Non-point source pollution control experiment and ecological response of ecological landscape type irrigation and drainage system

Abstract: The current irrigation and drainage system in land renovation was mainly designed and constructed to heighten efficiency of irrigation and drainage, structure safety and convenient management, which, however, somewhat neglected ecological landscape design, exerting an inappropriate influence on the biological habitat and agricultural non-point source pollution. Therefore, the aim of this paper is to design an ecological landscape irrigation and drainage system and realize more comprehensive benefits. First of all, originated from the traditional agricultural drainage and irrigation system, irrigation and drainage with an ecological ring-ditch was designed by using the principle of mutually-beneficial symbiosis of paddy, red duckweed, fish and vegetable planting plates, which realized the multifunctional stereo development of rice paddy pisciculture, vegetable planting and so on. Meanwhile, the roundabout biochemical pond was designed at the ecological ring-ditch drainage sluice, which was used as the treatment device of agricultural non-point source pollution. Then, ecological landscape lateral canal and lateral ditch was designed, which was made up of vegetation type diaphragm blocks, hornworts, vegetable planting plates, fish, Jumping type antiskid ecological plate and plant ecological community. What is more, by using the land reclamation project in shanghai as the experimental area, the rice growth cycle (6-10 months) as study period, the COD, NH4+-N, TN and TP as test indicators, and three monitoring sections as monitoring points, experimental of non-point source pollution prevention effects were made comparisons between system 1, system 2 and system3. The system 1 was constituted by the irrigation and drainage system using ecological ring-ditch, roundabout biochemical pond and lateral ditch wetlands. The system 2 was constituted by the irrigation and drainage system using underground pipe and current lateral ditch. And the system 3 was constituted by the irrigation and drainage system using open channels and ditch and current lateral ditch. Finally, we introduced ecological service value model to evaluate ecological response of the ecological system of farmland water conservancy brought by the ecological landscape type of irrigation and drainage system.The results showed that: 1) The ecological landscape type of irrigation and drainage system consists ecological ring-ditch, roundabout biochemical pond and lateral ditch wetlands accompanied with the principle of mutually-beneficial symbiosis of paddy, red duckweed, fish and vegetable planting plates, realizing rice paddy pisciculture and agriculture modernization. It was a success not only for the farmland benefit but also providing the important practical significance of exploring environmentally friendly high-efficiency systems for ecological agricultural uses; 2)The average removal rate of ecological landscape type of irrigation and drainage system were77.57%、78.99%、69.77%、73.74% respectively. Firstly, red duckweed, vegetable planting plates, microbial can degrade pollutants in the ecological ring-ditch; Secondly, biochemical pond removed pollutants with the absorption and transformation by microorganism and plants, as well as sedimentation and filtration; Finally, the lateral ditch removed pollutants through microbial absorption and transformation, sedimentation and filtration, matrix adsorption and so on; 3)A big ecological response was generated from the ecological system of farmland water conservancy brought by the ecological landscape type of irrigation and drainage system. The positive effect was 49.4×103 yuan, which is 45 times than the negative effect. In conclusion, the ecological function of the ecological landscape type of irrigation and drainage system was enhanced in climate regulation, water conservation, waste disposal, biodiversity conservation, soil conservation and aesthetic landscape and so on.