INFLUENCE OF ORGANIC MATTER ON THE PHYSICAL QUALITY OF SOILS UNDER INTENSIVE AGRICULTURAL MANAGEMENT

Abstract

Intensive agricultural management causes soil alteration, which leads to a decrease in some of its physical characteristics and a change in its quality and fertility. Bulk density and hydraulic conductivity are parameters used to evaluate these effects on food production. Other factors, such as soil organic matter, are also relevant for assessing soil quality, including physical quality, due to their close relationship with other soil properties. The objective of this study was to evaluate the physical quality of soils subjected to frequent changes resulting from intensive agricultural management. Five soils (S1, S2, S3, S4, and S5) classified as Vertisols from Acámbaro, in the state of Guanajuato, Mexico, were evaluated. Sampling was carried out at a depth of 0 to 20 cm to obtain a homogeneous composite sample. Nineteen physical variables and the soil organic matter content were determined. A principal component analysis was applied to rank the most important variables and calculate physical quality indices. Soil S4 had a low degradation index, associated with particle stability and high hydraulic conductivity (7.0 cm h-1). Soils S1, S2, S3, and S5 were classified as having a moderate degradation index, attributable to intense mechanical effects such as subsoiling and harrowing. When the organic matter variable was integrated into the generation of the indices, the physical quality of all soils was considered high, and the degradation index decreased as a result of the high organic matter content (5.85–8.58 %) and reserves, which favor adequate physical conditions. The addition of labile organic materials, such as manure and compost, in intensive agriculture improves the physical quality of the soil over prolonged periods, with positive effects on its conservation.