How much nitrogen matches season, soils?

GRAIN GROWERS CAN now tap into a computer program designed to make decisions about wheat and nitrogen fertiliser considerably more transparent.

According to CSIRO Plant Industry's John Angus, the maNage Wheat program takes much of the guesswork out of what can be a financially risky decision-making process. (The program was designed for conditions in south-eastern Australia.)

"Many wheatgrowers now spend between $50,000 and $100,000 a year on nitrogen fertiliser," Dr Angus said. "But, while the returns from such sizeable investments can be high in a good season, in the event of, for example, a 'bobtail' spring, the bottom-line can be extremely negative."

Weather conditions were just one of many factors farmers needed to consider when deciding how much to invest in nitrogen fertiliser. "Soil factors include nitrogen status, water-holding capacity, pH and the prevalence of root diseases," he said.

"When you take into account additional crop factors like sowing date, maturity type and the level of nitrogen already held in the crop, making a correct decision about how much fertiliser you need can be a daunting prospect."

Developed specifically for dryland wheatgrowers in Victoria and southern NSW, the maNage Wheat program includes a simulation model which enables farmers to estimate the effects applications of different amounts of nitrogen will have on yield and protein levels under a range of weather and soil conditions.

The program also takes into account the characteristics of the variety of wheat being grown, when it was sown, paddock history and plant nitrogen status.

"It can be used to estimate the effects of nitrogen applied before sowing in relation to long-term weather data or tactical decisions about top-dressing made in response to the level of rainfall during the current year and crop measurements, prices and protein premiums," Dr Angus said.

"There is a database to store records of crop, soil, paddock, nitrogen cost, grain price and protein premiums, as well as a database of regional weather records for 223 locations in NSW and Victoria.

"It's a very useful tool in terms of assisting farmers and their advisers to make informed decisions but it does not, for example, account for hazards like diseases, frosts or floods."

Junee wheatgrower Bernard Hart says using the maNage Wheat program has enhanced his ability to make good tactical decisions about nitrogen management.

"It's really helped me to understand the importance of ensuring you have sufficient nitrogen in the soil at sowing time - to maximise plant establishment rates - but that using excessive amounts is highly inefficient and, ultimately, costly," Mr Hart said.

The program was developed by CSIRO with support from growers and the Federal Government through the GRDC.

The software is supplied on a CD and requires a PC running Windows® 95 or later. Available from Wesfarmers Landmark outlets throughout southern NSW and Victoria.

Program 4 Contact: Dr John Angus 02 6246 5095