Tillage and Crop Rotation Effects on Mechanical Properties and Structural Stability of a Sandy Loam Soil in a Semi-arid Environment

Tillage has strong influence on soil architecture and thus modifies soil matrix-pore system. Short-term (7 years) changes in soil mechanical properties (macro-and micro-level) were evaluated in pigeon pea-wheat (P-W), cotton-wheat (C-W) and maize-wheat (M-W) cropping systems (CS). Tillage systems were: no tillage (NT) and conventional tillage (CT) with or without crop residue retention (+R/-R). Soil bulk density didn't change appreciably. Soil resistance to penetration at 10–20 cm layer reduced under NT system with residue retention (NT+R), owing to greater soil water content. Maintaining residue, irrespective of tillage, improved soil aggregation and bulk soil organic carbon content (total, particulate and KMnO₄-oxidizable C), promoting a better root-zone hydro-physical regime in all CS. Effect of tillage on water-stability of aggregates was observed at 0–7.5 cm layer only, in air-dried, compared to field-moist samples. The tillage-CS interactions had impact on mean weight diameter (MWD) of air-dried aggregates at 0–7.5 cm layer. The MWD was higher in NT+R under P-W than any other tillage/residue-CS combination. Residue incorporation in CT also resulted in greater macro-aggregates (>0.25 mm), and thereby larger MWD. Disruption of aggregates through different energy inputs was the least under NT+R, indicating predominantly higher amount of water-stable aggregates, providing a better soil structure.