In water scarce regions of South Asia, diversification of rice with maize is being advocated towards
sustainability of cereal-based cropping systems. Adoption of innovative agronomic management
practices, i.e., conservation agriculture (CA) and sub-surface drip irrigation (SSDI) are considered
as key strategies for much needed interventions to address the challenges of water scarcity under
projected climate change. Benefits from CA and SSDI concerning water economy are well-established,
however, information about their complementarity and water budgeting in cereal-based systems are
lacking. A field study was conducted with process-based model (HYDRUS-2D) to understand water
transport, root water uptake and components of soil water balance in maize grown in rotation with
wheat after five years of continuous adoption of conservation agriculture. In this study, altogether
eight treatments comprising of 6 CA+ treatments (CA coupled with SSDI); permanent beds using
sub-surface drip (PB-SSD) with (WR) and without (WOR) crop residue at different N rates, 0, 120 and
150 kg N ha−
1 were compared with CA (PB using furrow irrigation-FI with crop residue-120 kg N ha−
1)
and conventional tillage practices (CT) (CT using FI without crop residue-120 kg N ha−
1). Results
showed that the model could simulate the daily changes in profile soil water content with reasonable
accuracy in all the treatments. Simulated soil water balance indicated higher cumulative root water
uptake (CRWU), lower cumulative evaporation (CE) and higher soil water retention in CA+ (PB-SSD+
crop residue at 150 and 120 kg N ha−
1) than CA and CT plots. Hydrus-2D model efficiency > 0, RMSE
between 0.009–0.026 and R2
value between 0.80–0.92 at P < 0.01 indicates that the model is
performing efficiently. The mean evaporation from CA+ treatments was 10 and 36% less than CA and
CT treatments, respectively. On average, CRWU under CA+ treatments were 14–48% higher than FI
treatments. The mean cumulative deep drainage in CA+ plots was 80–100 mm less than CA and CT
plots. In CA+ based plots significantly higher biomass production and radiation use efficiency were
observed with reduced water use than CA and CT. Therefore, the study justifies the water-saving
nature of CA+, while maintaining higher productivity and meeting the transpiration demand of crops
and halting unnecessary evaporation and deep drainage losses.
