often farmers need to let it reseed. Once the seed is formed it can be eaten by the stock and will pass through the gut and be deposited on the ground so that reseeding will happen.
Advantages of using sub or Balansa clovers
Typically, a dryland farmer will grow a crop to feed ewes over the winter brassicas, green feed cereals or annual ryegrass. As lambing approaches the stock are put onto whatever pasture is available. Cocksfoot has low protein and ME levels, and while ryegrass and white clover make very good feed they are not growing at this time.
However, sub and Balansa clovers grow earlier in the spring than white clover, and their presence boosts the quantity and quality of the pasture they are high quality fodder in themselves, they produce nitrogen that improves the quality and growth of Cocksfoot, and the additional nitrogen from dung and urine also has a stimulating effect.
The overall impact is to improve the feed supply for ewes and lambs set stocked after lambing. Earlier pasture growth in spring means earlier liveweight gain so that store lambs can be quit earlier, or at higher weights.
When these clovers die over summer, the nitrogen released boosts Cocksfoot growth again in autumn.
Pasture management
Lincoln suggests that these farmers should sow some paddocks in Cocksfoot and sub/Balansa clover, and so create an additional step in their feeding regime to fill the deficit between the winter crops and the ryegrass/white clover pastures that come away late in spring.
To make the most of the new legumes farmers need to:
Graze Cocksfoot pastures hard in autumn so that there is bare ground available for these clovers to germinate and grow over when the rains come. If that space is not available the Cocksfoot will out-compete them.
The newly germinated clover plants should be lightly grazed then left, perhaps grazed once over the winter, so that they will be dominant in early spring for lambing.
If the usual summer dry fails to eventuate, farmers may end up with a dense Cocksfoot pasture in autumn, which will not allow the germinating clovers enough space to grow. Holding on longer to stock may be an option in a high growth year.
Flowering time is critical, and stock should not be allowed to eat the flowers before the seeds are set. By that time the ryegrass/white clover pastures should be growing, and stock can be moved onto them or lucerne or some other crop.
Ideally, farmers should also sow a species that will perform well in summer, but since there isnt one Dr Moot suggests that is the time dryland farmers should go to the beach!
The above is likely to work well for many farmers in Marlborough, Canterbury, and the Wairarapa.
Says Derrick Moot: We are trying to get farmers to recognise that the early spring moisture they have is really vital and its supply is finite. They need to be growing the best quality plants they can at that time, and even though using these early growing legumes will boost growth and use up that water a little faster, the quality of feed produced is much greater.
This approach will help get store lambs up to weight earlier and off the property. Any animals you have to carry through the summer will potentially reduce production in the following year, so the best system is to maximise growth from September to December.