Depth-wise distribution of soil carbon and nitrogen under custard apple (Annona squamosa L.) based Agri-horticulture system

Abstract

An experiment was conducted at All India Co-ordinated Research Project for Dryland Agriculture, Gandhi Krishi Vignana Kendra, Bangalore during kharif 2017 to assess the effect of custard apple (CA) based agri-horticulture system on distribution of carbon and nitrogen in soil at different depths. The experiment consisted of 15 treatments viz., T1:CA+Finger millet, T2:CA+Fodder maize, T3:CA+Field bean, T4:CA+Niger, T5:CA+Chilli, T6:CA+Cowpea, T7:CA+Foxtail millet, T8: Finger millet alone, T9: Fodder maize alone, T10: Field bean alone, T11: Niger alone, T12:Chilli alone, T13: Cowpea alone, T14: Foxtail millet alone and T15: Custard apple alone, replicated thrice using randomised block design.The results of the investigation revealed that carbon and nitrogen at different depths varied significantly among different treatments under custard apple based agri-horticulture system. At 0-15, 15-30, 30-60 and 60-90 cm depth of soil, the organic carbon (6.11, 5.77, 4.15 and 3.12 g kg-1, respectively) and total carbon (6.74, 6.72, 5.40 and 4.49 g kg-1, respectively) were found higher under CA+Cowpea intercropping system. Lower values of organic carbon (4.42, 4.01, 2.73 and 1.94 g kg-1, respectively) and total carbon (5.34, 5.36, 4.14 and 3.50 g kg-1, respectively) were recorded in Fodder maize alone system. Higher inorganic carbon content at 0-15, 15-30, 30-60 and 60-90 cm depth of soil was recorded under Fodder maize alone (0.92, 1.35, 1.41 and 1.56 g kg-1, respectively) treatment and lower values were recorded in CA+Cowpea (0.63, 0.95, 1.25 and 1.37 g kg-1, respectively) intercropping system. At 0-15, 15-30, 30-60 and 60-90 cm depth of soil, higher available nitrogen (105.31, 91.33, 70.13 and 50.09 mg kg–1, respectively) and total nitrogen (636.65, 581.63, 515.37 and 393.65 mg kg–1, respectively) were recorded under CA+Cowpea intercropping system and lower values were under Fodder maize alone treatment.