Soil Guideline

Sustainable Nitrogen Management in Agricultural Practice

Nitrogen is an essential element for plant growth limiting food production and plant protein content, which are key issues in feeding the world population. Since nitrogen fertilisation is highly correlated with crop yields, growers usually apply large amounts of nitrogen fertiliser to obtain high yields of good quality. From an economic perspective, this may be a reasonable decision, but from the environmental perspective it is not, since the environmental pollution with surplus nitrate is almost inevitable. This unnecessary surplus of nitrogen contradicts one of the key aims of today's agriculture, namely sustainability. One of the definitions of sustainable is "capable of being maintained at a steady level without exhausting natural resources or causing severe ecological damage".

Currently many agricultural systems in the Arab region, especially intensive vegetable production, are not sustainable in this way causing severe ecological damage. Possible consequences are surface- and groundwater pollution with nitrate, leading to an increased health risk. While the achievement of a truly sustainable production resulting in lower yield and revenue is unlikely considering the costs involved for the farmer, a minimum goal should be the avoidance of over-fertilisation.

The avoidance of over-fertilisation may also be a benefit to farmers and consumers. Over-fertilised crops can be more susceptible to disease, or may have elevated nitrate levels in vegetable tissues thereby posing a threat to human health.

High nitrate concentrations in drinking water are especially dangerous. For example, in some semiarid areas like Botswana, cattle have died after consuming groundwater with nitrate values above 200 mg/l. Already at much lower levels nitrates can be fatal to nursing infants.

With efficient fertilisation health risks and environmental pollution can be reduced. Here, the term “efficient nitrogen fertilisation” refers to the ideal situation from the farmers’ point of view, in which the crop receives neither too little nor too much nitrogen.

This guideline has been designed for farmers and agricultural professionals as a handbook of information on nitrogen fertilisation in agriculture in the Arab region. It presents tools and methods that can be used to evaluate the nitrogen status of soil and plants and that allow the calculation of fertilizer requirement for different crops within the Arab region.

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