Temporal variation of saturated and near‐saturated soil hydraulic conductivity and water‐conducting macroporosity in a maize‐wheat rotation under conventional and conservation tillage practices

Knowledge of temporal variation of soil hydraulic properties (SHPs) is crucial to understand soil physical behaviour under different tillage practices. The objective of this study was to assess the variation of saturated and near-saturated soil hydraulic conductivity (NSHC) and water-conducting macroporosity (sigma) under long-term (09 years) tillage regimes viz. zero tillage (ZT), conventional tillage (CT), and minimum tillage (MT) in a rain-fed maize-wheat crop rotation (RMWC) in the North-West Himalayas, India (NWHI). A hood infiltrometer (HI) was used to measure the steady-state water flux (q) at 0, -10, and -30 mm pressure head (PH) after harvesting of maize and over two wheat cropping seasons for each treatment. The infiltration data were analyzed in terms of unsaturated hydraulic conductivity k(h), field saturated hydraulic conductivity (k(s)), water-conducting macroporosity (sigma). The results showed that the seasonal effects on k(s), k(h), and sigma values were significantly different (p <= 0.05) for tilled treatments (CT and MT). In contrast, no significant difference (p <= 0.05) was found for untilled treatment (ZT). Significantly higher (p <= 0.05) k(s), k(h), and sigma values were observed in ZT than CT and MT, associated with higher SOC and lower rho(b) values. A multivariate analysis of variance of the k(s) showed a highly significant difference (p <= 0.01) with both time and tillage treatments. Overall, a significant improvement of hydraulic conductivity characteristics was observed during the wheat-growing seasons compared with the maize harvest season. The temporal dynamics of SHPs under different tillage regimes indicate that ZT can be a suitable tillage practice for reducing runoff and soil loss in monsoon maize and winter wheat cropping system.