施氮对黑麦草草坪生长及土壤硝态氮的影响

随着草坪种植面积的不断增加,施肥引起的环境问题备受关注。为明确氮肥对多年生黑麦草(Lolium pe-renne)生长及对土壤硝态氮残留的影响,本研究采用盆栽试验,设计不同施氮水平(0、100、150、250、350kg.hm-2.a-1),测定草坪草生长速度、地上生物量、叶绿素含量及土壤中硝态氮的残留量。试验结果表明,0～250 kg.hm-2.a-1施氮范围内,草坪草生长速率、地上生物量和叶绿素含量均随施氮量的增加而增加,施氮量达350 kg.hm-2.a-1时各指标均开始下降。根下层土壤硝态氮的残留量约占根系层的一半,150 kg.hm-2.a-1施氮水平下各土层中的氮残留量与对照无明显差异,说明此施氮量基本能够满足草坪生长需要的氮量。超过250kg.hm-2.a-1时,土壤中的氮残留量逐渐增加,达到350 kg.hm-2.a-1时根下层的氮残留量达到最高值9.01mg.kg-1。从兼顾草坪观赏价值和环境安全的角度考虑,东北地区黑麦草草坪的施氮量为250 kg.hm-2.a-1较为合适,若超过此量,就会引起硝态氮淋失,增加氮污染的危险性。

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 kg·ha-1·a-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 kg·ha-1·a-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 kg·ha-1·a-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 kg·hm-2·a-1, which just could satisfy the turf demand. Nitrate residue in soil increased when nitrogen application exceeded 250 kg·ha-1·a-1, reaching to the highest value 9.01 mg·kg-1 at the rate of 350 kg·ha-1·a-1. Considering the ornamental value and environmental safety, the treatments of urea with concentration of 250 kg·ha-1·a-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 kg·ha-1·a-1.