Size and Stability of Soil Aggregates and Organic Matter Content in Soilwith Rice Straw Management in Rice-Sunflower Cropping System

Residue management plays a crucial role in enhancing soil organic carbon stabilization by promoting soil aggregation. The current study examined the impact of various residue management practices on soil physico-chemical properties and formation of different sizes aggregates in rice-sunflower cropping system on sandy clay loam soil at Agricultural Research Station, Tornala, Siddipet district, Telangana state during rabi 2022-23 and 2023-24. Compared to residue burning or removal, residue retention followed by zero till Sunflower resulted in an increase in water-stable large macro aggregates, mean weight diameter (MWD), and geometric mean diameter (GMD) by 41.70%, 35.10%, and 17.08% respectively. Residue incorporation treatments increased MWD and GMD by an average of 17.28% and 10.26%, respectively, over the residue-burning treatment. Residue retention followed by zero till Sunflower recorded the highest proportion of >4.75 mm (26.99%) and 4.75-2.00 mm (23.64%) size fractions and the lowest proportions of these fractions were recorded with residue burning with 14.37% and 15.15%, respectively. In contrast, the highest proportions of 2.00–0.5 mm (43.67%) and 0.5–0.25 mm (15.44%) size fractions were observed under residue burning, followed by residue removal + RDF which recorded 41.10% and 14.64%, respectively. Soil organic matter was significantly higher in treatments involving straw incorporation, particularly in those with residue incorporation as such + RDF (T 4 -8.20 g kg⁻¹) and C: P ratio adjustments (T 6 -8.10 g kg⁻¹).