Winter Pasture Management

Mark Palmer, Stephen Pasture Seeds, Northern Victoria

Getting value from pastures is paramount to the profitability of a grazing enterprise. The start-up investment made into pastures can be significant depending on the species and sowing rate. However it is the investment made into managing pastures that governs the return on investment received, and therefore the value achieved. So what are the best management practices to achieve the full potential of your pasture? Is it simply fertiliser and weed management? Or is there more to it such as grazing management and timing of management practices?

In this article we outline the best practice winter management guidelines to achieve maximum winter and spring production from your pastures.

First and foremost for getting the most out of your pastures is ensuring adequate plant population, and limiting competition from weeds. Weeds will rob your pasture of valuable moisture and nutrients resulting in a significant reduction of dry matter production. They also offer less nutritional benefits than improved pastures, further limiting livestock performance. The ideal timing for controlling weeds is at the 2 to 4 leaf or rosette stage. It is recommended you consult a local agronomist in order to correctly identify weeds, and select the appropriate chemical and application rate.

Coming in to winter we need to be aware of the slowing growth rates and therefore rate of nutrient uptake, and matching grazing’s and nutrient input to this. Research conducted at the Tasmanian Institute of Agriculture by Danny Donaghy and Bill Fulkerson in 2001, identified that the optimum time for grazing ryegrass pastures is at the 2.5 to 3 leaf stage. Trial results showed that this is the optimum growth stage for both nutritional value and utilisation. Any earlier than 2.5 leaves and the plants energy reserves will become too depleted for optimum dry matter production. Grazing post 3 leaf stage will also reduce utilisation of dry matter, because while the 4th leaf is emerging the 1st will be dying. Therefore resulting in wasted dry matter production and under utilisation of produced dry matter.

When it comes to maximising regrowth potential, Donaghy and Fulkerson found that a post grazing residual of 50 mm ± 10 mm is ideal. Coinciding with pre-grazing leaf stage of 2.5 to 3 leaves, they found that this level of residual allows for optimum regrowth. Given that leaf emergence is mainly governed by temperature, during winter it can take between 20 and 30 days for a leaf to emerge. Therefore in order to achieve a pre-grazing leaf stage of 2.5 to 3 leaves, rotation length will be between 55 and 90 days. Given temperature is the main driver this can be highly variable depending on individual location.

In addition to grazing management nutrient management is also important.  Given the colder soil temperatures, shorter days and overcast weather, both natural mineralisation of nitrogen and plant uptake slow.  Nitrate is the primary source of nitrogen absorbed by plants.  During colder weather the conversion of urea and ammonium to nitrate slows considerably.  Resulting in the pastures response post application taking considerably longer than during warmer months.  Grazing Systems Agronomist Lee Menhenett suggests using fertiliser blends over winter that contain both ammonium and nitrate nitrogen.  The nitrate nitrogen provides an instant hit to the pastures. Whereas the ammonium is slowly released to the plant over time as soil microbes convert it to nitrate nitrogen.  Some of the blends available on the market also have the added benefits of including phosphorus, potassium, sulphur and calcium. Making them ideal all round products to increase winter production.

Setting your pastures up for winter can make all the difference to your return on investment.  Key to your pastures winter performance is weed control, grazing and nutrition management.  Get these three factors right and you will have an enviable feed wedge this winter.

References

Donaghy Danny, Fulkerson Bill (2015) Principles for developing an effective grazing management system for ryegrass-based pastures. Sourced from ResearchGate

https://www.incitecpivotfertilisers.com.au/news-and-insights/agronomic-insights/pasture/faster-pasture-with-cal-gran-aftergraze

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