Keywords: Boundary line model, Environmental pollution, Fertiliser efficiency, Nutrient interactions, Sustainable fertiliser use.
Sustainable fertiliser use and sustainable agriculture are inseparable concepts, governed by similar considerations. In the developed world fertiliser usage is currently being restricted in order to reduce agricultural surpluses and to minimise environmental pollution. In the developing world attention is also being focused on the use of low-input systems of farming; but in this case the objective is to increase food production as efficiently and as cheaply as possible. However, there is little doubt that if agriculture is to meet consumer demands both now and in the future, fertiliser inputs will have to be sustained at fairly intensive levels on much of the land currently used for food production. Low-input systems of farming would simply be incapable of supplying the food requirements of an ever-increasing world population, and might actually lead to the demise of the agricultural industry. However, it is also clear that Ã¢â‚¬Ëœintensive’ farming practices would be equally unsustainable if the pollution problems associated with high levels of N fertiliser usage were to remain unresolved. A major issue facing agriculture worldwide therefore, is the need to improve fertiliser efficiency and particularly N fertiliser efficiency.
Various strategies have been adopted to improve N fertiliser efficiency; some have involved the use of chemical additives; others, better management techniques. The most successful strategies, however, are likely to be those in which a range of different technologies and management practices are combined to give integrated Ã¢â‚¬Ëœblue print’ packages. Such packages would exploit the potential of the individual components to interact positively or synergistically; in this respect interactions between nutrient factors could have a significant role to play. Unfortunately, these phenomena have largely been under-researched owing to the difficulty of identifying and studying them in isolation from other confounding nutritional effects. In this paper a new approach for studying crop responses to nutrients and to nutrient interactions is outlined, which is based on the boundary line model of Webb. This model provides a means of delineating the effects of specific nutrient parameters on crop production from other confounding background effects, and has the potential therefore to re-evaluate critical nutrient values for different crops, and to produce a definitive crop response model: it could also have a key role in identifying new strategies for resolving the problems of N inefficiency in agricultural systems.
J S Bailey, Dept. of Agriculture for Northern Ireland and the Queen’s University, Belfast, UK.
43 pages, 14 figures, 5 tables, 72 references.