秸秆还田的土壤酶效应初探

Effects of straw returning on soil enzyme activity

【目的】研究不同秸秆还田模式对土壤有机碳含量及酶活性的影响,探讨秸秆还田适宜模式。【方法】试验地位于陕西关中平原的三原县,在小麦-夏玉米一年二熟轮作模式下,采用田间试验,进行2因素3水平试验设计,分别设置小麦、玉米秸秆还田2个因素,每个因素下设3个水平（小麦秸秆还田：小麦秸秆高留茬覆盖还田模式、小麦秸秆粉碎还田模式和小麦秸秆不还田模式;玉米秸秆还田：玉米秸秆粉碎还田模式、玉米秸秆粉碎深松还田模式和玉米秸秆不还田模式）,共组成9种模式,分析不同秸秆还田模式下5~30和30~60cm土层土壤有机碳、易氧化碳含量及β-葡萄糖苷酶、FDA水解酶、蔗糖酶、多酚氧化酶、碱性磷酸酶、脱氢酶活性和总体酶活性（TEI）的变化特征。【结果】与对照（玉米秸秆不还田＋小麦秸秆不还田）相比,8种秸秆还田模式有机碳、易氧化碳含量均明显增加,其中小麦秸秆不还田＋玉米秸秆粉碎还田模式5~30cm土层土壤有机碳含量增幅最大,达到34.72%;小麦秸秆粉碎还田＋玉米秸秆不还田模式5~30cm土层土壤易氧化碳含量增幅最大,达到27.02%。与对照相比,秸秆还田模式总体上提高了5~60cm土层β-葡萄糖苷酶、FDA水解酶、蔗糖酶、多酚氧化酶、碱性磷酸酶和脱氢酶6种酶的活性,除脱氢酶外差异均达到了显著水平;在5~60cm土层,所有秸秆还田模式TEI均高于对照,总体上差异达显著水平,其中小麦秸秆不还田＋玉米秸秆粉碎还田模式5~30cm土层TEI增幅最大,达到40.23%。土壤FDA水解酶、蔗糖酶和TEI可在一定程度上用于表征秸秆还田模式的优劣。【结论】综合考虑可知,小麦秸秆不还田＋玉米秸秆粉碎还田模式是陕西关中地区适宜的秸秆还田模式。

Abstract： [Objective] The effects of returning different straws in field scale on soil organic carbon （SOC） and soil enzyme activity were studied to explore the optimal straw returning pattern. [Method] The field experiments were conducted in Sanyuan County,Guangzhong Plain with 9 straw returning treatments in wheat-maize cropping system. Wheat straw returning options were wheat straw retention, smashed wheat straw mulching, and no wheat straw returning, and maize straw returning options included smashed maize straw mulching, smashed maize straw returning to deep soil, and no maize straw returning. The char- acteristics of SOC, soil readily oxidizable organic carbon, soil 13-glucosidase, FDA hydrolase,invertase, poly- phenol oxidase,phosphatase,dehydrogenase,total enzyme activity index （TEI） in soil layers of 5--30 cmand 30--60 cm were analyzed, respectively. [Result] Compared with control （CK, no straw returning）, all straw returning treatments increased SOC and soil readily oxidizable organic carbon significantly. The lar- gest increase of SOC （34.72%） was obtained with no wheat returning~ smashed maize straw mulching （WN＋MC） ,and the largest increase of soil readily oxidizable organic carbon （27.02~） was obtained with smashed wheat straw mulching-t-no maize straw returning （WC-b-MN） in soil layer of 5--30 cm. Straw re- turning treatments significantly increased activities of all soil enzymes except dehydrogenase in soil layer of 5--60 cm. Compared with CK,all straw returning treatments increased TEI significantly, while the largest increase of TEI （40.23~） appeared in no wheat returning＋smashed maize straw mulching （WN＋MC） in soil layer of 5--30 cm. FDA hydrolase,invertase, and TEI could be used to assess the effects of straw. [Conclusion] WN-t-MC was the optimal straw returning pattern in Guanzhong area of Shaanxi.