Nutrient dynamics during the first three years of an alleycropping agroecosystem in southern USA

An alleycropping system (AC), usingAlbizia julibrissin as the tree species, was compared to an annual legume-based cropping system (NA) over a three-year period. In both AC and NA, a crop rotation was implemented with the following sequence:Mucuna deering iana, Trifolium incarnatum, Sorghum bicolor, Triticale aestivum, andSorghum bicolor. Aboveground biomass of crops was analyzed for C, N, P, K, Ca, and Mg. A soil fractionation method was used to determine P dynamics in different treatments through time. Aboveground net primary productivity (NPP) was higher in the AC than in the NA. Nutrient input-output balance of N, P, K, Ca, and Mg from January through November 1991 was higher for AC than for NA. Area-based sorghum yield in 1991 was lower in AC than in NA. comparative sorghum yield in 1991 at 1 m distance from the hedgerow was lower than NA sorghum. In a three year period, the alleycropping system seemed to be more efficient in tapping unavailable forms of soil P, and achieved a higher P stock than the annual legume-based cropping system.