Evaluating chemical and physical quality indicators for a structurally fragile tropical soil

Abstract

AbstractIn tropical regions with well‐defined wet and dry seasons, repeated wetting and drying cycles can harden exposed soils and inhibit root growth. While this phenomenon has been well documented, the relationships between plant productivity and chemical and physical soil parameters have not been well defined. The current study identifies the abiotic parameters that best relate to measures of plant development, specifically to corn productivity. The primary goal of this research was to provide information to improve agricultural sustainability in humid tropical ecosystems. The effects of using plant residues as a cover on a sandy soil were studied. Four leguminous species were planted in an alley cropping system, Leucaena leucocephala, Cajanus cajan, Clitoria fairchildiana and Acacia mangium, and corn was planted in January 2007 between legume rows. We measured the most important chemical and physical soil parameters. Yield indicators included cob weight and the weight of 100 kernels. The application of plant residues altered soil conditions and increased rootable soil volume. This change was associated with an increase by 10% in water retention above field capacity in the uppermost soil layer of the residue‐covered sections of the experiment. In the control sections cobs were up to three times lighter (31.43–93.38 g) in the bare soil control than those from residue‐covered sections of the experiment. Dynamic indicators related to nutrient absorption and crop evapotranspiration, such as the number of days with water stress and rootable soil volume, were the most suitable indicators for assessing soil quality. The response of corn was best related to complex physical indicators, including the amount of N applied via legume residues.