Soil Resource Conservation Technologies on Rainfed Mung bean Root Growth and Their Potential Root Carbon Additions under Variable Rainfall Situations in Semi-Arid Agroecosystem

Resource conservation technologies (RCTs) are recommended to address the rainfall deficits of dryland crops in semi-arid regions. Understanding the effects of RCTs on mung bean (Vigna radiata L. Wilczek) plant roots and thereby yields is crucial for drought tolerance, and few studies are reported regarding this. A field study was conducted during 2015 and 2016 at Indian Council of Agricultural Research - Central Research Institute for Dryland Agriculture (ICAR-CRIDA), India to evaluate root dynamics of Drought Tolerant (DTV) and Drought Susceptible (DSV) varieties of mung bean under Organic Amendment at the rate of 3 t ha^-1 (OA), resource conservation measure (in-situ Conservation Furrow for every three rows of the crop) as RCM, the combination RCM + OA under normal and deficit rainfall conditions. An innovative field root architectural sampling was followed to extract roots from different soil depths with minimal root losses. RCM increased the rooting depth by 5 cm while OA increased root length density (RLD). Together these measures improved root plasticity as early increased root length, high RLD at deeper soil depths (≥ 0.5 cm cm^− 3), and fine roots of < 1.08 mm diameter in the drought-tolerant mung bean cultivar. The estimated potential carbon additions of mung bean root to soil is 7.1–16.3 kg ha^− 1 for a single crop. Integration of both application of organic amendment and in-situ conservation furrow for every three mung bean rows to drought tolerant mung bean cultivar resulted in increased rooting depth (RD), RLD and more absorptive roots mitigated moisture stress through root adaptation under Semi-Arid Tropic (SAT) rainfed ecosystems. Soil carbon addition is the co-benefit associated with these RCTs.