长兴县合溪水库集雨区苗木地不同施肥管理模式对径流磷素流失的影响

为保护主要饮用水源合溪水库水质,长兴县将合溪水库集雨区农业种植结构向苗木种植方式调整,但缺乏优化施肥管理模式。针对该问题,选取集雨区典型苗木种植地进行径流小区定位试验,设置了撒施(对照)、地膜覆盖、秸秆覆盖、区外设置植草缓冲带、条施、穴施6个处理,研究不同施肥管理模式下苗木地径流磷素流失特征,筛选最优施肥管理模式,实现最大化的削减农田磷素流失。结果表明:不同施肥管理模式下,苗木地地表径流年总磷素径流流失通量大小顺序为:撒施(对照)地膜覆盖条施穴施区外植草缓冲带秸秆覆盖,撒施(对照)、地膜覆盖、条施、穴施、区外设置植草缓冲带和秸秆覆盖六种施肥管理模式下的年总磷素径流流失通量分别为:9.60、9.14、5.49、4.44、2.48、1.37 kg hm-2a-1,说明穴施、区外设置植草缓冲带和秸秆覆盖是较佳的施肥管理模式,若将其优化组合将显著消减合溪水库集雨区苗木地径流磷素流失及其对合溪水库水质的潜在影响。此外,不同施肥管理模式下,苗木地径流水样磷素流失的首要形态均为颗粒态磷,其次为溶解态磷,其中,撒施(对照)、地膜覆盖、秸秆覆盖、区外植草缓冲带、条施和穴施小区径流年均流失的颗粒态磷占流失总磷的比例分别是66.09%、70.69%、67.97%、71.63%、68.11%和67.87%。

Influence of different fertilization management modes on phosphorus loss in run-off from nursery land in the catchment area of Hexi reservoir in Changxing county

In order to protect the main source of drinking water and ensure the quality of stream water from the Hexi reservoir, the government of Changxing county have adjusted the agricultural planting structure to nursery land in the catchment area of Hexi reservoir; however, the use of an optimized fertilization management mode is lacking. With this aim, site-specific observations were carried out in the catchment area of Hexi reservoir. Six fertilization management plots for typical nursery land were selected, including broadcast placement (contrast), plastic mulching, straw mulching, setting buffer for planting grass around nursery land, band placement, and hole placement, to explore the characteristics of different fertilization management modes on phosphorus loss in surface runoff, to screen the best fertilization management mode and to implement the the best method to reduce farmland phosphorous loss. The results showed that under different fertilization management modes, the concentration of annual phosphorus run-off erosion was in the order: broadcast placement (contrast) > plastic mulching > band placement > hole placement > setting buffer for planting grass around nursery land > straw mulching. The mean annual run-off loads of total phosphorus from broadcast placement (contrast), plastic mulching, band placement, hole placement, setting buffer for planting grass around nursery land, and straw mulching were 9.60, 9.14, 5.49, 4.44, 2.48,1.37 kg hm^-2 a^-1, respectively. This indicates that hole placement, setting buffer for planting grass, and straw mulching were the best fertilization management modes. Additionally, the optimal combination of fertilization management modes for nursery land of the catchment area of Hexi reservoir in Changxing county would significantly reduce the non-point source output phosphorus run-off of nursery land and reduce the potential impact on water quality from the Hexi reservoir. In addition, phosphorus particles were the main and first form of phosphorus loss in run-off and the next was dissolved phosphorus under all fertilization management modes. Furthermore, with the broadcast placement (contrast), plastic mulching, straw mulching, setting buffer for planting grass around nursery land, band placement, and hole placement, the annual run-off loss of phosphorus particles accounted for about 66.09%, 70.69%, 67.97%, 71.63%, 68.11% and 67.87%, respectively, of the total phosphorus.