Sun Lipeng, Jing Hang, Wang Guoliang, Liu Guobin
Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi, China.
PeerJ. 2018 Jun 25;6:e5039. doi: 10.7717/peerj.5039. eCollection 2018.
Glomalin-related soil protein (GRSP) and soil organic carbon (SOC) contribute to the formation and stability of soil aggregates, but the mechanism by which global atmospheric nitrogen (N) deposition changes soil aggregate stability by altering the distribution of GRSP and SOC in different aggregate fractions remains unknown.
We used a gradient N addition (0-9 g N m y) in forest for two years in northeast China and then examined the changes in SOC contents, total GRSP (T-GRSP), and easily extractable GRSP (EE-GRSP) contents in three soil aggregate fractions (macro-aggregate: >250 μm, micro-aggregate: 250-53 μm, and fine material: <53 μm) and their relationship with aggregate stability.
(1) The soil was dominated by macro-aggregates. Short term N addition had no significant effect on mean weight diameter (MWD) and geometric mean diameter (GMD). (2) GRSP varied among aggregate fractions, and N addition had different effects on the distribution of GRSP in aggregate fractions. The EE-GRSP content in the macro-aggregates increased initially and then decreased with increasing N addition levels, having a peak value of 0.480 mg g at 6 g N m y. The micro-aggregates had the lowest EE-GRSP content (0.148 mg g) at 6 g N m y. Furthermore, the T-GRSP content significantly increased in the aggregate fractions with the N addition levels. (3) The macro-aggregate had the highest SOC content, followed by the micro-aggregate and the fine material had the lowest SOC content. N addition significantly increased the SOC content in all the aggregate fractions. (4) GRSP and SOC contents were not significantly correlated with MWD.
Glomalin-related soil protein and SOC contents increased by N addition, but this increase did not enhance aggregate stability in short term, and the improvement of stability might depend on binding agents and incubation time.
球囊霉素相关土壤蛋白（GRSP）和土壤有机碳（SOC）有助于土壤团聚体的形成和稳定性，但全球大气氮（N）沉降通过改变GRSP和SOC在不同团聚体组分中的分布来改变土壤团聚体稳定性的机制尚不清楚。
我们在中国东北的森林中进行了两年的梯度施氮（0-9 g N m² y⁻¹），然后检测了三个土壤团聚体组分（大团聚体：>250 μm，微团聚体：250-53 μm，细颗粒：<53 μm）中SOC含量、总GRSP（T-GRSP）和易提取GRSP（EE-GRSP）含量的变化及其与团聚体稳定性的关系。
（1）土壤以大团聚体为主。短期施氮对平均重量直径（MWD）和几何平均直径（GMD）没有显著影响。（2）GRSP在团聚体组分间存在差异，施氮对GRSP在团聚体组分中的分布有不同影响。大团聚体中EE-GRSP含量随施氮水平增加先增加后降低，在6 g N m² y⁻¹时达到峰值0.480 mg g⁻¹。微团聚体在6 g N m² y⁻¹时EE-GRSP含量最低（0.148 mg g⁻¹）。此外，随着施氮水平增加，团聚体组分中T-GRSP含量显著增加。（3）大团聚体中SOC含量最高，其次是微团聚体，细颗粒中SOC含量最低。施氮显著增加了所有团聚体组分中的SOC含量。（4）GRSP和SOC含量与MWD没有显著相关性。
施氮增加了球囊霉素相关土壤蛋白和SOC含量，但短期内这种增加并未提高团聚体稳定性，稳定性的提高可能取决于粘结剂和培养时间。
