Soil erosion and nutrient losses in seasonal tropical agroecosystems under various management techniques.
Soil erosion losses and erosion control techniques in agroecosystems on the Pacific coast of Jalisco, Mexico were studied for 2 years under 7 management treatments: undisturbed forest (control); maize; maize with forest litter as a protective mulch; Panicum maximum; Cenchrus ciliaris; and 3m and 10 m wide anti-erosion grass strips below the maize fields. Plots were 20-40 m2 with an av. slope of 22.5°. All but forest plots were burned after being cleared. Most of the nutrients lost were adsorbed on soil particles which were eroded from the plots by surface water flow. Soil erosion in the forest plots was <0.20 t/ha per year, but up to 130 t/ha per year in the maize and P. maximum treatments. The most successful treatment for reducing erosion was the use of a mulch placed on maize fields. This reduced erosion by >90% and increased crop productivity by almost 30%. The use of anti-erosion grass strips did not reduce erosion significantly over the experimental period, but might if a longer time were allowed for their development.