The Nitrogen book : principles of soil nitrogen fertility management in northern NSW and southern Queensland farming systems : includes easy-to-use electronic N fertiliser calculator

Declining fertility of arable soils remains a problem of national and international significance. In eastern Australia’s northern grain belt, soil erosion and nutrient removal are the main factors causing soil fertility decline. In most cropping regions of northern Australia (Darling Downs, Western Downs and northern NSW) soil fertility rundown has occurred and needs to be corrected in order to obtain satisfactory yields in good seasons because in most areas the period of continuous grain cropping has exceeded after 40-50 years. Hence the frequency response to applied nitrogen is likely to be quite high, drought years not withstanding. This manual details: • identifying causes of variability • methods to obtain a ‘target’ yield • discussion of soil sampling • alternative strategies to improve soil fertility. In this manual, outputs from crop simulation models are used quite extensively. The reader is encouraged to obtain the program WhopperCropper for their own use. WhopperCropper is an easy way to visualise the full range of yield (and gross margin) outcomes that are possible. This allows the user to choose a strategy to match a targeted seasonal outcome in keeping with the grower’s knowledge of paddock performance over a range seasons and attitude to managing financial risk