In order to achieve high levels of agricultural productivity in the tropics at the lowest possible economic and ecological costs, we need to properly understand the relationship between nutrients in the soil and crop productivity. For this to happen, the current understanding needs to change. The conventional view of the relationship between soil nutrients and crop productivity in the tropics is leading to both damaging agricultural policies and inefficient and damaging farm-level practices. There is no need to use the huge quantities of chemical fertilizers that are so often recommended. In fact, often times the use of such fertilizers is unnecessary, expensive and harmful to the environment, especially because farmers often stop using organic matter when they use chemical fertilizers.
Much of the theory described here was originally developed by Drs. Artur and Ana Primavesi. For a much more in-depth analysis of the chemical and biological issues described in this article, the best book at present is Ana Primavesi’s The Ecological Management of the Soil (available in Spanish and Portuguese). This article will discuss the conventional concept of soil fertility and some of its shortcomings; a new conception of soil fertility; and how the new theory can be put into practice.