Acacia nilotica tree/wheat Interaction: Effect of Irrigation and Fertilizer in a Traditional Agroforestry System in central India

Abstract

Effect of Acacia nilotica tree on growth and productivity of wheat crop (Triticum aestivum L.) was evaluated under irrigated and non-irrigated condition. Nitrogen fertilization was made in irrigated condition. Light intensity was reduced maximum 60% at 2 m from the tree trunk and declined with the distance. Density, aboveground biomass, yield and harvest index ranged across the distance, from 368 to 1187 tiller m^-2, 200 to 507 gm^-2, 429 to 1078 gm^-2 and 0.43 to 0.46, respectively in irrigated condition and 184 to 282 tiller m^-2, 86 to 145 gm^-2, 168 to 295 gm^-2 and 0.40 to 0.42, respectively in non-irrigated condition. Yield declined maximum 52% under the tree canopy in irrigated condition and minimum 33% in non-irrigated condition. Beyond the tree canopy, reduction in the yield was 8% greater in irrigated than that in non-irrigated condition. However, yield under the tree canopy was 3 times greater in irrigated condition than that in non-irrigated condition. Soil organic C and total N were 35% and 13%, respectively greater in irrigated and 43% and 46%, respectively greater in non- irrigated condition compared to open field. Soil organic C under the tree canopy under irrigated condition did not differ from that in non-irrigated condition. However, total N in soil under the tree was 2 times greater in irrigated than that in non-irrigated condition. Soil organic C and total N being maximum at 2 m from the tree declined with the distance. On the contrary, C/N ratio at all the distance was lower in irrigated than that in non-irrigated condition.