Understanding the Impacts of Sowing Time and Tillage in Optimizing the Micro-Environment for Rainfed Lentil (Lens culinaris Medik) Production in the Lower Indo-Gangetic Plain

Abstract

Low productivity of rainfed lentil (Lens culinaris Medik) in the post-harvest rice fallows due to soil moisture stress is a major concern in the lower Indo-Gangetic plains. We hypothesized that adjusting sowing dates with proper tillage can optimize the microenvironment for rainfed lentil allowing higher seed yield and improving soil biology. A 2-year field experiment was laid out following a split-plot design during 2014–2016 integrating three lentil sowing dates (early, S1; mid, S2; and late, S3) with two tillage practices (zero tillage, ZT, and conventional tillage, CT) in an Inceptisol of West Bengal, India. The objective was to examine various physiological (relative leaf water content (RLWC), leaf area index (LAI)) and biochemical (chlorophyll, carbohydrate, free amino acids, phenol, proline) changes in lentil, soil biology (soil microbial biomass carbon (SMBC), dehydrogenase activity (DHA)), and lentil yield attributes (grain yield, seed index). When sown early, S1, lentils produced ~ 47% and 15% higher grain yield and ~ 23% and 18% higher seed index over S3 and S2, respectively. Delayed sowing (S3) induced early maturity, severe moisture stress that resulted in lower RLWC (14%), LAI (49%), chlorophyll (37%), and carbohydrate (33%) content compared to S1. SMBC and DHA were significantly higher at S1, specifically under ZT, but had negative correlation with phenol, amino acids, and proline. Our experiment concludes that early sowing of lentil coupled with zero tillage can mitigate soil moisture stress in the relay-cropped, rainfed lentil and provide an optimum microenvironment to facilitate sustainable production of lentil in the region. Graphical abstract