Physical characteristics of soil under different cropping and natural system on the plain of jars, Xieng Khouang province, Laos

Abstract

Conservation agriculture and direct seeding mulch-based cropping (DMC) systems greatly modify plant and soil interaction. Plants commonly provide energy that fuels biological processes and either directly or indirectly creates structure within soils. Under DMC systems 7 large biomass is produced both above and below ground, thereby influencing soil parameters. Different methods can be used to measure soil characteristics, but simple and cheap tools for on-site recording are not common. This study attempts to analyse the physical soil parameters (water-stable aggregate, bulk density and soil permeability) of various ecosystems: savannah grassland, pine forest, ploughed upland rice fields, and improved Brachiaria ruziziensis and Stylosanthes guianensis pasture lands. The results show that these forage species have a clear effect on soil structure: medium soil particles (<0.250mm) are fixed into water-stable aggregates, bulk density decreases, and as a result soil permeability is modified. The continued recording of such data over time will enable evaluation of the iterative and cumulative biological effects (organic content, root density, particle arrangement) of fodder species and cropping systems on soil characteristics. (Résumé d'auteur