民勤绿洲退耕地土壤养分分布特征研究

The Study of Soil Nutrient Distribution in Abandoned Lands in the Minqin Oasis

为了更加科学合理地管理和利用植被资源,以石羊河下游的典型区——民勤县退耕地为研究对象,通过对石羊河下游地区退耕地植被恢复过程中不同恢复年限土壤养分变化分布特征进行分析。结果表明：（1）土壤中N肥含量退耕年限的增加呈波动式上升的趋势,但在同一年限退耕地中随土层的加深而逐渐减小,退耕后1-10年,群落中大多为1年生草本植物和宿根植物,其根系较浅,土层N含量变化的幅度较小;15-30年,1年生草本逐渐被多年生草本和灌木所代替,植物根系深度达到20-40 cm N含量变化的幅度相对较大;50年后,趋于稳定。（2）P含量在各演替阶段土壤层次上均呈A〉B〉C〉D规律性分布的特点,退耕后1-10年,A、B 2层P含量的差异较大,C、D 2层受退耕时间的影响较小;退耕15-50年后,A、B、C、D 4个土层P含量变化的幅度相对较小。（3）在不同年限退耕地土壤各层次中,K的含量表现出和P同样的规律性,即A〉B〉C〉D的总体规律,退耕后1-30年间,C、D层K的含量随着退耕年限增加而波动式减小,而A、B层规律性不明显;退耕50年后,K的含量趋于稳定。

In order to manage and use vegetation resources more scientifically and rationally, the author based on the typical region of Shiyang River in Minqin County cultivated land as the research object, by analyzing the different restoration of distribution and the change of soil nutrient of recovery process of vegetation land in lower reaches of Shiyang River. The results showed that： （1） the content of N fertilizer in the soil with the increasing length of grain for the rising trend in a fluctuant way, but along with the deepening of the soil in the same duration of woodland decreased gradually, 1-10 years after the farmland, mostly for one year from the raw herbs and plants perennial root, the root shallow, the soil N content changed smaller; 15-30 years, 1 year raw herbs was gradually replaced by perennial herbs and shrubs, plant root depth up to 20-40 cm N content change relatively large amplitude; stabilised in 50 years, （2） P content in soil level five different stages were A〉B〉C〉D distribution regularity, the characteristics of 1-10 years after the farmland, the differences of the content of A, B layers P, C, D layers were affected by conversion of time smaller; grain for 15-50 years later, A, B, C, D amplitude phases soil P content changed. （3） In different fixed number of year at all levels, the content of K showed the same regularity as P, namely the general rule of A〉B〉C〉D, 1-30 years after returning farmland, the content of K C D layer increased with fluctuation decreased as the fixed number of year, and A, B layer regularity was not obvious. After farmland 50 years, content of the K tended to be stable.