Leucaena - wheat Alley Cropping: Relative Impact of Aboveground and Belowground Competition under Different Fertilizer Conditions

Abstract

Impact of aboveground and belowground competition on growth and productivity of wheat crop was evaluated under fertilized and non-fertilized conditions in a Leucaena leucocephala (Lam) De Wit based alley cropping system in sub-humid climate of India. To examine the impact of aboveground and belowground competition, three competition situations were created in both fertilizer and no fertilizer condition: crop + L. shrub neighbour, crop + L. hedge neighbour and sole crop treatment. Size (width) of the alley was Bm. Photosynthetic active radiation (PAR) was reduced 48% under shrub neighbour. However, PAR in crop + hedge neighbour treatment did not differ from that in sole crop treatment (open area). Grain yield of wheat crop was 24% lower in crop + hedge and 42% lower in crop + shrub neighbour treatment compared to sole crop. Fertilization increased yield of the crop 1.65 times under hedge and 1.64% under shrub neighbour. Similarly relative growth rate of the crop was increased 5% under hedge neighbour as well as shrub neighbour due to nitrogen fertilization. Nitrogen uptake and photosynthetic rate was 1.39 times and 1.72 times, respectively greater under Leucaena shrub in fertilizer compared to no fertilizer condition. Root / shoot ratio of wheat crop declined 12% under Leuceene shrub neighbour under fertilizer condition. Soil organic C in crop + shrub neighbour treatment being equal to that in crop + hedge neighbour treatment and was 8.7 % greater compared to sole crop plot, however, C / N ratio declined. Growth in Leucaena shrub was 19% and N uptake 3.4 times greater compared to the wheat crop.