Five years integrated crop management in direct seeded rice–zero till wheat rotation of north-western India: Effects on soil carbon dynamics, crop yields, water productivity and economic profitability

Different integrated crop management (ICM) modules have been developed to enhance the productivity and profitability of the rice-wheat rotation (RWR) of the upper Indo-Gangetic Plains (IGPs). As the available options are used quite often singly or with the few combinations, hence in the present study, eight ICM modules have been evaluated; wherein, ICM1&2- conventional transplanted rice fb flatbed wheat, ICM3&4- conventional direct seeded rice (DSR) fb furrow irrigated raised bed wheat without residues, ICM5&6- conservation agriculture (CA)-based modules [zero tilled (ZT) DSR and ZT wheat] with the wheat and rice residues, and ICM7&8- CA-based modules (ZTDSR and ZT wheat) with the wheat, mungbean and rice residues. Results revealed that ICM8 produced the highest mean rice grain yield, which was statistically similar to ICM1&7, however it was 10.1–20.7% greater than the ICM2–6 modules. Similarly, the ICM7 recorded 14–16% greater wheat grain yield than the ICM1–6 (five years' mean), but it was at par to the ICM8. Furthermore, the ICM7&8 produced 10–13% (5 years av.) higher system yields in terms of rice equivalents over the ICM1&2. Water use (WU) was the highest in ICM1&2 and was 8–12% higher than the ICM3–8. In contrast, the highest water productivity (WP) was recorded with the ICM7&8, wherein it was14–16% greater than the ICM1&2. The ICM1&2 had incurred the highest variable production costs (US$ 912–1105 ha−1 yr−1), followed by ICM7&8 (US$ 856–1021 ha−1 yr−1). Nevertheless, on an average, the ICM7&8 gave 19–22% additional returns than the ICM1&2. Also, the ICM modules had a significant (p < 0.05) and positive impact on the soil carbon (0.0–0.45 m). The CA-based (ICM5–8) residue retained modules registered a 10–25% greater total OC stock than the ICM1–4 in 0.0–0.45 m soil layer. The current study thus up-holds the importance of adequate inputs integration, and hence, adoption of the CA-based ICM in the RWR improved the soil carbon dynamics, crop yields, farm profits, besides water savings of the upper Indo-Gangetic Plains (IGPs) of north-west India.