Impact of rainfall variability on major crops using the deficient rainfall impact parameter (DRIP): A case study over Karnataka, India

Understanding the aberrant weather and farmers' behavior under those is crucial for achieving climate resilience. Among weather parameters, rainfall significantly affects crop production, from pre-sowing decisions to harvesting. However, the existing indices often overlook farmers' decision-making. To address this gap, a new deficient rainfall impact parameter (DRIP) index was utilized to evaluate rainfall variability's effects on principal rainfed crops in Karnataka, India's second-largest dryland agriculture state. Datasets from 2011 to 2022 on area, production, and productivity of major crops of Karnataka were analyzed. Notably, the state's highest DRIP score was recorded in Kharif sorghum during 2016 and 2019 (12.8 and 8.6), indicating an impact of deficient rainfall on its production. Similarly, a higher reduction in the area under rabi sorghum was observed in 2016 with higher DRIP scores (10.9). Conversely, a meager decrease in the area under rainfed rice was observed in 2018 (1.6) and 2016 (1.2) even though there was a deficit of rainfall. In contrast, maize evaded drought impact during 2015–18 with negative DRIP scores, indicating crop shifts. However, finger millet suffered moisture stress in 2016 and 2018. Rabi wheat showed higher DRIP scores in 2016, 2017, and 2018 (12.2, 2.2, and 19.0) due to rainfall deficits. Similarly, the positive DRIP scores for pigeonpea in 2016–2018 signified decreased cultivation due to rainfall deficits. Chickpea, mainly cultivated in vertisols, showed marginal impact from rainfall deficits, except in 2016 and 2021. Groundnut had positive DRIP scores in 2017–2018 (1.1 and 0.5) due to deficit rainfall and in 2020–2021 (1.7 and 0.5) due to crop replacement with onion. Castor, on the other hand, exhibited positive DRIP scores in most years, except 2019, 2020, and 2022. This study underscores the importance of understanding rainfall variability and its implications for agricultural practices, thereby contributing to informed decision-making and strategic planning to ensure regional and national food security.