Rice is one of the world’s three leading cereal crops and is an important food source for nearly half of the world's population. It is therefore necessary to increase the production of rice in order to achieve the SDGs. However, most of the rice producing areas in the tropics depend completely on rainfed rice cultivation, and the yield is about half that of irrigated rice cultivation. Rainfed rice cultivation is a system in which most of the water required for rice growth is covered by rainfall, and water management is difficult unlike the irrigated rice cultivation system. For this reason, rice farmers have to rely on their experience-based intuition which has become unreliable due to the effects of climate change in recent years. Technological development is necessary to stabilize the production of rainfed rice farmers. In addition, the rainfed rice cultivation areas are also areas with low soil fertility and poor nutrient supply capacity especially for nitrogen. Therefore, proper application of fertilizer is required to achieve high yields. Paddy water is essential for application of fertilizer, but it is extremely difficult in rainfed paddy fields because there may be no water when farmers need to apply the fertilizer, or downpours may occur after application of fertilizer. Moreover, fertilizer is an expensive commodity for rainfed rice farmers so that rice is often cultivated with one-shot basal fertilizer or with no fertilizer at all in most cases. In order to increase yields in rainfed paddy fields, it is necessary to overcome the problems of water and nutrient supply.

Since 2010, JIRCAS has been conducting research, development and technical validations of the weather-rice-nutrient integrated decision support system (WeRise) in collaboration with the International Rice Research Institute (IRRI, Headquarters: Philippines) through an international research project supported by the Ministry of Agriculture, Forestry and Fisheries (MAFF). Field validations of WeRise were conducted in rainfed rice fields in North Sumatra and West Nusa Tenggara, Indonesia, and Iloilo, Nueva Ecija and Tarlac, Philippines, and the results have been published in the journal Agriculture. Demonstration tests in the Philippines and Indonesia have shown that WeRise can be used to determine the optimum sowing period and improve the efficiency of fertilizer application. This allows rainfed rice farmers to manage their resources and improve farming plans.

Reference
https://www.mdpi.com/2077-0472/11/4/346
Hayashi K. et al. Evaluating the predictive accuracy of the weather-rice-nutrient integrated decision system (WeRise) to improve rainfed rice productivity in Southeast Asia. Agriculture (2021). doi.org/10.3390/agriculture11040346

Contributor: HAYASHI Keiichi (Director, Environment Program)