紫云英施用量对土壤活性有机碳和碳转化酶活性的影响

Effects of Chinese milk vetch (Astragalus sinicus L.) application rate on soil labile organic carbon and C-transformation enzyme activities

利用紫云英还田的定位试验研究不同紫云英施用量下土壤活性有机碳含量和碳转化酶活性的变化。试验包括对照、施用化肥和4个紫云英施用量(30、60、90和120 t·hm^(-2))处理。结果表明:与对照相比,施用化肥和紫云英均能够显著增加土壤活性有机碳(可溶性有机碳、热水提取态有机碳、微生物生物量碳和颗粒有机碳)含量,并且随着紫云英施用量的增加土壤活性有机碳含量显著增加。土壤碳转化酶活性的变化规律与土壤活性有机碳相同,其中施用化肥和紫云英较对照处理分别提高14%和24%~55%的纤维素酶活性、27%和45%~187%的蔗糖酶活性、42%和51%~165%的β-葡萄糖苷酶活性、11%和11%~24%的酚氧化酶活性以及16%和16%~27%的过氧化物酶活性。与对照相比,施用化肥对相对酶活性(酶活性与微生物生物量碳的比值)无显著影响;增加紫云英施用量能够显著增加相对蔗糖酶和相对β-葡萄糖苷酶活性,降低相对酚氧化酶活性和相对过氧化物酶活性。逐步回归分析表明土壤活性有机碳组分含量主要受纤维素酶、β-葡萄糖苷酶和酚氧化酶活性的影响。

The effects of Chinese milk vetch（ Astragalus sinicus L. hereafter vetch） application rate on changes of soil labile organic carbon fractions and C-transformation enzyme activities were studied through vetch returning site-specific experiment.The relationships between the contents of soil labile organic carbon fractions and enzyme activities were also investigated in this study. The experiment included control,application chemical fertilizer,and four vetch application rate（30,60,90 and 120 t·hm-2） treatments. The results showed that application of fertilizer or vetch both significantly increased the content of soil labile organic carbon（ dissolved organic carbon,hot-water extractable organic carbon,microbial biomass carbon,particulate organic carbon） compared with control treatment. The increase in vetch application rates led to significant increase of soil labile organic carbon content. The C-transformation enzyme activities showed similar trend with soil labile organic carbon. In comparison with control treatment,fertilizer and vetch application increased the acitvities of cellulose,invertase,β-glucosidase,phenol oxidase and peroxidase by 14% and 24% ~ 55%,27% and 45% ~ 187%,42% and 51% ~ 165%,11% and 11% ~ 24%,16% and 16% ~ 27%,respectively. Application of chemical fertilizer treatment had similar the relative enzyme activity（ the ratio of enzyme activity to microbial biomass carbon） compared with control treatment. The increase in vetch application rates significant increased the relative activities of invertase and β-glucosidase,but decreased the relative activities of phenol oxidase and peroxidase compared with control treatment. Stepwise multiple regression analysis showed that the activities of cellulose,β-glucosidase and phenol oxidase played the principal role in determining contents of soil labile organic carbon.