Intercropping sorghum with nitrogen fixing trees in semiarid India

The influence of three nitrogen fixing tree (NFT) species viz., Faidherbia albida, Acacia ferruginea, Albizia lebbeck and four nitrogen levels (0, 20, 40 and 60 kg N ha−1) on intercropped rainfed sorghum was investigated at Hyderabad, India. The trees were established in shallow alfisols during 1985 with a spacing of 4 × 4 m. Intercropping was done in 1993 and 1994. The effect of trees on radiation interception, soil moisture, crop growth, yield components and yield of sorghum was examined. Association of tree species reduced grain and dryfodder yields of sorghum to an extent of 12 to 40% compared to sole crop situation. The reduction was maximum under A. lebbeck, minimum with F. albida and moderate under A. ferruginea. Application of 40 kg N ha−1 resulted in increased grain and dryfodder yields over other levels. Crop growth in terms of LAI and drymatter had similar response. The receipt of photosynthetically active radiation (PAR) was low under NFTs compared to open situation. The relative PAR intercepted under the trees was in the order: F. albida > A. ferruginea > A. lebbeck. Soil moisture status was more favourable under F. albida than under the other tree species. Soil moisture at all stages of crop growth was more in sole crop situation.