Crop Coefficient and Water Productivity in Conventional and System of Rice Intensification (SRI) Irrigation Regimes of Terrace Rice Fields in Indonesia


Chusnul Arif, Kazunobu Toriyama, Bayu Dwi Apri Nugroho, Masaru Mizoguchi


The current study initiated to investigate crop coefficient (Kc) and water productivity between conventional and System of Rice Intensification (SRI) irrigation regimes of terrace rice fields in Indonesia. Kc value represents plant responses to available water in the fields and its information is very important to determine crop evapotranspiration. The field experiments were conducted in the terrace rice fields belong to the local farmer located in Wonogiri, Central Java (S 7o47’18.66â€, E 111o5’51.26â€) during 21 July – 7 November 2014 in the dry season. Here, there were two irrigation regimes with three replications, i.e. conventional flooding (FL) regime and SRI with intermittent irrigation (II) regime. Water level in each regime was measured by pressure sensor, while weather parameters such as solar radiation, air temperature, precipitation, etc were measured by particular sensors and connected to the developed field monitoring system. Based on weather and water level data, we estimated the average Kc values for FL regime were 1.01, 1.02, 1.09 and 1.05 in the initial, crop development, reproductive and late growth stages, respectively. Meanwhile, the average Kc values under SRI regime were a little bit lower than that FL regime. Their values were 1.00, 0.96, 1.02 and 1.04 for the initial, crop development, reproductive and late growth stages, respectively. The reason was probably due to minimum soil evaporation under the drier soil condition. However, lower Kc values were not corresponded to the production of grain yield. Although it was not significant difference, we recorded that SRI regime produced 8.05 ton/ha grain yield, while FL regime was 7.63 ton/ha. Accordingly, with less irrigation water, SRI regime has higher water productivity than that FL regime


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