During 2024-25, a field study was undertaken at the Cotton Research Unit of Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, to study the changes in carbon dynamics with crop residue mulching under Bt-cotton. The experiment was laid out in a Randomized Block Design (RBD) with four replications and five treatments. The treatments involved the application of different crop residue mulches along with the general recommended dose of fertilizers (GRDF). Treatments comprised: T
1 (GRDF), T
2 (GRDF + Mulching with wheat straw @ 50% of potential yield), T
3 (GRDF + Mulching with cotton straw @ 50% of potential yield), T
4 (GRDF + Mulching with soybean straw @ 75% of potential yield) and T
5 (GRDF + Mulching with weed biomass).
The treatment receiving GRDF + Mulching with soybean straw @ 75% of potential yield (T4) recorded significantly higher carbon fractions compared to other treatments. It registered the maximum very labile carbon and labile carbon, indicating a notable improvement in the active carbon pool, along with the highest total organic carbon. Significantly highest less labile carbon was also observed in GRDF + Mulching with soybean straw @ 75% of potential yield (T4), which was statistically at par with GRDF + Mulching with weed biomass (T5). For non-labile carbon, the highest value was recorded in GRDF + Mulching with cotton stalk @ 50% of potential yield (T3), whereas the lowest was observed under GRDF (T1) alone. In terms of water-soluble carbon, GRDF + Mulching with soybean straw @ 75% of potential yield (T4) recorded the highest value, which was statistically at par with GRDF + Mulching with weed biomass (T5) and GRDF + Mulching with wheat straw @ 50% of potential yield (T2), indicating considerable variation among treatments. Similarly, the highest potential mineralizable carbon was obtained in GRDF + Mulching with soybean straw @ 75% of potential yield (T4), which was statistically at par with GRDF + Mulching with weed biomass (T5) and GRDF + Mulching with wheat straw @ 50% of potential yield (T2).
