Soil moisture dynamics, rooting traits, crop and water productivity of wheat under different tillage, irrigation and nutrition conditions

Water scarcity coupled with reduced nutrient-use efficiency (NUE) is challenging the sustainability of wheat production in the North-Western Plains of India. Suitable soil tillage practices, water, and nutrient management are thus essential to harvest high wheat yields on a long-term basis. Thus, a fixed-plot experiment was set and continued for three years to assess the main and interaction effects of tillage, irrigation, and fertilizers on water- use efficiency (WUE) and wheat yield. Zero-till flat bed (ZTFB) and conventional till-raised bed (CTRB) condensed the irrigation water requirement by 1163-1218 m3 ha-1 and 698-762 m3 ha-1, respectively, compared to conventional till-flat bed (CTFB) without affecting wheat yields during 2016-2019. Apart from the saving in irrigation water, CTRB enhanced grain turn over by 8.12-31.5%, biomass by 3.47-34.1%, WUE by 27.0-30.9% and irrigation water productivity (IWP) by 55.2-57.5% over CTFB. Likewise, CTRB recorded a 4.4-10.1% greater photosynthetically active radiation (PAR) interception over CTFB and ZTFB during the study years. ZTFB had the highest moisture level (11.2%-22.5%) for 0-0.3 m soil layer. Applying irrigation at 25% depletion of available soil moisture (DASM) and 100% recommended rates of nutrients (RRN) resulted in significantly greater grain and biomass yields and WUE over the lower levels of irrigation and nutrients during 2016-2019. Further, the treatment combination of CTRB or ZTFB + 25% DASM + 100% RRN was more productive, registering significant enhancements in grain and biomass yields, and WUE compared to CTFB with all other fertilizer and irrigation levels. The study concludes that 25% DASM with 100% RRN application under CTRB and ZTFB in wheat are synergic to attain higher crop and water productivity against individual application of these agronomic variables.