长期施肥对不同深度稻田土壤碳氮水解酶活性的影响特征

Effects of Long-term Fertilization on Enzyme Activities in Profile of Paddy Soil Profiles

与稻田土壤碳周转密切相关的酶活性是评价土壤肥力和肥料管理的重要指标.本研究选取秸秆还田(ST)、化肥(NPK)和不施肥(CK)的长期定位试验田,以10 cm的间距分段采集土壤剖面0~40 cm范围内的新鲜土样,利用96微孔酶标板荧光分析法,测定参与土壤碳氮转化过程关键酶β-1,4-葡萄糖苷酶(BG)和β-1,4-N-乙酰氨基葡萄糖苷酶(NAG)活性,探讨不同施肥措施对不同深层土壤酶活的影响.结果表明,相比不施肥的土壤,施用化肥和秸秆土壤的BG酶活性分别提高了35%~118%和55%~342%;NAG酶活性分别提高了9%~30%和102%~484%.同时,随着土层深度的增加,土壤酶活性逐渐降低,0~20 cm深层土壤酶活性显著高于20~40 cm深层土壤.在不同施肥措施中秸秆还田可高程度影响稻田深层土壤.RDA分析表明土壤碳氮含量主要与0~20 cm的土壤酶活性有显著的正相关关系,与20~40 cm的土壤酶活性呈负相关关系.综上所述,随着土壤深度增加土壤微生物量和土壤酶活性显著降低.长期施肥显著提高了不同深层土壤生物量和土壤酶活性,其中秸秆还田作用尤为突出.因此,合理的秸杆还田有利于改善稻田深层土壤肥力,优化农田土壤养分循环,为作物生长提供良好的土壤环境.

The enzyme activity, which is closely related to soil material cycling （mineralization, transformation, etc. ） , can reflect soil quality and nutrient status. In order to explore the effect of long-term fertilization on the enzyme activity in paddy soil profile （0-40 cm） , soils with organic fertilizer and inorganic fertilizer, and non-fertilized soils were selected, and the carbon and nitrogen contents, and the activities offl-1,4-glucosidase （BG） , and fl-1,4-N-acetylglucosaminidase （NAG） in 10cm depths of soil were analyzed. The results showed that the activities of BG and NAG in the soils treated with inorganic fertilizer and organic fertilizer increased by 0.73- 47.87 nmol·（g·h）-1 and 1.33-128.81 nmol·（g·h）-1, and 0.19-9.72 nmol·（g·h）-1 and 0.92-57.66 nmol·（g·h）-1, respectively, compared to those for non-fertilized soil. Soil enzyme activity decreased with increasing soil depth. Soil enzyme activity in soil from 0-20 cm was significantly higher than that of soil from 20-40 cm. Soil enzyme activities were significantly affected by long term fertilization at different soil depths. RDA analysis showed that soil carbon and nitrogen contents had significant positive relationships with the activities of BG and NAG in the 0-20 cm soil profiles, however, negative relationships were observed in the 20-40 cm soil profiles. The long-term application of organic fertilizer significantly increased soil biomass and enzyme activity, both of which decreased with the increase in soil depth. Long-term fertilization could increase soil nutrient contents, microbial biomass, and extracellularenzyme activities, which has important theoretical significance for optimizing farmland fertilizer management and improving soil productivity.