Effect of rice varieties mixed-cropping with duck raising on nutrient dynamics in paddy soils

Rice-duck farming systems with different varieties of rice mixed-cropping could produce excellent ecological effects. However, it is for now largely unclear whether the synergy of the two farming systems (rice-duck farming and rice varieties mixed-cropping) could improve ecological conditions and production efficiency to have "1+1>2" effect when concurrently implemented. Because of large-scale rice monoculture with high application of pesticides and fertilizers, food and eco-environment security has increasingly worsened. To meet the demands for diverse taste and high-quality organic rice, and to further explore the feasibility of biodiversity model in different rice varieties mixed-cropping systems and duck-rice mixed-farming, an innovative double rice varieties mixed-cropping along with duck raising was set up and studied. To test the effects of the farming system on soil nutrient dynamics and rice quality, six different treatments were set up-including ‘Shengbasimiao’ rice variety mono-cropping with conventional farming practice (SC), ‘Shengbasimiao’ rice variety mono-cropping with duck raising (SD), ‘Shengbasimiao’ rice variety mono-cropping (CK1), mixed-cropping of rice varieties of ‘Shengbasimiao’ and ‘Huajingxian 74’ with conventional farming practice (MC), combined rice varieties of ‘Shengbasimiao’ and ‘Huajingxian 74’ mixed-cropping and duck raising (MD), and rice varieties of ‘Shengbasimiao’ and ‘Huajingxian 74’ mixed-cropping (CK2). After early and late rice planting in the first year, organic matter content of paddy soils under treatment MD was significantly higher than that under the other treatments. Although soil total nitrogen content in early rice planting under treatment MD was significantly lower than that under treatment MC, it was significantly higher than that under other treatments. After early and late rice planting, it was noted that soil alkali-hydrolyzable nitrogen content under treatment MD was significantly increased compared with that under the other treatments. The content of soil available phosphorus under CK1 was the highest among all the treatments. Generally, the average content of soil available phosphorus under rice varieties mixed-cropping systems was higher than that under rice variety mono-cropping systems. After rice cropping for one year, the contents of soil total potassium and available potassium under treatment MD were higher than those under the other treatments. Rice brown rate, milled rice rate, amylase content and gel consistency under MD were higher than those under the other treatments. However, the rate of chalky rice under MD was lower than that under the other treatments. In conclusion, the integrated farming systems of rice varieties mixed-cropping and duck raising improved soil nutrient and rice quality. This successfully tried a new farming system that ensured ecological health, and high-quality and high-yield rice production.