RESOURCE CAPTURE AND UTILIZATION IN INTERCROPPING - WATER

The capture and utilization of water by sole and intercrops are compared by decomposing crop production/unit area into uptake/unit area (capture) and production/unit uptake (utilization efficiency). Data are from published studies. Comparisons are made by contrasting data from the intercrops against weighted means from the sole crops, with weights based on the proportion of each species in the intercrop. Water capture by intercrops differs from water capture by sole crops only slightly (usually between - 6 and + 7%). Water-utilization efficiency by intercrops, however, greatly exceeds water-utilization efficiency by sole crops, often by more than 18% and by as much as 99%. Four mechanisms that may account for the consistent increases in water-utilization efficiency by intercrops are postulated on the basis of crop water relations theory but empirical data from intercropping studies are not adequate to test them. The water-utilization efficiency response by intercrops to increased levels of seasonably available water differs from the response by sole crops. Variation in plant density often affects water-utilization efficiency.