Shade effects on moisture relations of agroforestry systems

Abstract

Although competition of shade trees for water with shaded crops has been a major argument in favor of the removal of shade trees in agroforestry systems, experimental results do not always confirm that shade trees increase water consumption and reduce soil moisture. Soil moisture was shown to be much higher under coffee shaded with the dense canopied Erythrina poeppigiana (Walp.) O.F. Cook than the more open canopied Eucalyptus deglupta Blume. Soil moisture decreased with increasing distance from trees when Gliricidium sepium (Jacq.) Steud. or E. poeppigiana were associated with Phaseolus vulgaris L. Increased competition for moisture when crops are associated with shade trees can often be offset by reduced evaporation at the soil surface due to reduced soil temperatures under shading.