Purpose

The objectives of this study were to evaluate the effects of long-term organic materials incorporation on the soil aggregate and density-based fractions, and associated soil carbon (C) and nitrogen (N) conversion in the rice fields.

Materials and methods

A long-term located experiment was conducted to study the effects of continuous application of organic materials (milk vetch, rice straw, and poultry manure) on the distribution characteristics of soil aggregate and density-based fraction, as well as its organic C and N, in rice fields. The soil aggregate was classified using the wet-sieving method. Light fraction (LF) and heavy fraction (HF) were classified according to density fractionation. Aggregate organic C (AC) and total N (AN), LF organic C (LFC) and N (LFN), and HF organic C and N concentrations were measured by using the Elementar Vario ISOTOPE elemental analyzer.

Results and discussion

Application of organic materials increased the aggregate mass proportion of 2–0.25 mm (by 4.9–12.6%) and 0.25–0.053 mm (by 27.5–40.7%) fraction and its AC and AN concentration. The soil aggregate particulate organic C and total N were greatly improved with organic materials application. Furthermore, organic material had more obvious effect on the soil C and N in the LF than HF, which improved the LF particulate mass proportions by 75.1–177.0%, LFC by 51.7–68.4%, and LFN by 14.2–111.2%, respectively. Poultry manure had the greatest effect on increasing the AC, LFC, AN, and LFN, followed by milk vetch and rice straw.

Conclusions

Milk vetch, rice straw, and poultry manure could effectively increase the soil intermediate aggregate and LF proportion, and stimulate the stabilization and fixation of C and N in rice fields. It is an effective agricultural practice by applying organic material to improve soil fertility and sustaining high crop productivity. The increases of intermediate aggregate and associated C and N may be the main factor for soil C and N sequestration under continual application of organic materials.

中文翻译：

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有机物施用对稻田物理分离土壤有机碳氮组分的影响

目的

这项研究的目的是评估长期有机物掺入对稻田土壤团聚体和密度分数以及相关土壤碳（C）和氮（N）转化的影响。

材料和方法

进行了长期定位实验，研究了连续施用有机材料（紫云英，稻草和家禽粪便）对土壤团聚体和密度基部分的分布特征及其有机碳和氮的影响。 ，在稻田里。使用湿筛法对土壤团聚体进行分类。根据密度分级将轻馏分（LF）和重馏分（HF）分类。使用Elementar Vario ISOTOPE元素分析仪测量了总有机碳（AC）和总N（AN），LF有机C（LFC）和N（LFN）以及HF有机C和N的浓度。

结果和讨论

有机材料的应用增加了总质量比例2-0.25 mm（增加4.9-12.6％）和0.25-0.053 mm（增加27.5-40.7％），以及其AC和AN浓度。施用有机材料可大大改善土壤团聚体中的有机碳和总氮。此外，有机物质对LF中土壤碳和氮的影响比HF更明显，分别使LF颗粒质量比提高了75.1–177.0％，LFC提高了51.7–68.4％，LFN降低了14.2–111.2％。家禽粪便对增加AC，LFC，AN和LFN的影响最大，其次是紫云英和稻草。

结论

紫云英，稻草和家禽粪便可以有效地增加土壤中间团聚体和LF的比例，并促进稻田中C和N的稳定和固定。通过应用有机材料来改善土壤肥力并维持高作物生产率，这是一种有效的农业实践。在持续施用有机材料的情况下，中间团聚体和相关碳氮的增加可能是土壤碳和氮固存的主要因素。