Impact of Reclaimed Water Irrigation on Rice Yields and Quality

Abstract

Poultry and livestock farming wastewater is one of the main sources of agricultural non-point source pollution. Using reclaimed poultry and livestock farming wastewater for rice irrigation can not only provide nutrition for rice, but also reduce agricultural water consumption, and also further control non-point source pollution through the self-purification of rice ecosystem. It has been considered to be environmentally friendly and reliable for poultry and livestock farming wastewater treatment. However, the effect of reclaimed water irrigation on rice yield and quality is still unclear. In order to explore the effects of reclaimed water irrigation on rice yield and quality, we conducted a rice reclaimed irrigation experiment in the Erhai lake basin in 2017. The rice yield and quality were compared among different irrigation modes, different irrigation water quality and different fertilization schemes of reclaimed water. The results showed that the yield of W1F2, under intermittent irrigation with reclaimed water, was the highest, reaching 11.7t/hm2. The differences of rice yield and its components between different irrigation and fertilization methods were not significant. The yield and its components of rice under different irrigation and fertilization treatments were not significant. In terms of yield, the intermittent irrigation was 7.6% higher than that of flood irrigation. The amount of fertilizer applied by intermittent irrigation of reclaimed water was 7.0% less than that of clear water, and the yield increased by 3.5%. Correspondingly, the amount of fertilization of flood irrigation of reclaimed water is equivalent to that of clear water, which increases yield by 1.9%. In summary, the effect of reclaimed water irrigation on yield increase is obvious. There were significant differences in brown rice rate and chalky grain rate between different irrigation modes, which showed that the brown rice rate of intermittently irrigated rice was 0.7% smaller than that of flooded rice, and the white grain of intermittently irrigated rice was 45% larger than that of flooded irrigation. Intermittent irrigation has an adverse effect on the processing quality and appearance quality of rice. There were significant differences in brown rice rate, whole milled rice rate, gel consistency and depletion value under different irrigation water quality. The results showed that the brown rice rate and the depletion value of reclaimed water irrigation were smaller than those of clear water, and the whole milled rice rate and gel consistency were larger than that of clear water. Regularity, reclaimed water irrigated rice processing quality and cooking taste quality is better. In terms of nutritional quality of rice, the crude protein content in flooding treatment was 4.2% higher than that in intermittent irrigation, and the irrigation treatment of reclaimed water was 13.8% higher than that in clear water irrigation.