Water productivity analysis in irrigated central rice production area of SolokRegency, Indonesia

Abstract

To feed the increasing world population, the demand for food and consequently irrigation water is predicted to increase in the future. However, the amount of water available for agriculture is increasingly becoming uncertain in the face of global climate change. Therefore, improvement in water productivity is necessary for sustainable production of crops such as rice. Water productivity varies across regions and across fields within a region, and is dependent on several factors such as crop patterns, climate patterns, irrigation technology and field water management, land and infrastructure, and other inputs, including labor, fertilizer, and machinery. The objective of this study was to estimate water supply and demand in Sumani watershed, a primary rice-producing region, to analyze water productivity for sustainable rice production. Approximately 30% of the area in Sumaniis paddy fields, which depend on the availability of water resources. In this area. Approximately 67% of the rice fields are cultivated three times a year. In general, the planting schedule of rice is divided into three periods: main planting season (wet season), Gadu planting season (planting in the end of wet season and harvesting in the dry season), and dry planting season. Although the planting schedules are not uniform, we assumed these as uniform, to simplify the analysis, by using majority cropping schedule in the study site. To ensure water availability in the dry season, four types of irrigation systems were used: technical irrigation (TI), semi-technical irrigation (STI), simple irrigation (SI), and non-government irrigation (NGI). The results showed thatdepending on the planting season and irrigation system, water productivity varied from 0.33 kg/m3 in the Gadu season in areas irrigated by the SI and NGI systems to 0.73 kg/m3 in the wet season in area irrigated by the TI system. The average water productivity in the study area was 0.53kg/m3. Water productivity in this study area was lower than the average water productivity in other rice production areas in Java and Bali.