Cropping

How to boost feed growth

By Country News

With autumn producing less-than-favourable conditions across a lot of the state, many livestock producers may be going into winter with less pasture than desired.

So how can we increase the pasture growth rates across the winter period to improve how much feed we grow?

Grazing management

Did you know that you can double the growth rates of pasture through winter through the grazing management of the pastures?

A farm in Gippsland grazed two paddocks side by side in June the other year. One paddock was grazed for two days, the other had stock in for six days.

Both paddocks were strip grazed, but stock were not excluded from re-grazing the areas of the paddocks they had access to the day before.

When pasture growth rates were measured a month later the paddock grazed for two days had a growth rate of 18kg dry matter (DM)/ha/day. The paddock that was grazed for six days had half the growth rate at 9kg DM/ha/day.

Are there ways you could minimise the effects of back-grazing in the system?

Options include running temporary troughs off your main trough and moving the new strip, fencing it behind.

Alternatively, electric fencing can be used to create a laneway in the paddock back to the water source, or the strip fences can be wagon wheeled off the water point.

Urea

Another alternative to improve winter feed growth rates is applying urea.

As a nitrogen source to use in winter, urea is less prone to losses (leaching and denitrification) during the cold wet months.

If pasture is growing slowly, we would expect a response rate to the urea of 5:1 — that is 5kg of DM of feed grown for every kilogram of nitrogen applied.

So, if we applied 40kg nitrogen/ha, we could expect an additional 200kg DM/ha to be grown compared to what would have been grown without applying the urea.

If pasture growth conditions are moderate, we could expect a 10:1 response rate.

A single application of nitrogen fertiliser is most efficient when applied at rates between 25 and 50kg N/ha (54 to 109kg urea/ha).

Remember to keep the stock off the paddock for 21 days post urea application, as nitrate toxicity could be a concern if grazed too early.

■Note: When doing your own comparisons, ensure you are using a delivered and spread cost for urea.

Gibberellic acid

Gibberellic acid (a naturally occurring plant hormone) can be useful through the cold winter months, and generally the colder the day time temperatures the better the response.

During mild winters, the response to gibberellic acid can at times be negligible.

The rapid plant growth that can occur through the use of gibberellic acid is often lighter in colour, but this doesn’t affect the quality of feed on offer.

Phalaris-based pastures are highly responsive to gibberellic acid with recommended rates of application of 2.5 to 10g of gibberellic acid/100litres water.

In pastures that are dominant in perennial rye-grass, annual rye-grass or cocksfoot, it is recommended that gibberellic acid be applied at 10 to 20g/100litres water.

■Note: The responses to the use of urea and gibberellic acid are dependent on adequate moisture levels in the soil system.

If soils are not moist enough to support growth without their use it is recommended holding off on applying until soil moisture levels improve.

—Fiona Baker

beef extension officer

Agriculture Victoria