Studies On Prevention And Control Techniques Of The Nitrogen And Phosphorus Loss In The Intensive Management Phyllostachys Praecox Stands

Since the 1980s, heavy fertilization and cover for surface heating in winter as the core cultivation technique for pre-season and efficient production of bamboo shoots has been widely applied in Phyllostachys praecox stands.The technique leads to huge amount of nitrogen (N) and phosphorus (P) losses in the production process, and the surrounding water bodies of Phyllostachys praecox stands were polluted. Therefore, field monitoring analysis and runoff plot experiments were conducted from 2013 to 2014 at Taihuyuan town, linan city. Studies on reduction and intercept of N and P by source-sink landscape combination systems based on bamboo and paddy fields, with reduced fertilization measures and shrub buffer were carried out in order to construct the optimal prevention and control system of N and P losses in the intensive management of Phyllostachys praecox stands.The main results were as follows:Large amount of fertilization and winter cover in Phyllostachys praecox stands resulted in the decrease of soil pH and the accumulation of soil organic matter, total nitrogen (TN), alkali solution nitrogen, total phosphorus (TP), available phosphorus and available potassium in the soil. Accumulated of N and P in the soil were easily lost with rainfall runoff and got into the water. Source-sink landscape combination systems based on bamboo and paddy fields could effectively reduce runoff N and P from bamboo fields by paddy fields, the concentrations of runoff TN and TP being reduced by 47.07% and 62.83%. Based on the premise of yield guarantee, bamboo conventional fertilization-paddy reducing fertilization was the optimal of combination type. The effect of area ratio between bamboo and paddy fields on controlling N and P losses was not obvious. Therefore, agricultural non-point source pollution could be controlled by land use allocation patterns within agricultural systems.There was a highly significant positive correlation between surface runoff under different treatments and rainfall. Through two years of sample determination, reducing fertilizer treatment could reduce the average concentrations of total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO3-), ammonium nitrogen (NH4+), dissolved total phosphorus (DTP) and particulate phosphorus (PP) by 39.70%, 21.95%,35.14%,47.16%,17.60% and 33.52%, respectively, in the runoff water from bamboo fields as compared with conventional fertilization, and could reduce the cumulative runoff losses of TN, TP, NO3-, NH4+, DTP and PP by 34.65%,16.06%, 30.15%,41.73%,10.29% and 30.26%, respectively.The dissolved nitrogen (DN) and DTP were the main components of runoff N and P from Phyllostachys praecox stands. Bamboo shoot yield of Phyllostachys praecox stands was reduced by 9.05% for reducing fertilizer treatment, but the economic benefit was higher than that of conventional fertilization by 696 yuan hm-2.Shrub buffer could effectively reduce the amount of runoff from bamboo plots. Shrub buffer could reduce the concentrations of TN and TP by more than 64% and 61% in runoff water from Phyllostachys praecox stands. Shrub buffer could reduce the cumulative losses of TN, TP, NO3-, NH4+, DTP and PP by 87.49%,78.25%,84.14%, 93.99%,78.80% and 76.52%, respectively, in runoff water from conventional fertilization bamboo plots, and could reduce the cumulative losses of TN, TP, NO3-, NH4+, DTP and PP by 79.32%,75.55%,75.98%,86.40%,78.12% and 67.57%, respectively, in runoff water from reducing fertilization bamboo plots. It is obvious that shrub buffer can significantly reduce the accumulated losses of N and P in runoff water from Phyllostachys praecox stands.In conclusion, source-sink landscape combination systems, reducing fertilization measures and shrub buffer could all effectively reduce the runoff losses of N and P from intensive management Phyllostachys praecox stands.