Effect on Productivity in Rainfall Dependent Competition between Vigna radiata and Hardwickia binata in Arid Zone Agroforestry

A 9-year-old Hardwickia binata Roxb. Plants at a spacing of 5m × 5m was intercropped with V. radiata (L.) Wilczek in 2003 to study interactive effects of trees on resource use and crop production. Tree height, collar diameter and crown diameter did not differ (P < 0.05) between the treatments. Soil water content (SWC) was highest (P < 0.01) in August and lowest in December, 2003 depending upon rainfall. SWC was highest (P < 0.05) in AC plots and reduced in FC/ RC plots by 37.1%, 25.9% and 20.2% in August, September and December, 2003, respectively resulted from tree. Lowest SWC in 0-25 cm soil layer and at 1 m from tree suggested competitive use of soil water by the trees reducing crop yield (by 97%). Despite an increase in leaf water content, reduction in grain was relatively greater than husk and holm. Soil organic matter, P0₄-P, NO3-N and NH₄-N did not differ among the treatments and distances but these nutrients were highest (P < 0.01) in 0-25 soil layers suggesting trees role in nutrient enrichment.