You may already be regrassing a few paddocks a year, or every now and then. You’re probably aware that new grass species are more productive, but may not be sure how to introduce a higher rate of pasture renewal into your farm management programme. Perhaps you’re not convinced the investment stacks up. In this section you’ll learn about the benefits of pasture renewal, and why the upfront costs pay off.
Lamb live weight gain over 18 weeks averaged 83g per day compared to 135g per day on renewed pasture (Source, Benefit analysis/lit review, page 22, )
Stevens, D.R.; Turner, J.D. 1994. Management of finishing pastures to maximise carcass gain. Proceedings of the New Zealand Grasslands Association 56: 67-72
110g/d old pasture to 200g/d new pasture (Source: page 22, benefit analysis/literature review)
Stevens.D.R; Gibson, A.K.; Casey, M.J 2000 Improving on-farm profitability of sheep and deer systems using pasture renewal in southern South Island. Proceedings of the New Zealand Grasslands Association.62: 201-205
One Star cultivars profit from -$188/ha to -$51/ha, Five Star Cultivars $363 to $500/ha (Source: Forage Value Index - Mean differences in range of economic values between One Star and Five Star Cultivars across all regions).
Clark, C.E.F.; Romera, A.J.; Macdonald, K.A.; Clark, D.A. 2010. Inter-paddock annual dry matter yield variability for dairy farms in the Waikato region of New Zealand. New Zealand Journal of Agricultural Research. 53(2): 187-191.
What is pasture renewal?
Pasture renewal is the process of replacing older, less productive pastures with new grass and forage species, through crop rotation. Pasture growth can decline over time and the most successful approach is often complete pasture renewal. Modern forage cultivars have been bred to suit every farm type and operation. Designed to improve productivity, they also:
Resist pests and disease better
More palatable and easier
Have a higher feed value (ME) so stock do better
feed than weed grasses in winter and summer
Replacing poor-producing paddocks with new pasture is one of the simplest ways to invest on-farm for a significant and relatively predictable return. The higher your farm’s performance, the more it can gain from intensified pasture renewal. And it isn’t only for ‘high input’ farms - any kind of farm or grazing-based business can benefit from pasture renewal.
New pasture is much
Most pastures deteriorate from a number of causes - weed invasion, particularly low quality grasses like paspalum and Mercer grass, dry conditions, wet/flooding, poor fertility, poor drainage, diseases, insects, pugging, soil compaction, overgrazing and poor management.
Over time, the population of desirable, productive plants in a pasture declines, while undesirable or unproductive plants increase and pastures become ‘runout’. Old pastures produces less dry matter, are lower in ME and stock preference, and this decline compounds as the pasture ages.
Successful pasture renewal can increase dry matter per hectare per year by around 3–6 tonnes.
This is true for all farms – the extent to which the extra production can be converted into additional income varies.
Modern pasture cultivars enable farmers to choose when a new pasture will be most productive and when it goes to seed. Cultivars can be chosen to produce more grass in winter, summer and autumn than traditional pastures. Ryegrasses offer more than six week’s difference between the earliest and latest seeding dates.
Consistently higher ME
New pasture is more attractive to grazing animals, and easier to manage during late spring and early summer. And because new pastures are grazed more uniformly, it’s easier for farmers to control the quantity of residual dry matter when animals are moved. The optimum post-grazing residual means optimum ME regrowth and increased animal performance at the next productive grazing.
New pastures consistently produce an average of 0.5 more megajoules of ME/kg DM - on top of the extra dry matter produced by a new pasture. This is due to:
higher proportion of desirable species
later and more
with fewer seed heads produced
Access to new endophytes
Most new perennial ryegrass cultivars are available with new endophytes developed to solve particular problems in different regions. The endophyte occurring naturally in New Zealand ryegrass pastures – ‘standard’ or ‘wild’ endophyte – makes its host ryegrass plants resistant to some insect pests, but was found in the 1980s to cause ryegrass staggers and heat stress in animals.
New endophytes are continuing to be developed to maintain good animal health while enhancing pest resistance. As well as Argentine stem weevil, new endophytes provide resistance to pasture mealy bug, black beetle and root aphid, with more pests likely to be added to this list.
DairyNZ carried out a three-year study comparing pastures with the novel AR1 and standard endophyte – the former produced 9% more milksolids than the latter.
Better grass, better animals
Animals on new pasture graze more grass, which is leafier, higher in ME and more palatable, resulting in:
more milk production
faster liveweight gains
higher stocking rates
more contented animals.
Pasture renewal can have significant benefits for animal health. It contributes to: