Surface crusting as a constraint to sustainable management on a tropical alfisol: I. Soil physical properties

Abstract

Surface sealing and crusting on alfisols in the semi-arid tropics pose serious limitations to sustainable crop production and environmental quality. This study was conducted to assess some physical properties related to crust formation on a clayey-skeletal, mixed, isohyperthermic Udic Rhodoustalf at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), India. A critical proportion (30 to 40%) of fine textural fractions, particularly silt, appeared to be important in structural crust formation due to aggregate breakdown, rainfall compaction, and particle rearrangement of the surface soil. Significantly higher water dispersible clay percentage (7.1%) and dispersion ratio (0.34) at 60 days after planting (DAP) indicated diminished structural stability and increased slaking tendency of surface aggregates. Infiltration rates decreased by 40 to 60% in tilled bare systems from 0 to 60 DAP. Termite activity appeared to increase cumulative infiltration and steady state infiltration rate although additional research is required to determine the precise nature of its influence on porosity and pore continuity. Soil cover and biological components may be manageable factors to improve soil structure and stability, as well as, to reduce crusting and its associated adverse effects in the semi-arid tropics.

Soil cover and biological components may be manageable factors to improve soilstructure and stability, as well as, to reduce crusting and its associated adverse effects.