Soil fertility evaluation: a potential tool for predicting fertilizer requirement for crops in Nigeria

In most developing countries including Nigeria, fertilizers are applied to the soil by uneducated farmers without particularly making reference to the specific need of the plant or soil. Therefore, intended efficiency/replenishment is not maximized and fertilizer use is not rationalized. This paper critically reviews the three basic approaches to soil fertility evaluation: Visual symptoms of nutrient deficiency, Plant tissue analysis and soil testing. The implications of these methods are examined in terms of predicting fertilizer requirements for crops in Nigeria. Furthermore, the paper discusses the methods of Soil fertility evaluation available. Focus is then shifted primarily to the soil testing method, describing in detail the main objectives behind carrying out soil testing, including the proper soil sampling tools, sound sampling techniques and handling of the samples.