Nutrition characteristics in root surface and rhizosphere soils of direct-seeding rice in rice-duck eco-farming system

Soil organic carbon, N, P, K contents and pH in root surface and rhizosphere soils of early season rice in rice-duck eco-farming system and mono-cropping rice system were investigated in a field plot experiment. The results show that the soil pH in root surface and rhizosphere of rice in rice-duck eco-farming system is increased by 4.41%, 0.85% and total N is decreased by 0.11 g·kg^-1, 0.11 g·kg^-1 compared with those in mono-cropping rice system, respectively, while changes in total P and total K contents are not statistically significant. Available N, available K in rice root surface soil in rice-duck eco-farming system are 30.80 mg·kg^-1, 17.93 mg·kg^-1 higher and available P is 8.66 mg·kg^-1 lower than those in mono-cropping rice system, however, available N and available K in rhizospere soil are 15.13 mg·kg^-1, 7.61 mg·kg^-1 lower and available P is 9.66 mg·kg^-1 higher than those in mono-cropping rice system. Compared with the mono-cropping rice system, in rice-duck eco-farming system, active organic carbon and high-active organic carbon in root surface soil are increased by 2.17 g·kg^-1 and 0.56 g·kg^-1 respectively, total organic carbon is deceased by 0.99 g·kg^-1, and total organic carbon, active organic carbon and mid-active organic carbon in rhizosphere soil are decreased by 2.39 g·kg^-1, 2.64 g·kg^-1 and 0.72 g·kg^-1, respectively. It is illustrated that in rice-duck eco-farming system, available K and active organic carbon are accumulated in root surface soil, and available P is accumulated in rhizosphere soil. Hence, soil nutrient status in root surface and rhizosphere in rice-duck eco-farming ecosystem are significantly improved, which probably have a good effect on nutrient absorption of rice.