Having last year's yield maps is one thing but what we really want to know is what this year's yield map will look like. At the recent GRDC Research Update at Rutherglen, Dr Daniel Rodriguez had exciting information about trials designed to do just that.

With the aim of marrying nitrogen fertiliser management to crop needs without ignoring rainfall, the Future Farming Systems project aims to take remote sensing and precision agriculture a step further. Analysing five years of yield maps from a Birchip Cropping Group paddock, Dr Rodriguez said that the DPI precision agriculture team had identified not just high, medium and low yield areas but 'flip-flop' areas where yields are high or low in different seasons.

"It's one thing to use yield maps to identify different management zones but we found that yield over more than 60% of the paddock varied seasonally as well as spatially," he said. "Parts of what was a high production area in one year provided only a moderate yield in the next year. A starting point for the project is to identify the key drivers behind those variations."

The project combines yield maps and soil analysis including electric conductivity mapping to identify such limiting factors as salinity within each of the management zones as a means of predicting the variability. The interpretation is married to real time crop monitoring and seasonal forecasting to more precisely manage nitrogen fertiliser treatment.

"Failing to get nitrogen treatment right not only risks haying-off and high rates of screenings," Dr Rodriguez said. "We're using remote sensing tools to identify the crop's nitrogen requirements within each of the management zones to better time and target nitrogen application."

Dr Rodriguez said that three remote sensing techniques to measure light reflection and heat from the crop were being used to measure its health and to detect early signs of moisture, nutrition or disease stress.

"The problem with real-time remote sensing is that while it will sense changes in the crop canopy, it can't tell whether those changes are the result of moisture stress, lack of nitrogen or disease pressure," he said. "The early technologies established a link between the detection of moisture stress and the thermal part of the spectrum. More recent technology is allowing us to pick up the variations in moisture stress across the crop."

The wheat crop takes up to 70% of the nitrogen needed to produce the crop between the period of stem elongation and flowering. Remote sensing can provide an indication of the crop's health at this stage but the unknown factor in the equation is what the weather will be like for the rest of the season.

"Seasonal forecasting is the last link in the chain needed to get the right amount of fertiliser in the right place at the right time," Dr Rodriguez said. "We're looking at correlations between the Southern Oscillation Index in June and July and rainfall for the rest of the season. The GRDC project aimed at producing tools to reduce the impact of climate variability is producing exciting results that we'll incorporate across all our projects."