Integrated Nitrogen and Phosphorus Management in Rice Under Flood-Prone Lowland Situation

Abstract

ABSTRACT Crop survival as influenced by integrated N management (INM) in rice variety ‘Gayatri’ was studied following 10 days of complete submergence at maximum tillering stage during 2003 and 2004 in the Central Rice Research Institute, Cuttack, India. Organic N sources such as farmyard manure (FYM) and Sesbania aculeate were included in INM along with fertilizers N and P. Crops with the combined organics of FYM and Sesbania survived better after submergence, which was attributed to higher biomass production, less tiller mortality, greater root development, and higher critical N content in leaf, as compared with other treatments. These crops produced significantly higher grain yield (2.97 and 3.09t ha−1 in 2003 and 2004) compared with those with application of FYM (2.48 and 2.61 t ha−1), use of Sesbania (2.24 and 2.35 t ha−1) and chemical fertilizer N (1.98 and 2.07 t ha−1) alone. In both the years, application of P also led to higher grain yields (2.40 and 2.52 t ha−1) compared with no application of P (2.19 and 2.29 t ha−1). Interaction of INM with P showed that application of P with the combined organics increased grain yield by 13.1–13.7%, followed by that with FYM (10.16–12.2%), Sesbania (8.37–8.89%), and fertilizer N (7.33–8.04%). In both the years, greater nutrient utilization as evidenced by N use efficiency (29.2 and 29.7 kg grain per kg N ha−1), N uptake (54.0 and 57.0 kg ha−1), and N recovery (35.0 and 41.5%) was attributed to the crops with combined organics. P use efficiency (10.5 and 11.5 kg grain per kg P ha−1), P uptake (14.9 and 16.5 kg ha−1), and P recovery (28.5 and 31.5%) were higher in the treatments with applied P. Thus the study revealed that application of both FYM and Sesbania in combination with fertilizers N and P in rice improved crop growth resulting in increased grain yield and nutrient utilization in flood-prone situations. Therefore, it is recommended to follow INM that included FYM and Sesbania in combination with both fertilizers N and P in rice cultivation for increasing grain yield in flood-prone lowland situations.