Conservation tillage (CT) for climate-smart sustainable intensification: Benchmarking CT to improve soil properties, water footprint and bulb yield productivity in onion cultivation

Environmental sustainability indicators for conservation tillage (CT) in agricultural systems primarily focus on assessing the impacts on soil organic carbon (SOC) and water footprint (WF). One way to improve these indicators is by boosting crop production while minimizing environmental impact through the implementation of sustainable intensification (SI) and climate-smart agriculture (CSA) to ensure food security. Conservation agriculture (CA) based CT practice with crop residue retention has potential for benchmarking the conserving of water in agriculture, improving soil health, crop productivity and ensuring agricultural sustainability. The CT-based water-saving potential in onion cultivation nonetheless remains understudied in Bangladesh. For this, a field experiment was undertaken to assess soil properties and water footprint in onion cultivation in the Charland agroecosystem in Jamalpur, Bangladesh. Three different tillage practices, such as minimum tillage (MT), tractor tillage (TT) and conventional power tillage (PT), and flatbed flood irrigation were introduced with four replications. Tillage practices showed significant positive effects on yield characteristics and bulb yields. The findings indicate that the MT practice in onion (BARI Piaz-4) cultivation resulted in the highest fresh bulb yield of 22.79 t ha^-1, followed by TT (20.48 t ha^-1) and PT (16.25 t ha^-1) practices. The MT practice achieved the highest water footprint (WF) savings of 40% water, where crop biomass, including above and below-ground parts, bulb size, yield characteristics, and yield productivity were significantly increased. The findings also indicate a direct correlation between the water productivity index (WPI), WF and the bulb yield under MT practice. The study's findings favor CT practice and, therefore, suggest a methodology of employing MT practice as a benchmark to increase agricultural water-saving potential. It can also be used as a reference for promoting water conservation practices achieving sustainable development and improving resource efficiency in agriculture.