Crop productivity, soil health, and energy dynamics of Indian Himalayan intensified organic maize-based systems

The sustainability of prevailing maize-fallow system in rainfed ecosystems of the Eastern Himalayan region (EHR) of India is often questioned due to poor economic return and negative impact on soil health. Hence, the six cropping systems, maize-fallow (M-F), maize + cowpea-rapeseed (M + C-Rs), maize + cowpea-buckwheat (M + C-Bw), maize + cowpea-barley (M + C–B), maize + cowpea-garden pea (M + C-GP) and maize + cowpea–rajmash (M + C-R) in the main plot and three soil moisture conservation measures, no-mulch (NM), maize stover mulch (MSM) and maize stover + weed biomass mulch (MSM + WBM) in sub-plot were evaluated for four consecutive years (2014-18) at a Research Farm in fixed plot fashion. Results indicated that cowpea co-culture with maize and inclusion of winter crop increased maize yield by 6.2–23.5% over M-F. Among the systems, the M + C-GP recorded the highest crop productivity. The residual effect of MSM + WBM increased maize grain yield by 19.1% over NM. Cultivation of maize + cowpea-winter crops significantly improved the available N (3.2–12.9%), P (3.6–12.7%), K (1.9–26.3%), organic carbon (9.2–16.8%), microbial biomass carbon-MBC (15.2–43.9%) and dehydrogenases-DHA (17.2–42.3%) in soil at 0–15 cm depth as compared to M-F. The M + C-GP also recorded maximum net return (US $2460 ha−1), benefit:cost (B: C) ratio (2.86) and energy use efficiency (7.9%). The MSM + WBM recorded higher net return (US $1680 ha−1) and B:C ratio (2.46) over NM. Hence, cowpea + maize-garden pea (M + C-GP) along with the application of MSM + WBM is a sustainable production practice to intensify the organically managed maize-fallow system in rainfed regions of the EHR of India and other similar ecosystems.