Effects of different nitrogen application on turf growth of Lolium perenne and nitrate residue in soil

Along with the planting area of lawn expanding in China, the environmental problem caused by fertilization has attracted much attention now. This study was aimed to analyze the effects of nitrogen application on growth of Lolium perenne and nitrate residue in soil. By pot experiment, nitrogen application took five levels（0,100,150,250 and 350 kgha-1a-1）.After fertilization, the growth rate, aboveground biomass, chlorophyll content of L.perenne and nitrate residue in soil were analyzed. The results indicated that, within the range of 0～250 kgha-1a-1 nitrogen application, growth rate, aboveground biomass and chlorophyll content of turf increased with the increasing of nitrogen level, while they all decreased when nitrogen level reached to 350 kgha-1a-1. Nitrate residue in root down layer soil was nearly half of that in root zone layer soil. Nitrate residue of different soil depth was not significantly different from the control(CK) when nitrogen application reached 150 kghm-2a-1, which just could satisfy the turf demand. Nitrate residue in soil increased when nitrogen application exceeded 250 kgha-1a-1, reaching to the highest value 9.01 mgkg-1 at the rate of 350 kgha-1a-1. Considering the ornamental value and environmental safety, the treatments of urea with concentration of 250 kgha-1a-1 was the best for Northeast area, while it would lead to nitrate leaching to form the potential danger of nitrogen pollution when nitrogen application exceeded 250 kgha-1a-1.