Evaluation of agroforestry tree species and irrigation methods in sodic soil

A field experiment was conducted during 1995-97 in sodic soil with four tree species viz., neem (Azadirachta indica. A.Juss). pungam (Pongamia glabra. L), casuarina (Casuarina eqisetifolia. JR and G. Forst) and subabal (Leucaena leucocephala. Lamk) in main plots and the irrigation methods, viz., drip, pitcher and surface basin in sub-plots. The intercrops viz., sorghum and sunflower were grown as rainfed and ploughed in situ. Among the four tree species subabul had recorded the highest mean growth rate in terms of collar diameter (17.43 cm) and the maximum biomass yield (4.840 kg/tree/year) followed by neem with the collar diameter 16.30 cm and the biomass 3.756 kg/tree/year. Among the irrigation methods drip irrigation had recorded the highest mean collar diameter (15.57 cm) and the biomass yield (3.971 kg/tree/ year) followed by the surface basin with collar diameter 15.52 cm and biomass yield 3.913 kg/tree/year. The pitcher method of irrigation had recorded the lowest collar diameter (14.72 cm) and the biomass yield of 2.812 kg/tree/year. Annually about 1460, 2431 and 3650 litres of water were applied through drip, pitcher and surface basin respectively. Water saving by drip over surface basin is 60% and 39.9% over pitcher method. Irrigation methods invariably reduced the sodic soil properties viz., pH, EC (dsm), and sodium absorption ratio significantly over a period of two years.