黄土丘陵沟壑区典型林地土壤微生物、酶活性和养分特征

Microbes, Enzyme Activities and Nutrient Characteristics of Rhizosphere and non-Rhizosphere Soils in Forests of Loess Hilly Region

通过对陕西吴起县黄土沟壑区退耕还林地不同林分(沙棘、刺槐、油松、小叶杨)根际与非根际土壤养分、酶活性和微生物特征进行研究,比较4种典型林分及退耕草地"根际效应"及根际对养分的截留效应,评价根际效应对土壤特性产生不同改良效果,为黄土沟壑区退耕地人工林科学选择造林树种提供理论支持。研究表明:1根际与非根际土壤中有机质含量、有效磷含量、碱解氮含量和速效钾含量表现出显著差异,有机质、有效磷、速效钾含量均呈现明显的根际聚集现象。2根际土壤微生物数量和土壤酶活性总体高于非根际,仅油松样地中过氧化氢酶活性和小叶杨样地中脲酶活性根际低于非根际。3根际土壤中脲酶活性与细菌和真菌数量相关性达到显著水平,过氧化氢酶活性与真菌相关性达到显著水平;有机质含量与细菌、放线菌数量和脲酶活性相关性达到显著水平;碱解氮、有效磷含量均与细菌、真菌数量和脲酶活性相关性达到显著水平。在非根际土壤中,土壤养分含量与土壤微生物、土壤酶活性的相关性明显降低。4从土壤肥力综合水平看,根际土壤肥力水平综合得分总体上大于非根际土壤,其中根际土壤中沙棘>小叶杨>油松>刺槐>草地。沙棘能大幅度提高土壤肥力,具有较好的土壤改良效果。

In this study, 4 types of forests （Hippophae rhamnoides, Pinustabuliformis, Robiniapseudoacacia and Populussimonii） were chosen to measure microbial abundance, enzyme activities and nutrient characteristics of rhizosphere and non-rhizosphere soils to make a comprehensive comparison of the soil fertility between rhizosphere and non-rhizosphere soils. The abundance of soil bacteria, fungi and actinomycetes, the activities of catalase, polyphenol oxidase and urease, soil organic matter （SOM）, total nitrogen （N）, total phosphorus （P）, total potassium （K）, alkai-hydrolyzadle N, available P and available K were determined and One-way analysis of variance and analysis of correlation were conducted. The results indicated that： 1） the differences of the contents of SOM, available P, alkali-hydrolyzadle N and available K between rhizosphere and non-rhizosphere soils were significant （P〈0.05）. SOM and available nutrients accumulated in rhizosphere soil. 2） Microbial abundance and enzyme activities of rhizosphere soil were generally higher than non-rhizosphere soil. With exceptions, catalase activity in Pinustabuliformis and and urease activity in Populussimonii were lower in rhizosphere soil than non-rhizosphere soil. 3） There was a significant correlation between urease activity and abundance of soil bacteria and fungi. There was also a significant correlation between eatalase activity and abundance of soil fungi. SOM was significantly correlated with the abundance of soil bacteria and aetinomyeetic, and urease activity. The soil available P and alkai-hydrolyzadle N contents were significantly correlated with urease activity, and the abundance of soil bacteria and fungi. In non-rhizosphere soil, the correlation of the contents of soil nutrients with soil microbial abundance and soil enzyme activities was lower than that in rhizosphere soil. 4） The comprehensive fertility level of the rhizosphere soil was higher than that of the non-rhizosphere soil. The fertility level of rhizosphere soil followed the order： Hippophae rhamnoides 〉 Populussimonii 〉 Pinustabuliformis 〉 Robiniapseudoacacia 〉 abandoned croplands. The growth of Hippophae rhamnoides can improve soil fertility more effectively than the other species. Hippophae rhamnoides is suitable for afforestation to help improve soil fertility and make contributions to revegetation.