压砂地持续利用对土壤的影响

Effects of the Sustainable Use of Gravel-mulched Land on Soil

以宁夏中部干旱区压砂地为研究对象,分析压砂地持续利用对土壤质量的影响。结果表明,随着压砂地利用年限的增加土壤肥力呈逐年下降的趋势,持续压砂利用15a后,土壤有机质、全氮、碱解氮质量分数分别比对照下降57.43%、46.56%、48.89%。压砂地土壤微生物量碳、氮随着压砂利用年限的延长整体呈下降趋势,土壤微生物生物量碳/氮值低于对照;持续压砂利用后,土壤微生物群落中细菌、真菌、放线菌的数量均显著降低,压砂改变了土壤微生物群落结构组成。Biolog ECO板的平均颜色变化率(AWCD)随培养时间的增加呈上升趋势。压砂初期土壤微生物的碳源利用能力和微生物的功能多样性显著增加,但持续利用后期与对照无明显差异。压砂地不同土层土壤微生物类群对土壤碳源基质利用类型和利用能力存在差异,0~20cm土壤微生物群落对羧酸类化合物利用能力较强,20~40cm土壤微生物群落以碳水化合物利用类群为主。持续压砂影响土壤微生物的结构与功能,限制土壤养分的有效供给,可能是压砂地难以持续利用的主要因素。

The effects of the grave-mulched land^s sustainable usage on soil quality were studied in the middle arid region of Ningxia. the results showed： The fertility of soil had a declining trend along with the growth of the grave mulched land usage year, and the content of soil organic matter, total nitrogen, available nitrogen dropped 57.43%, 46. 56%, 48.89% respectively than CK（the farmland） when the land was used for 15 years. With the usage years extended, the microbial biomass carbon and nitrogen in grave-mulched land showed a declining tread in general, and the microbial carbon/ nitrogen ratio was lower than CK;after the sustainable usage, the quantity of the fungus, bacteria and actinomycetes significantly decreased, showing the gravel-mulched land changed the soil microbial community structure. The average well color development （AWCD） of the BIOLOG-ECO plate was increased along with the growth of the culture time. In the very beginning of sand-putting, the carbon resource utilization capacity and the microbial functional diversiw significantly increased, but there＇s no apparent difference with CK after sustainable usage. The microorganism group＇s carbon resourceutilization patter and capacity in different soil layers had some differences, showing the microorgan- isms in 0--20 cm had a stronger capacity in using the carboxy compound, and the mainly carbon re- source utilization patter in 20--40 em was carbon compound. The grave-mulched land＇s sustainable usage affected the microbial community structure and function, inhibited the effective supply of the soil nutrients, which maybe the factors that made the grave-mulched land hard to be sustainable used.