Effects of Earthworms on Nitrogen Cycling Processes and Decomposer Community Structure in Organic-based and Conventional Agroecosystems

蚯蚓影响许多基本的土壤过程，但总的来说， 这些重要无脊椎动物对生态系统的影响 过程知之甚少。 Stinner Blair和Edwards医生 表明蚯蚓是影响结构的关键生物 和功能的分解者社区和土壤过程在许多 陆地生态系统，包括农业生态系统。 本研究 探讨蚯蚓作为分解调节剂的重要性 群落结构、有机质分解和氮循环 在基于有机或无机来源的农业生态系统中 营养素蚯蚓种群在外地围栏将 在三个实验农业生态系统中进行操作，其中N是 主要作为i）豆类来源的N，ii）动物粪肥N， 或iii）无机肥料。 有机质分解与氮素 循环过程将被用作集成变量，以评估 生物活动对农业生态系统功能的影响。 将对以下影响进行量化：a）土壤微生物 数量和活动，B）其他土壤种群 （c）有机物的分解和 土壤有机质组分，d）土壤物理特性， e）将N分配到选定的地上和地下库中 （植物生物量N、凋落物N、SOM、活性（微生物）土壤N、 缓慢/被动土壤N，可提取的土壤N）;和f）速率和 从15 N标记的植物残留物中释放N的模式， 恢复在选定的土壤池和植物吸收的N。 这种方法提供了一个独特的，全面的视角， 蚯蚓在影响生态系统一级进程方面的重要性。 研究蚯蚓在基于有机物的系统中的作用 输入或无机氮将提供数据的相对影响， 蚯蚓在不同C或N水平下的系统 限制. 蚯蚓的交互作用分析 土壤生物区系和过程的有机物质输入将 为影响氮素利用的基本机制提供了新的见解 在陆地生态系统的总体效率和养护方面。 这项研究也将大大有助于了解 蚯蚓对氮素动态的调节 农业生态系统和传统的无机肥 农业生态系统 这项研究的支持和设施是 非常出色。

Earthworms affect many basic soil processes, but the overall impact of these important invertebrates on ecosystem-level processes are poorly understood. Drs. Stinner, Blair and Edwards suggest that earthworms are key organisms affecting the structure and function of decomposer communities and soil processes in many terrestrial ecosystems, including agroecosystems. This research examines the importance of earthworms as regulators of decomposer community structure, organic matter decomposition and N cycling in agroecosystems based on organic or inorganic sources of nutrients. Earthworm populations in field enclosures will be manipulated in three experimental agroecosystems where N is supplied primarily as i) legume-derived N, ii) animal manure N, or iii) inorganic fertilizer. Organic matter decomposition and N cycling processes will be used as integrating variables to assess the effects of earthworm activity on agroecosystem function. The following effects will be quantified: a) soil microbial numbers and activity, b) populations of other soil invertebrates, c) organic matter decomposition and changes in soil organic matter fractions, d) soil physical characteristics, e) partitions of N into selected above- and below-ground pools (plant biomass N, litter N, SOM , active (microbial) soil N, slow/passive soil N, extractable soil N); and f) rates and patterns of release of N from 15N-labelled plant residues, recovery in selected soil pools and plant uptake of N. This approach provides a unique, holistic perspective of the importance of earthworms in affecting ecosystem-level processes. Examining the effects of earthworms in systems based on organic inputs or inorganic N will provide data on the relative impact of earthworms in systems under different degrees of C or N limitation. Analysis of the interactive effects of earthworms and organic matter inputs on soil biota and processes will provide new insights into the basic mechanisms affecting N use efficiency and conservation in terrestrial ecosystems in general. The research will also contribute greatly to an understanding of regulation by earthworms of N dynamics in both organic N-based agroecosystems and conventional inorganically fertilized agroecosystems. The support and facilities for this research are outstanding.