Near-saturated soil hydraulic conductivity and pore characteristics as influenced by conventional and conservation tillage practices in North-West Himalayan region, India

Tillage plays an important role in modifying soil hydraulic properties. The objective of the present study was to evaluate the effect of conservation tillage practices in a maize-wheat cropping system on nearsaturated soil hydraulic properties and pore characteristics in the North-West Himalayan region, India. Three treatments viz. conventional tillage (CT), minimum tillage (MT), and zero tillage (ZT) were evaluated in terms of field saturated hydraulic conductivity (ks), unsaturated hydraulic conductivity k(h), the inverse of capillary length (a), flow-weighted mean pore radius (r0), numbers of pores per square meter (n0) and water-conducting macroporosity (Ɛ). The above hydraulic conductivity and pore characteristics were derived from steady-state water flux (q) measured using hood infiltrometer at 0, -1, and -3 cm pressure head for each treatment after seven years of establishment of this tillage experiment. Results revealed significantly (p < 0.05) higher values of ks, k(h), a, and Ɛ in ZT as compared with CT. MT had intermediate values. Higher a values suggested a greater gravity-dominated flow under ZT and MT as compared with CT. Analysis of r0 values indicated better connectivity of pores in ZT and MT as compared with CT. Macropore flow suggested that on average pore radii, > 0.50 mm conducted about 63.60, 68.01, and 75.97 % of total flow (at 0 cm pressure head) in the corresponding water-conducting macroporosity of 0.00030, 0.00044, and 0.00069 % of soil volume under CT, MT, and ZT, respectively. Overall, zero-tillage based agriculture system was found to improve near-saturated soil hydraulic properties.