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The choice of plant species and cultivar play a major role in maximising the life of pasture, the amount of feed available for cows and ultimately the amount of profit from every hectare of pasture.
Why does pasture renewal matter?
Pasture renewal is important for increasing pasture productivity and long-term farm profitability. Replacing poor-producing pasture is one of the simplest ways to invest onfarm for a significant and relatively predictable rate of return.
Pastures can grow indefinitely but, over time, factors such as drought, pests and pugging will cause pasture to deteriorate with these adverse effects:
• Total dry matter production drops
• Desirable species decline
• Weeds increase
• Feed value reduces.
Benefits of pasture renewal
• New pasture is significantly more productive.
• Control over seasonality of production.
• Higher metabolisable energy.
• Access to new endophytes developed to solve regional problems, such as resistance to pests and diseases, and greater tolerance of drought.
• Cows on new pasture graze more grass, resulting in more milksolids production and/or faster liveweight gains.
Identify poorest paddocks
Your poorest-producing paddocks are the best ones to renew. That’s because they have the greatest potential for improvement, as long as underlying negative factors such as drainage problems and pests are addressed.
Use grazing and yield records to identify your best and worst paddocks. The more measures and assessments you have for comparison, the better and easier it will be to make decisions.
Farmers without accurate records may want to use the Pasture Condition Score Tool. Developed by a DairyNZ-led industry group, this tool outlines a plan for assessing and ranking paddocks based on the extent of damage from pests and pugging. Check it out at dairynz.co.nz/pasturetool.
Get establishment right
If you want high quality pasture, you’ll need to spend time planning ahead and preparing soil before you start sowing. There are several key steps to consider.
1. Early sowing date
The first step in your preparation is to think about when to sow seed. In most districts, it pays to have seed in the ground by March 31, provided you've given attention to moisture retention in the seed bed. Sowing later means you'll face a greater risk of pasture damage in winter and spring, reduced yield and small, less densely tillered plants coming out of winter.
2. Seed bed preparation
A fine, firm weed-free seedbed is ideal for plants to become established. Many farmers overlook the important step of rolling their seedbed to achieve consolidation prior to sowing. A consolidated seedbed conserves moisture and makes it possible to achieve the correct sowing depth, especially with a seed drill. Without consolidation, you may end up with a soft seedbed where wheel tracks are pushed down and coulter depths vary, leading to uneven seed depth and establishment.
3. Seed sowing rate
You also need to decide how much seed to spread. There is no ‘correct’ ryegrass seed sowing rate for NZ farms; the appropriate sowing rate will depend on your sowing method.
Both a standard and lower perennial ryegrass sowing rate can work well but lower rates need to be well managed.
4. First grazing
Pastures grow slowly until they are ‘nipped off’ at first grazing, which accelerates both their growth rate and tillering.
To decide if a pasture is ready for its first grazing, make sure it passes the ‘pluck test’. This is where you check the plants are firmly rooted in the soil. If you can’t pluck them out by hand, they’re ready for grazing.
Careful summer management
Follow these tips for managing pasture through its 'yearling' establishment phase.
• Graze for the first time only when new seedlings cannot be pulled out by hand plucking. This is usually six-eight weeks after sowing.
• Graze consistently to the same residual through the first winter and spring, leaving 4.5-5.5cm in height. This encourages growth and tillering of new ryegrass plants and helps avoid shading and suppression of white clover seedlings (as well as maintaining pasture quality).
• Graze consistently at the same pre-grazing mass (2800-3200 kilograms of dry matter/hectare depending on type of pasture). Letting a pasture get too long, particularly in late spring, reduces its density by shading out daughter tillers.
• Do not make hay or heavy crops of silage from new pastures in their first year as this damages plants (reduces tillering and root growth).
• New pasture responds well to nitrogen so make two small applications of about 25-30kg of nitrogen/hectare over the first six months when conditions allow (i.e. not water-logged and soil temperature is above 7°C).
• To be considered successfully established, a pasture must be dense, well-tillered and have survived a summer. Pasture management through summer has a major impact on future performance.
For further information visit dairynz.co.nz/pasturerenewal.
*Look out for this article and other interesting on-farm management stories in Getting the Basics Right 2018 issue arriving in your mail boxes soon.