Chemical attributes and microbial activity of soil cultivated with cassava under different cover crops

ABSTRACT Conservationist systems of crop management increases the amount of substrate, alters fertility and increases soil biological activity. The objective of this study was to evaluate the influence of soil management systems on the chemical attributes and microbial activity of soil under cassava crop. The experiment was set as completely randomized design in a factorial scheme of 2 x 3 x 2, being two systems of cultivation (minimum with only mown; minimum with mown and incorporation), three types of soil coverage (fallow; Crotalaria juncea L.; Canavalia ensiformis L.) and two soil depths (0-0.10 and 0.10-0.20 m), with four repetitions. The production of dry mass from cover crops, the soil chemical attributes and the soil microbial activity were evaluated. There were no differences between management systems, and the C. juncea cover crop presented superior dry mass production among the soil coverages. The concentrations of soil Ca and K were greater in the fallow coverage and C. juncea areas in the 0-0.10 m soil layer; however, these nutrients differ in the soil layer below (0.10-0.20 m). There were no differences for the basal respiration of soil microorganisms in both soil depths or among soil coverage, but the carbon from microbial biomass was superior in the most superficial soil layer where more substrate is available to soil microorganisms.

摘要：保护性作物管理体系可提升土壤底物含量、改良土壤肥力并增强土壤生物活性。本研究旨在探究土壤管理体系对木薯种植田土壤化学性状及微生物活性的影响。本实验采用完全随机设计，设置2×3×2因子方案：2种少耕体系（仅刈割型少耕、刈割后还田型少耕）、3种土壤覆盖处理（休耕；光叶猪屎豆（Crotalaria juncea L.）；直生刀豆（Canavalia ensiformis L.））、2个土层深度（0-0.10 m与0.10-0.20 m），每组设置4次重复。实验测定了覆盖作物的干物质产量、土壤化学性状及土壤微生物活性。结果显示，不同耕作体系间无显著差异；在所有土壤覆盖处理中，光叶猪屎豆的干物质产量最高。在0-0.10 m土层中，休耕与光叶猪屎豆覆盖处理的土壤钙（Ca）、钾（K）含量更高，但在下层土层（0.10-0.20 m）中，上述养分含量存在显著差异。不同土层深度及不同土壤覆盖处理下，土壤微生物基础呼吸速率均无显著差异，但浅层土壤的微生物生物量碳含量更高，因该土层可为土壤微生物提供更为充足的底物。