Nutrient and Litter Dynamics in Cowpea and Pongamia Agroforestry System

Abstract

Agroforestry systems offer sustainable solutions for enhancing soil fertility, improving crop productivity and maintaining ecological balance. Litter production and decomposition play a significant role in nutrient cycling and soil fertility enhancement within agroforestry systems. The study was conducted in the ‘M’ block of AICRP on Agroforestry unit, ZARS, UAS, GKVK, Bangalore, during January 2022 to June 2022. This study investigates the nutrient recycling and litter dynamics in a cowpea (Vigna unguiculata) + Pongamia (Pongamia pinnata) agroforestry system under semi-arid conditions. Key parameters such as litterfall quantity, decomposition rate, nutrient release patterns and soil nutrient status were analyzed before crop sown and after harvest of the crop in cowpea + Pongamia agroforestry system. The results revealed that litterfall production followed unimodel pattern and a distinct peak was observed in February month in all the germplasms. RAK-2015-10 + cowpea, have recorded the highest accumulation of litterfall among the other germplasms in the month of February (187.85 kg ha-1) and the lowest litterfall production was noticed in June month (100.70 kg ha-1). Among the evaluated germplasms and intercrop interactions, RAK-2015-09 + cowpea combination exhibited the poorest performance, with the highest litterfall accumulation observed in February (157.30 kg ha-1) and the lowest in June (77.60 kg ha-1). The interaction between RAK-2015-10 germplasm and cowpea significantly enhanced nitrogen input through biological fixation, increasing from 265.52 kg ha⁻¹ before sowing to 278.18 kg ha⁻¹ after crop harvest through biological nitrogen fixation, while Pongamia contributed substantially to organic matter and macro-nutrient cycling via litterfall. Litter decomposition showed a steady nutrient release pattern, positively influencing soil fertility and supporting the growth of intercrops. The synergistic interaction between tree and legume components in the system demonstrated improved nutrient use efficiency and long-term sustainability. Expanding the cultivation of cowpea under RAK-2015-10 + cowpea germplasm can significantly improve the soil fertility and productivity under agroforestry system.