Integrated System of Rice Intensification (ISRI) for Enhancing Land and Water Productivity

Abstract

Enhancing food crop production under increasing water constraints and greater climatic variability challenges us to improve both land and water productivity. In many areas, where substantial rainfall occurs over a few months and rice cultivation is dependent upon only rainwater faces either heavy rainfall or long dry spells, often results in low productivity and environmental pollution. A 2-year field experiment was conducted with an aim of enhancing the economic productivity of land and water under rainfed conditions, where mostly only a rainy-season rice crop can be grown. Four possible rice cultivation systems were evaluated: (i) conventional rice cultivation methods under rainfed conditions, (ii) System of Rice Intensification (SRI) methods adapted to rainfed conditions, (iii) rainfed SRI methods with drainage and supplementary irrigation to ascertain what these facilities could add, and (iv) SRI methods utilizing rainwater harvesting to collect excess rainwater and store it for utilizing aquaculture and horticulture crops also with a provision of supplementary irrigation for rice crop. Changes in rainfed rice cultivation through adaptations of SRI practices increased grain yield by 53% compared with conventional rice production method. Significant improvements were observed in the morphology and physiology of rice plants grown with adapted SRI practices. Phenotypic improvements included: greater xylem exudation rate, higher light interception by the canopy, and more chlorophyll content, greater light utilization, and higher photosynthetic rates in the leaves during the flowering stage. These changes were responsible for the improvement in yield-contributing characteristics and the higher grain yield compared with conventional production methods. Drainage and supplementary irrigation as expected improved both grain yield and water productivity for rainfed SRI. Further, integrating aquaculture and horticulture with SRI management, plus having harvested rainwater available in an in-field refuge, increased rice productivity and enhanced net water productivity. This raised net income per unit of water substantially compared with conventional rice cultivation. Combining SRI rice cultivation with aquaculture and horticulture, harvesting rainwater and providing some supplementary irrigation, looks promising for improving food security under future conditions of water scarcity and climate change. This farming systems innovation could be especially important for disadvantaged, food-insecure households living and cultivating under less-favorable circumstance.