土壤活性有机质及其与土壤质量的关系

活性有机质是土壤的重要组成部分 ,主要包括溶解性有机碳、微生物生物量、轻组有机质。它在土壤中具有重要作用 :(1)可以表征土壤物质循环特征、评价土壤质量 ,可以作为土壤潜在生产力以及由土壤管理措施引起土壤有机质变化的早期指标 ;(2 )在养分周转中起重要作用 ,是植物的养分库 ,可以提供植物所需要的养分如氮、磷、硫等 ;(3)能稳定土壤结构 ,对维持团粒结构稳定性有重要作用。从土壤养分、土壤物理、化学性质方面讨论了活性有机质与土壤质量的关系。土壤中的溶解性有机碳、微生物生物量碳氮含量与土壤有机碳、全氮和碱解氮等物质的含量呈正相关。活性有机质受土壤质地、含水量、温度等因素影响 ,与土壤酸碱度、阳离子交换量等也有关。土壤微生物生物量碳和微生物量 C/有机碳比与土壤粘粒、粉粒含量呈正相关、与砂粒含量呈负相关

Active soil organic matter and its relationship with soil quality

Active soil organic matter (ASOM) is an important soil component, influencing dissolved organic carbon (DOC), microbial biomass (MB), and light fraction organic matter (LOM). In particular, soil organic matter (SOM) affects short-term nutrient turnover and is responsible for temporary stability of soil structure. ASOM is a major component of biochemical cycles of nutrient elements such as N, P, S, and both its quality and quantity reflect and control primary productivity. ASOM has been proposed as a sensitive indicator of early changes in SOM under different management practices such as tillage, straw incorporation, fire, clear-cutting, or manure application. Because of its dual roles as a pool of labile nutrients and as the agent of decomposition of organic materials in soil, MB may be a sensitive indicator of changes in ASOM. This pool is important since it serves as a readily decomposable substrate for soil microorganisms, a short-term reservoir of plant nutrients, and fragments become the centre for formation of water-stable aggregates. Increases in organic matter quantity and especially quality can resulted in increased N mineralization potential and greatly increased aggregate stability. ASOM was evaluated as an index of soil quality (SQ). In this paper, the authors discuss on the relationship between soil nutrients, physical and chemical properties and SQ. The quantity and quality of ASOM were found to be influenced by soil factors such as texture, water content, temperature, cation exchange capacity, and pH value. A very significant positive correlation was found between the concentrations of DOC, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and the concentrations of soil organic carbon, total nitrogen and available nitrogen. MBC and ratio of MBC to DOC were positively correlated with soil clay and silt contents, and negatively correlated with soil sand content.