不同栽培模式下豫北沙化土壤微生物量和酶活性

Microbial biomass and enzymatic activity in sandy soils of northern Henan Province with different alfalfa and awnless brome cultivating patterns

通过连续6 a定位试验,以沙化裸地为对照,研究紫花苜蓿Medicago sativa单播、无芒雀麦Bromus inermis单播、紫花苜蓿/无芒雀麦混播3种栽培模式对豫北沙化地区土壤微生物量碳、氮、磷以及土壤酶的影响,利用回归分析和通径分析对二者的关系进行研究。结果表明:与沙化裸地相比, 0～40 cm土层3种栽培模式下土壤微生物量碳、氮、磷质量分数和土壤酶活性均不同程度增加,从大到小依次为紫花苜蓿/无芒雀麦混播、紫花苜蓿单播和无芒雀麦单播,且土壤微生物量碳、氮、磷质量分数和土壤酶活性均随土层的加深而降低,呈现表聚性特征。相关性分析表明:土壤微生物量碳、氮、磷与土壤7种酶均呈显著(P<0.05)或极显著(P<0.01)相关;通径分析进一步表明:土壤酶对土壤微生物量碳的直接贡献效应从大到小依次为脲酶、淀粉酶、β-葡萄糖苷酶、蔗糖酶和蛋白酶,对土壤微生物量氮的直接贡献效应从大到小依次为脲酶、蔗糖酶、β-葡萄糖苷酶和碱性磷酸酶,对土壤微生物量磷的直接贡献效应从大到小依次为蔗糖酶、碱性磷酸酶、β-葡萄糖苷酶、过氧化氢酶和淀粉酶。由此认为,相对于沙化裸地,豫北地区经6 a人工草地建植,土壤微生物量碳、氮、磷以及土壤酶活性有效提高,土壤主要生物学性状优化,以紫花苜蓿/无芒雀麦混播为最佳的栽培模式。

In order to investigate the effects of different cultivating patterns on m icrobial content and related enzyme activities in sandy soils of northern Henan Province, through six consecutive years of positioning tests in northern Henan Province, compared with sandy bare land, the effects of three kinds of cultivating patterns(alfalfa single-sowing, awnless brome single-sowing, and alfalfa/awnless brome mixed-sowing) on soil microbial biomass carbon(MBC), nitrogen(N), phosphorus(P), and soil enzymes were studied. Both a regression analysis and a path analysis were used. Results showed that compared with sandy bare land, the contents of soil MBC, N, P, and enzymes for the three kinds of cultivating patterns in the 0 to 40 cm soil layer increased in the order of alfalfa/awnless brome mixed-sowing>alfalfa single-sowing>awnless brome single-sowing. The contents decreased with lower soil layers, that is, surface aggregation features were present. The correlation analysis showed that the presence of soil MBC, N, P, and seven kinds of soil enzymes were significant(P<0.05) or highly significant(P<0.01) with r value ranging from 0.744-0.980. The path analysis further showed that the direct contribution effect of soil enzymes from large to small on soil MBC was urease>amylase>beta-glycosidase>sucrase >protease, on soil microbial biomass N was urease>sucrase>beta-glycosidase>alkaline phosphatase, and on soil microbial biomass P was sucrase >beta-glycosidase >alkaline phosphatase >catalase >amylase. In conclusion, after six years of artificially planted grasslands in northern Henan Province, compared to sandy bare land, the contents of soil MBC, N, P, and the activities of soil enzymes greatly improved optimizing the main physical and chemical soil properties with the alfalfa/awnless brome mixed-sowing being the best cultivating pattern.[Ch, 1 fig. 6 tab. 20 ref.].