Effect of traditional irrigation on production, water efficiency and methane emission of rice crop

Abstract

The generation of information that serves as an argument in the search for alternatives for sustainable management of irrigation in rice is an important current demand. Given this, the present study aimed to evaluate traditional irrigation (continuous flooding) through crop production, water use efficiency (WUE) and methane emission; taking as reference an irrigation alternative without flooding (aerobic), in which soil moisture was maintained between saturation and close to field capacity. With these two irrigation alternatives, an experiment of four-square plots of 25,0 m on each side was installed, defining nine sampling points of 4.0 m2 within each of them. The INIAP 11 rice variety was used, with sowing by transplant. Irrigation management was carried out using the pan evaporation method, together with the registration of tensiometers for soil moisture control. In the crop, tillering, percentage of empty grains, weight of 1000 grains and yield were evaluated. For the measurement of methane, two acrylic chambers of 1.0 m side and 1.2 m high were used, together with a portable gas meter. No significant differences were detected in crop production, but a substantial increase in WUE from 3,649 m3·kg-1 to 0,312 m3·kg-1 was found The methane emission rate was significantly higher in traditional irrigation, with a maximum of 4.33 mg·m-2·h-1, while, in aerobic irrigation, this value was 1.69 mg/m2/h. It was concluded that the irrigation without flooding has advantages regarding WUE and methane emission with respect to traditional irrigation while keeping the crop production unchanged.