Effect of zero tillage and residue retention on soil properties and wheat yield in rice-wheat system

Abstract:

A practical dilemma faces every rice-wheat farmer after the rice harvest: plough the stubble under and risk losing moisture to evaporation before wheat sowing, or leave the residue and risk poor seed-soil contact that compromises germination. This research evaluated four tillage-residue combinations, Conventional Tillage (CT), Zero Tillage (ZT), zero tillage with low residue retention (ZT+RL, 3 t/ha), and zero tillage with high residue retention (ZT+RH, 6 t/ha), on soil physical and chemical properties and wheat yield over three years (2020-2023) at the Southern Tablelands University of Agriculture, Canberra, ACT. A RCBD with four replications was used. After three years, ZT+RH raised soil organic carbon from 1.12% to 1.48%, reduced bulk density to 1.21 g/cc (CT: 1.38), and increased water-stable aggregates by 34% over CT. Wheat yield under ZT+RH reached 4.47 t/ha versus 3.42 t/ha under CT, a 30.7% increase. The labile carbon fraction was 68% higher under ZT+RH than CT. These results confirm that zero tillage with full residue retention can improve both soil quality and wheat productivity in temperate rice-wheat systems.