Sustainable irrigation reduces arsenic bioavailability in fluvio-alluvial soils promoting microbial responses, high rice productivity and economic profit

Abstract

Minimizing arsenic (74.92As33) loading into rice plants, we suggest adopting alternating wetting and drying (AWD) irrigation as a sustainable water management strategy allowing greater silicon (28.08Si14) availability. This two-year field-based project is the first report on AWD's impact on As-Si distribution in fluvio-alluvial soils of the entire Ganga valley (24 study sites divided into six Gangetic divisions), seasonal variance (pre-monsoon and monsoon), rice plant anatomy and productivity, soil microbial diversity, microbial gene ontology profiling, and cellular metabolic pathways. Under AWD to flooded and pre-monsoon to monsoon cultivations, respectively, As bioavailability was reduced by 8.71–9.25% and 25.68–26.13%. In the pre-monsoon and monsoon seasons, the rice grain yield under AWD improved by 8.41% and 9.96%, respectively proving the economic profitability. Compared to waterlogging, AWD proves to be the optimal soil condition for supporting soil microbial communities in rice fields, allowing diverse metabolic activities, As-resistance, and active expression of As-responsive genes and gene products. Finally, it is determined that by using AWD, the use of groundwater can be reduced, lowering the cost of pumping and field management and generating an economic profit for farmers. These combined assessments prove the acceptability of AWD for the establishment of multiple sustainable development goals (SDGs).