How the chemical composition and heterogeneity of crop residue mixtures decomposing at the soil surface affects C and N mineralization
How the chemical composition and heterogeneity of crop residue mixtures decomposing at the soil surface affects C and N mineralization
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DOI：
10.1016/j.soilbio.2014.07.014
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发表时间：
2014-11-01
影响因子：
9.7
通讯作者：
Giacomini, Sandro Jose
中科院分区：
文献类型：
--
作者：
Redin, Marciel;Recous, Sylyie;Giacomini, Sandro Jose
植物凋落物特性对土壤和土壤表面分解的影响对于农业生态系统养分和碳（C）的充分管理至关重要。然而，了解残留物的混合物的影响，这实际上是在农业中遇到的最常见的情况下，仍然知之甚少的耕作土壤。因此，我们分析了25种植物（主要作物和覆盖作物），在亚热带条件下的农业系统的代表，随后的C和氮（N）矿化的混合叶和茎凋落物的影响。我们的特点是叶，茎和混合物的化学和确定的异质性的混合物，使用高尔的相似系数。我们在25摄氏度的桑迪壤土表面培养了120天的作物残体，并连续测量了C和N的矿化。这25种混合物代表了广泛的化学性质和异质性。碳矿化和土壤氮积累的显着差异明显区分作物科（特别是禾本科物种与豆科物种），和植物部位（茎与叶）。C矿化的观测值和预期值之间的差异很低或为零，这主要表明混合的叠加效应。只有7个物种存在显着的协同效应，导致平均额外9%的C矿化。对于N，仅在平均N含量高且化学异质性高的豆科混合物中观察到拮抗效应。我们的结论是，混合物的分解似乎主要由其平均化学组成，并在较小程度上由其化学异质性控制。在这些情况下，N的混合物中的可用性似乎增加了微生物N的固定，减少了矿物N在土壤中的净积累。(C)2014爱思唯尔有限公司版权所有。
The effects of plant litter characteristics on its decomposition in soil or at the soil surface is of primary importance for adequate management of nutrients and carbon (C) in agro-ecosystems. However, understanding the influence of mixtures of residues, which is actually the most common situation encountered in agriculture, is still poorly known in cultivated soils. Therefore we analyzed the effect of mixing leaf and stem litters from 25 species of plants (main crops and cover crops), representative of agricultural systems in subtropical conditions, on subsequent C and nitrogen (N) mineralization. We characterized the chemistry of leaves, stems and mixtures and determined the heterogeneity of the mixtures using Gower's similarity coefficient. We incubated crop residues at the surface of a sandy loam soil at 25 degrees C over 120 days and continuously measured the mineralization of C and N. The 25 mixtures represented a wide range of chemical qualities and heterogeneity. Significant differences in C mineralization and soil N accumulation clearly differentiated crop families (notably Poaceae species vs. Fabaceae species), and plant parts (stems vs. leaves). The differences between observed and expected values for C mineralization were low or nil, indicating mostly an additive effect of mixing. Significant synergetic effects existed for only 7 species and resulted in an average additional 9% C mineralized. For N, an antagonistic effect was observed only with Fabaceae mixtures having high average N content and high chemical heterogeneity. We concluded that the decomposition of mixtures appeared mainly controlled by their average chemical composition and to a less degree by their chemical heterogeneity. In these cases, the availability of N in the mixtures appeared to increase the microbial N immobilization, reducing the net accumulation of mineral N in the soil. (C) 2014 Elsevier Ltd. All rights reserved.