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Agricultural cropping systems involve the application of high fertilizer rates, which lead to phosphorus (P) losses via surface runoff to the aquatic environment, thereby resulting in severe eutrophication. Here, to evaluate the nutrient loss, we established three monitoring stations in Zhejiang Province, China, in each of which the crop types were double cropping rice, rice–wheat rotation, and vegetable cultivation. Field experiments were conducted with four treatments and three replications over a whole planting year. The four treatments at the same P application rate were: 1) no fertilization (control; CK), 2) chemical fertilization (CF), 3) substitution of 30 % chemical P in CF by organic P in solid sheep manure (OF) or in liquid biogas slurry (BS), and 4) substitution of 30 % chemical P in CF by organic P fertilizers (solid sheep manure or liquid biogas slurry) +1.5 t ha−1 polyacrylamide modified BC (PSB). The runoff losses of various P forms, that is, the total P, total dissolved P, particulate P, and colloidal P losses were analyzed. The total P concentration varied greatly with the crop growth stages. Compared with CF treatment, PSB treatment significantly reduced the concentration of P fractions in the runoff in all three cropping systems, while the OF treatment significantly reduced the particulate P and colloidal P concentrations by coating colloidal particles with organic carbon. However, BS treatment increased particulate P and colloidal P concentrations. Compared with CF treatment, PSB treatment reduced total P loss by 41.1 %, 29.7 %, and 37.8 % in the double cropping rice, rice–wheat, and vegetable systems, respectively. The PSB and OF treatments significantly reduced the particulate P and colloidal P losses, while BS treatment increased the loss of various P forms. Compared with the CF treatment, the PSB treatment significantly increased the available P contents by 12.7–85.4 mg kg-1, and decreased the colloidal P contents by 26.7 %–51.4 % in the soils examined. The results of the redundancy analysis confirmed that P loss via runoff was mainly caused by differences in the P inputs and crop types. The results of this study highlight the important role of PSB in reducing P loss via runoff from agricultural cropping systems.

Chinese ecological agriculture (CEA) is a relatively recent agricultural and rural development approach, which has emerged in light of continuous efforts in exploring sustainable agriculture and rural development in modern China. Based on the discussion of the ecological agricultural concepts and practices in ancient China, as well as the agro-ecological problems that have emerged in modern China, this paper introduces the emergence and development process of CEA and analyses its concept, connotation and underlying principles. In addition, the processes as well as some practical principles in organizing CEA projects are discussed, and the major CEA development patterns currently practiced in China are introduced. Using the Fushan Integrated Ecological Farm in Fushan village, Zhejiang Province, a typical CEA project in south China, as an example, the practical organization process of a CEA project is introduced as well as the significant benefits achieved by the launching of an appropriate CEA project in China’s rural areas. The successful practices of a variety of CEA projects with various development patterns and models that have been developed with adaptation to various natural and socioeconomic conditions across China justify the rationality as well as applicability of the CEA approach, showing its important relevance to agricultural and rural development in China.