Crop performance and soil-plant nutrient dynamics in rice-lentil system altered with rice cultivation practices in alkaline soil

Abstract

Aerobic or partially-aerobic rice cultivation techniques like direct-seeding of rice (DSR) and system of rice intensification (SRI) are gaining recognition, particularly for water-saving. However, their productivity is often constrained by several deficiencies in the soil-plant system (crop nutrition in particular). The study aimed to assess crop eco-physiology and soil-plant nutrient dynamics in rice-lentil system in an alkaline Fluvisol as influenced by different rice cultivation techniques (RCT) viz., DSR, SRI and conventional transplanted flooded-rice (PTR). The lower (9–11 %) yield of DSR crop compared to PTR crop was attributed to reduced root growth, effective tiller, and panicle and seed weights. Likewise, the SRI crop yield was lower (4–7 %) than the PTR crop. The reduced availability of soil KMnO4-N (7%) and Olsen-P (9%) in the rice seasons caused lower N (12–14 %), P (10 %), K (5–7 %) accumulations in DSR crop as compared to PTR crop (p < 0.05). Meanwhile, the SRI cultivation practice caused a decrease in Olsen-P (6%) during the rice seasons and lower crop macro-nutrient acquisition compared to the PTR crop. Sensor-based indices indicated a suboptimal N nutrition and higher leaf flavonoids accumulation in the DSR crop. The DSR crop exhibited higher post-anthesis nutrients (N, P) remobilization, physiological and internal nutrient utilization efficiencies over the SRI and PTR crops. The higher nodulation (21–31 %), root growth (8–10 %), and yield of lentil (10–16 %) in the DSR treatment compared to the SRI and PTR treatments suggested adverse impacts of wet-tillage (puddling) on the subsequent crop. The system productivity and economic gain were comparable in all the RCT treatments; however, the DSR and SRI cultivation practices increased the water productivity by 64 % and 44 % over the PTR. Thus, in alkaline soil, particular attention is warranted to improve N and P nutrition in non-flooded rice crops (DSR in particular) to sustain their yield potential. Also, real-time N management using sensor-based indices and trait-based cultivar selection (root growth and source-sink translocation) could be strategic options for improving DSR productivity.