Strategies for the management of soil acidity

Abstract

Whereas previously farmers have had the option of abandoning their land temporarily or permanently, increasing population pressure now dictates that farmers must manage soil acidity in order to maintain productivity and their livelihood. Here we examine the management options available to farmers, from the wealthy to the subsistence farmer and identify those that are effective for the different types of farmers in different environments. We also consider the strategies that apply when governments and other land users intervene in land use matters. The paper draws partly on the authors' experience and on the wealth of previously published information from around the world. It endeavours to steer a course between fundamental soil/crop science and socio-economic considerations, although it cannot be divorced from either. Techniques considered range from those that, to a degree, avoid the problem (alternative land use, alternative crop plants), to those which treat the problem (correcting the soil via inputs of organic materials, lime, mineral fertilisers, etc.). Techniques that aim at modifying the plant or the soil should rely on correct diagnosis of the major limitations since yields on different acid soils are low for different reasons. Converting such techniques into successful strategies must consider external factors. That is, alternative plants must depend on availability of markets; soil inputs must depend either on a local source of the inputs and/or sufficient cash flow in order that they be feasible. Other feasibility issues include whether subsoil acidity can be managed, whether the level of management required is compatible with the farming system practiced, or whether the acidity management is short-term or sustainable over a longer period. We conclude that it is technically feasible to make acid soils productive. However, successful implementation depends on integration of technical factors with social and economic factors, that is, on the development of suitable strategies.