秸秆还田是有效利用秸秆资源的重要途径, 能够提高土壤养分含量、调节土壤微生物的群落结构和多样性, 但目前还缺乏不同秸秆还田方式对新疆沙化土壤肥力和微生物多样性影响的系统报道。为探索新疆沙化土壤肥力可持续提升模式, 于2010—2012年在和田风沙土土壤上设置秸秆直接还田(NPKS)、过腹还田(NPKM, 15.0 thm2)和炭化还田(NPKB1, 2.5 thm2; NPKB2, 15.0 thm2)定位试验, 研究不同秸秆还田处理对和田风沙土土壤养分、微生物数量、土壤酶活性和Biolog碳源利用的影响。结果表明: 1)与单施化肥(NPK)相比, 不同秸秆还田方式均能显著提高风沙土土壤养分含量, 其中NPKM处理效果最好, 其次是NPKB2处理, NPKS和NPKB1处理分别为第3和第4。2)不同秸秆还田方式对土壤微生物数量影响差异显著, 均增加了土壤中细菌、放线菌和生理菌群的数量, 与NPK处理相比, 细菌数量NPKB2处理最高, 放线菌数量NPKM处理最高, 分别显著提高了413.16%和574.19%。但NPKB1和NPKB2处理对生理菌群数量的提升效果好于NPKS处理和NPKM处理。土壤酶活性, 不同秸秆还田方式总体好于NPK处理, NPKM处理的提升效果最好。3)Biolog碳源利用分析表明不同秸秆还田方式均能提高风沙土土壤微生物活性和丰富度指数。主成分分析表明, 不同秸秆还田方式土壤微生物群落明显不同, 起分异作用的碳源主要为羧酸类和糖类。聚类分析显示NPKB2和NPKM处理之间、NPKB1和NPKS处理之间土壤微生物功能相似。由此可以看出, 不同秸秆还田方式均能显著提高和田沙化土壤微生物活性和功能多样性, 但不同方式的增效不同。从3年定位试验结果看, 秸秆过腹还田和炭化还田的效果较好, 秸秆直接粉碎还田有增加土传病害的风险。该结果将为南疆沙化土壤肥力可持续提升提供一定的理论指导。
Straw incorporation to soil is an effective way to utilize plant straw resource. It improves soil fertility and regulates soil microbial community structure and diversity. Despite this, there are few reports on the effect of different straw incorporation modes on soil fertility and microbial diversity in sandy soils in Xinjiang. Field trials were conducted with direct straw incorporation (NPKS), abdomen-digested straw incorporation (sheep manure application, NPKM, 15.0 thm2) and carbonized straw incorporation (biochar application, NPKB1, 2.5 thm2 and NPKB2, 15.0 thm2) to the field to evaluate the effects of different straw incorporation modes on soil nutrient, microbial quantity, enzyme activity and microbial carbon utilization in sandy soils in southern Xinjiang during the period of 2010–2012. The results showed that: 1) Compare with the control (chemical fertilization, NPK) treatment, different straw incorporation modes significantly improved soil nutrient of sandy soils. NPKM treatment was the best, followed by NPKB2 treatment, NPKS treatment and then NPKB1 treatment. 2) Different straw incorporation modes had considerable effect on soil microbial population. The treatments increased the populations of soil bacteria and actinomycete and the number of physiological groups of bacterial. Compared with NPK treatment, the population of bacteria was highest under NPKB2 treatment while the population of actinomycete was highest under NPKM treatment; increasing significantly by 413.16% and 574.19%, respectively. The number of physiological groups of bacterial under NPKB1 and NPKB2 treatments was higher than that under NPKS treatment. Soil enzymes activities of different straw incorporation modes were generally higher than that under NPK treatment, and NPKM treatment had the best effect on soil enzymes activities. 3) Biolog carbon resources utilization analysis showed that different straw incorporation modes improved soil microbial activity and richness index. Principal component analysis showed that obvious differences in soil microbial community among different straw incorporation modes. The differences in carbon resources utilization were mostly caused by carboxylic acids and carbohydrates. Cluster analysis showed that between NPKB2 and NPKM, and between NPKB1 and NPKS had similar microbial functions. The results indicated that different straw incorporation modes significantly improved soil microbial activity and functional diversity in sandy soils. However, the effect of soil improvement was different for different modes. The 3-years (2010–2012) experimental results suggested that abdomen-digested straw incorporation and carbonized straw incorporation to the field had better effects, while direct straw incorporation to the field increased the risk of soil borne diseases. The results added to the existing theoretical guidance on establishing modern eco-efficient fertilization modes in sandy soils in southern Xinjiang.