Studies On Leaching Of Controlled-Release Nitrogen Fertilizer In Simulation Sand-based Turf-bed Of Sport Filed And Its Interaction Effect With PP₃₃₃

There is severe risk of nutrient leaching in sand-based turf bed of sport filed. According to the potential problem of nutrient leaching in sand-based turf bed of sport filed, comparing to treatment of no fertilizer, using PVC tube to simulate the foundation structure of sports turf ground, this paper studied nitrogen transport and leaching law between controlled-release nitrogen fertilizer and urea in sand-based turf bed of sport filed through laboratory simulation in order to provide scientific basis for controlling nitrogen leaching effectively and preventing water eutrophication .This paper made controlled- release nitrogen fertilizer and PP₃₃₃ apply to sports turf ground in northern China and evaluated the effect on morphological index,cold- resistance, rhizosphere nutrients index and nutrient leaching which provided evidence for controlled-release nitrogen fertilizer and PP₃₃₃ apply to sports turf ground in order to meet the needs of sports competition in north, improved the quality of sport turf and prolonged utilization period of sports turf ground in winter.The results indicated that there was a significant effect of fertilization on the pH and EC of eluent in sand-based turf bed. There was stable change trend on pH and EC of controlled-release nitrogen fertilizer during the whole test process and advantages of nutrient release steadily compared with urea. Controlled-release nitrogen fertilizer could significantly decrease nitrogen leaching loss rate. With the increase of urea dosage, nitrogen leaching loss rate of urea increased. However, nitrogen leaching loss rate of controlled-release nitrogen fertilizer had not change significantly. The amount of controlled-release nitrogen fertilizer was four times of urea, however, their nitrogen leaching amounts were equal.Controlled-release nitrogen fertilizer and PP₃₃₃ had significant promotion of density, tiller number, green degree and green period of turf grass, and there was a better effect together. PP₃₃₃ had significant inhibitory effect on coverage, homogeneous degree, height, biomass, growth potential of turf grass, but controlled-release nitrogen fertilizer had promoting effect on above indexes. Combined application of controlled-release nitrogen fertilizer and PP₃₃₃ not only inhibited spindling of turf grass and prevented excess nutrients loss from carrying away by turf mowing , but also ensured moderate growth of turf grass and reached acceptable level for various index.Controlled-release nitrogen fertilizer and PP₃₃₃ significantly decreased relative conductivity and MDA content of turf grass, membrane lipid peroxide and membrane injury degree, effectively improved protective enzyme activity of turf grass, and had an important effect on improving cold resistance of turf grass. Combined application of controlled-release nitrogen fertilizer and PP₃₃₃ had osmoregulation substance accumulated and decreased freezing injury of turf grass obviously.During the experiment, available nitrogen and NO₃^-- N contents of the rootzone mixes increased with nitrogen application increasing. The available nitrogen and NO₃^-- N contents of the rootzone mixes which was treated by controlled-release nitrogen fertilizer had been maintained at a high level and there was a smooth upward trend.The contents of NO₃^-- N and NH₄⁺-N in eluent was increasing with fertilizer amount. The leaching rates of controlled-release nitrogen fertilizer were lower than 3%, as equal as simulated experiment indoor. Controlled- release nitrogen fertilizer had greater influence on nutrient indicator of rootzone mixes and eluent than PP₃₃₃.