|Mineral Fertilizer Use and the Environment (IFA - UNEP, 1998, 52 p.)|
|9. Nutrient losses and efficiency|
The need for rational and sustainable land use, especially in regions subject to severe population pressures, emphasizes the need for effective land use planning. The classification of land types according to their agricultural suitability, together with the implementation of soil conservation measures, was used with great success to combat the erosion and desertification problems encountered in US agriculture in the 1930s.
Fertilizer recommendations should take into consideration specific agro-climatic and environmental conditions. General recommendations need to be adjusted to the conditions of the particular field. They depend on factors such as soil characteristics, cultivation practices, quality and quantity of irrigation water, ground water table, crop rotations and the managerial capacity of the farmer. The expected yield level of a crop is an important consideration.
The rapid progress in information technology during the past decade, including Geographic Information Systems (GIS) and computerized mapping, offers the possibility of agro-ecological zoning which can help in a preliminary selection of crops and technologies, including appropriate fertilizer use, suited to the local conditions and the problems encountered.
In highly developed systems, precision farming may use satellite communication and detailed field and crop information to improve farm operations and nutrient efficiency by means of the site-specific application of fertilizers. Soil analysis and crop deficiency diagnosis to facilitate the fine-tuning of fertilizer rates to actual crop requirements are of fundamental importance to precision agriculture.
Precision agriculture does not, of course, necessarily require sophisticated machinery and satellite-positioning systems. Farmers in developing countries could well improve the precision of their plant nutrient programmes given soil testing facilities and sound advice.