添加氮磷钾元素对典型草原区割草地植物群落组成及草地质量的影响

Effect of Appling N、P、K to Mowing Grassland on Plant Community Composition and Grassland Quality of Typical Steppe

试验发现添加氮磷钾元素对割草地产量、群落组成及草地质量的影响有:(1)对一年割一次的草地,添加氮磷钾水平K2(120kg.hm-2)的小区增长最为显著;对一年割两次的草地,惟有最高水平K4(180 kg.hm-2)可见到显著的增产效果;对于不割草对照区,添加氮磷钾元素有一定增产作用,但没有达到显著性水平(p<0.05)。(2)添加氮磷钾元素能使羊草和大针茅种群在一年割一次和不割草对照中都表现出等补偿和超补偿,但在一年割两次中均为不足补偿;对糙隐子草则相反,在不割草对照中其仅为等补偿,而在割草处理后刈割频度越高超补偿现象越明显。(3)添加氮磷钾元素可提高草地质量,其中K2水平添加量的效果最为明显,草地质量维持的最好。

In the grassland region of Inner Mongolia, herdsmen had always mowed tall grass in autumn to feed livestock in winter. The grassland had been degenerate more and more because of being mowed year by year. Considering these problems, the research studied and analyzed the effect of N ,P,K Application to mowing grassland on the standing crops, community structure and grassland quality of Stipa grandis grassland. The results showed： （1） In the plots mowed once a year, the community standing crops was higher after appling N ,P,K than that of control plots, not only in the same year, but the plots with gradient K2（ 120kg·hm^-2） ,K4（ 180kg·hm^-2）） also had significantly higher productivity in the next year after application. In the plots mowed twice a year, only with highest gradient （K4） could have significantly higher standing crops compared to control plots. As far as no mowing plots were concerned, N, P, K Application had worked somewhat. （2） In the three main populations, Stipa grandis, Leymus chinensis and Cleistogenes squarrosa, after appling N ,P, K, Stipa grund/s and Leymus chinensis showed equal and super compensation on standing crops in control plot and plot mowed once a year, while in plot mowed twice a year they were deficient compensation, while Cleistogenes squarrosa showed opposite rules, their standing crops were equal compensated in control plot, but super compensated in plots being mowed after appling N, P, K; （3） N, P, K application not only could ensure productivity of grassland mowed once a year, but improved the grassland quality in some degree. The effect of k2 gradient on grassland was most positively.