Grains Research and Development

Date: 01.06.1999

Higher rainfall/grazing Lime puts $$ in your pocket

Healthy wheat and canola crops show benefits of liming at the Neville trial site, NSW central tablelands.

Adding lime could increase your crop yield by as much as 30 per cent, and that helps your wallet as well as your soils and pastures. That's the message coming out of liming trials on mixed pasture-cropping systems at Neville, on the NSW central tablelands.

The research team, led by Ashley Mead of NSW Agriculture, set out to demonstrate that even predominantly grazing systems could profitably add lime, provided they applied it with a crop.

"It is the most cost-effective way to add lime on these acid tablelands soils, and the benefits will last about five years, well into the next pasture phase," says Mr Mead.

How and what they learned

The research team sowed wheat (Currawong) and canola (Pinnacle) into an old but reasonably good-quality clover-based pasture. It applied lime to some plots to bring the soil pH from 4.2 to a pH of around 5.5, using various methods of incorporation. Crop yields on the limed plots were then compared with those from the unlimed plots.

Changes in soil pH after adding lime, using three methods of incorporation (no incorporation, shallow incorporation, deep incorporation). The only significant difference in effect between methods was that the deeper cultivation had a greater effect on the soil pH at depth.

The result was surprising, with the greatest benefit to the soil and crop yields coming simply from adding lime, regardless of how it was incorporated.

Research at Wagga Wagga is looking at ways to better incorporate lime to depth for severe acid problems in the subsoil.

Crop gross margin

"In the case of wheat, applying lime with any of the three methods brought the crop from operating at a loss of $29/ha, to providing a reasonable profit of $81/ha," says Mr Mead. "However, once you factor in the cost of lime, at $100/ha, you still would have lost money this year, although not as much as if you had not added lime at all." (Keep in mind the beneficial effects of liming extend over 5-10 years.)

One reason for the lower profitability of wheat was the low prices received this year. Wheat also needed more chemical inputs than canola to control weeds and other pests. This meant that quite a high wheat yield was needed to break even.

Canola's advantage was clearly price, but the trials also demonstrated again the importance of a break crop such as canola for controlling weeds before going on to wheat.

Healthy wheat and canola crops show benefits of liming at the Neville trial site, NSW central tablelands.

Canola as a profitable vehicle for lime

Mr Mead suggests that with an increased gross margin of $170/ha, even after allowing for the cost of lime, growers would benefit from putting in a canola crop to cover the cost of lime before reverting to a pasture phase.

"The importance of liming cannot be overstated, even for a canola crop for which the profits without liming may look attractive, because there is a much greater risk of crop failure on unlimed soils.

"For some growers, putting in a single canola crop is actually a great option for adding lime, making money and improving their pastures for a few years."

The research is part of NSW Agriculture's Acid Soils Action initiative. Growers supported the project through the GRDC by provision of a controlled-traffic seeder which is better suited to sowing crops with a minimum of disturbance into an uneven, high-strength soil surface.

The benefits of liming winter crops are clearly shown in increased profit for both* wheat and canola

Wheat (farmgate price of $100)
Grain yield (t/ha)Gross margin ($/ha)Increased profit ($/ha)Cost of lime ($/ha)Profit after lime ($/ha)
No Lime3.9-29NilNil-29
Lime (2.5 t/ha)5.181110100-9
Canola (farmgate price of $320)
Grain yield (t/ha)Gross margin ($/ha)Increased profit ($/ha)Cost of lime ($/ha)Profit after lime ($/ha)
No Lime1.8258NilNil258
Lime (2.5 t/ha2.4428170100328

Changes in soil pH after adding lime, using three methods of incorporation (no incorporation, shallow incorporation, deep incorporation). The only significant difference in effect between methods was that the deeper cultivation had a greater effect on the soil pH at depth.Changes in soil pH after adding lime, using three methods of incorporation (no incorporation, shallow incorporation, deep incorporation). The only significant difference in effect between methods was that the deeper cultivation had a greater effect on the soil pH at depth.

Program 3.5.2

Contact: Mr Ashley Mead 02 6342 1333