荒漠草原区土壤粒径组成对柠条根际土壤微生物数量及酶活性的影响

柠条(Caragana korshinskii)是荒漠草原区主要的造林绿化树种,研究其根际土壤微生物和酶活性与不同土壤类型土壤粒径组成的关系有重要意义,然而土壤粒径对荒漠草原柠条根际土壤微生物数量和酶活性的影响知之甚少,探讨土壤颗粒组分与微生物数量、土壤酶活性之间的关系,以及土壤颗粒组成对荒漠草原区固沙灌木植物柠条根际土壤微生物数量及酶活性的影响,可为揭示荒漠草原土壤退化及生态修复提供参考。以宁夏荒漠草原区土壤粒径组成差异显著的灰钙土、红黏土、风沙土环境下栽植的柠条为研究对象,研究不同土壤颗粒组成对根际土壤微生物数量及酶活性的相互关系与影响。结果表明:土壤微生物的数量表现为细菌放线菌真菌。根际土壤中的细菌、真菌数量显著高于非根际,且在3种不同类型的土壤中随着细砂粒的增多,真菌和放线菌数量逐渐降低,而细菌数量呈先增大后减小的趋势;根际与非根际土壤的蔗糖酶、碱性磷酸酶及过氧化氢酶活性均呈现出灰钙土红黏土风沙土的趋势,红黏土根际土壤中的脲酶活性显著高于灰钙土与风沙土;除过氧化氢酶外,土壤酶活性表现为根际高于非根际,在3种不同类型的土壤中随着细砂含量的增加,土壤酶活性均呈递减趋势。土壤颗粒组成与微生物数量之间没有明显的相关性,而与土壤酶活性之间显著相关,土壤酶活性与黏粒、粉粒呈正相关,与细砂、中砂呈负相关关系,根际土壤中酶活性更高,能够为植物及微生物提供更多的营养。

Effects of soil particle size on enzyme activities and the amount of soil microorganism in rhizosphere of Caragana korshinskii in desert steppe

Caragana korshinskii is the main afforestation tree species in desert steppe, it is important to study the relationship between microorganisms and enzymes in rhizosphere soil and soil particle size composition. Soil types affect enzyme activities and the amount of microorganism in rhizosphere soil, soil particle size in different soil types is different, however, little is known about how soil particle size affect on enzyme activities and the amount of soil microorganism in rhizosphere of Caragana korshinskii planted in desert steppe. In this study, soil enzyme activities and the amount of soil microorganism in rhizosphere and non-rhizosphere soil in three soil types were analyzed, as well as soil particle size of sierozem, red clay soils, and aeolian sandy soils in Yanchi country of Ningxia. The results showed that the amount of bacteria in rhizosphere soil was significantly higher than that in non-rhizosphere soil, and the amount of fungi increased with the increase of fine sand grains in three soil types. The activities of sucrase, alkaline phosphatase, and catalase in rhizosphere and non-rhizosphere soil presented the tendency of sierozem > red clay soils > aeolian sand soils. The urease activity in red clay soils of rhizosphere was significantly higher than that in sierozem and aeolian sand soils. The amount of fungi and actinomycetes decreased gradually, while the amount of bacteria increased firstly and then decreased. The amount of bacteria and fungi were more abundant than bulk soil. With the increasing of fine sand content, the amount of fungi and actinomycetes gradually decreased while the amount of bacteria increased and then decreased. Soil enzyme activity in rhizosphere exceeded bulk except catalase. With the increasing of fine sand content, soil enzyme activity gradually decreased. There was no significant correlation between soil particle size and the amount of soil microorganism and soil enzyme activity presented a positive correlation with clay and silt sand but it negatively correlated with fine sand and medium sand, rhizosphere soil has higher enzyme activity and could provide more nutrients for plants and microorganisms.