Acceso usuarios
Wheat yields are highly variable in northern Australia because rainfall is variable. Economic benefits from applying nitrogen fertilisers are uncertain because yield responses depend on a good supply of soil moisture during the growing of the crop to provide a high potential yield. While an experiment in 1996 indicated that up to 90 kg N/ha of N fertiliser is profitable, it was not known whether this response is reliable or typical. A crop model and historical climate records (1960–1993) were used in this study to produce a long-term record of yield and grain protein responses to N fertilisers. Responses in 1996 are shown to be atypical due to the favourable conditions in that year. Under typical growing conditions, it is not economic to use N fertiliser. The simulations quantified the relationship between responses to fertiliser and the amount of soil moisture available at sowing. Applications of N fertilisers will be most profitable if used when measurements indicate that the plant-available soil moisture content before sowing is above average.
