Development of an arable layer: A key concept for better management of infertile tropical savanna soils

Abstract

A concept that is highly relevant for the better management of infertile tropical savanna soils is that of the buildup of an “arable layer”. Before tropical savanna soils can be used for no-tillage systems, the soil’s quality in terms of physical, chemical and biological characteristics need to be improved. The application of this concept will depend on the prevailing soil constraints and current land use, for example, soil compaction and loss of soil structure versus a depletion of soil nutrients and the type of crops to be cultivated. The concept includes tillage practices to overcome physical constraints, an efficient use of amendments and fertilizers to correct chemical constraints and imbalances, and the use of improved tropical forage grasses, green manures and other organic matter inputs such as crop residues, to improve the soil’s “bio-structure” and biological activity. The use of deep-rooting plants in rotational systems to recover water and nutrients from subsoil is also envisaged in this scheme. This concept builds on earlier suggestions for the better management of tropical soils. To be functional, however, more attention needs to be given to the driving forces behind farmer decision-making process and the existing policies for intensifying agriculture on infertile savanna lands.