Best practice pasture renewal

Best practice pasture renewal

30 January 2018

Renewing pasture can have a significant impact on production and animal health. While it’s true pasture renewal involves a significant investment, the ongoing returns can make it well worthwhile. New grass can grow more on the shoulders of the season and may be leafier, higher in Metabolisable Energy (ME) and more palatable, resulting in more milk and faster liveweight gains. Renewing pasture with appropriate endophytes can also impact animal health, reducing both parasites and ryegrass staggers.

Plan well in advance

Identifying which pastures to renew is your first step. The Pasture Renewal Charitable Trust (pasturerenewal.org.nz) has great resources to help farmers score pasture condition and analyse the costs and benefits of renewal. Ballance Forage Specialist Murray Lane recommends farmers start as early as possible by getting soil tests done on the selected paddocks to check pH and nutrient levels so base fertiliser and lime can be applied accordingly. “It takes time to make adjustments, particularly to pH. Lime needs 12 to 18 months to do its job. Early paddock selection also allows you to plan a re-grassing program that includes two autumn sprayouts and a period with NO clover. Getting this groundwork right will pay off in the long run,” says Murray.

Use your planning time to get advice on the best grass cultivars and clover varieties for your farm and feed budget needs. Think about flowering dates, diploid versus tetraploid and, especially, what endophyte is best.

Choose your method

There are several options for re-grassing. You can sow perennial pasture in autumn or spring following a forage crop and/or winter ryegrass. Farmers in the northern regions of the North Island should note, however, that spring sowing is not recommended due to black beetle issues there. If you plan to sow pasture following a crop, you will need to replace the nutrients removed by the crop, particularly potassium.

You can re-grass by going from pasture to pasture. “However, if you’re sowing in autumn, be aware soil moisture may be depleted and one sprayout will not control perennial weeds as effectively as two,” warns Murray. “These issues can be addressed by sowing after a two-spray summer fallow. This is a very simple, low risk process which uses two sprays and effectively stops transpiration if done well.”

Your establishment method also needs to be considered. Unless winter grazing has damaged your paddocks, minimum tillage is best to maintain soil structure, moisture and worm numbers.

Off to a good start

Whatever approach you choose, germinating seeds need immediate access to key nutrients. Phosphorus, for example, is essential for early root and shoot development, but it is not very mobile in the soil. Nitrogen is also important to encourage greater tillering and leaf expansion. The quicker the canopy cover develops, the fewer problems you will have with weeds. “When drilled adjacent to seed, di-ammonium phosphate (DAP) puts nitrogen and phosphorus exactly where it is needed for this crucial early development phase,” says Murray.

Monitoring for weeds and pests is particularly critical in the first eight weeks. “Watch closely and act quickly for best results,” says Murray.

Timely grazing

Graze new pastures earlier rather than later to keep the sward open, let sunlight in and encourage clovers. “Check with a pluck test from around six weeks after sowing,” says Murray. “If the grass tears when tugged it means plants are firmly rooted and grazing animals won’t uproot them.” Graze with light stock or limit grazing time to prevent pasture and soil damage.

Nurture with nitrogen

Clovers take up to 18 months to re-establish in new pasture and fix sufficient nitrogen to supply themselves and their companion grasses. “Use SustaiN to apply nitrogen after each grazing to encourage tillering, reduce weed competition and promote a healthy sward,” says Murray. Around 55-75 kilograms of SustaiN per hectare (25-35kg N/ha) is enough.

Pasture is the most cost-effective form of feed and, given the return on investment from pasture renewal can range from 10-35 percent, it is a strategy that can make a real difference to your bottom line.

Article supplied by Ballance Agri-Nutrients