Soil erosion significantly decreases aggregate-associated OC and N in agricultural soils of Northeast China

• Published in: Agriculture, ecosystems & environment Vol. 323; p. 107677
• Main Authors: Li, Haiqiang, Zhu, Hansong, Liang, Chenglong, Wei, Xiaorong, Yao, Yufei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2022
• Subjects: Agricultural erosion; Converting forest to agricultural land; Nitrogen in aggregates; Organic carbon in aggregates; Organic carbon in aggregates; Converting forest to agricultural land; Agricultural erosion; Nitrogen in aggregates
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2021.107677

Cultivation after the converting natural ecosystems to agricultural land is often accompanied by accelerated soil erosion. To better understand how land-use conversion and agricultural erosion separately affect aggregate-associated nitrogen (N) and organic carbon (OC), we examined the responses of aggregate-associated N and OC to both the converting forest to agricultural land and erosion in the agricultural region of Northeast China. Non-erosion sites in forest and agricultural land converted from forestland 60 years ago were selected to address the effects of land-use change. The sites with various erosion intensities in an eroding area of sloping cropland (i.e., non-erosion, light erosion, moderate erosion and heavy erosion) were selected to compare the effects of the erosion intensity. The measured soil metrics included the soil bulk density, water-stable aggregates, and aggregate-associated OC and N along 0–70 cm soil profiles. Converting forest to agricultural land did not significantly influence the OC and N concentrations in each aggregate, while the land-use change significantly reduced the OC and N stocks in macroaggregates but increased them in microaggregates and silt+clay fraction. However, erosion significantly decreased the OC and N concentrations and stocks in each aggregate. The changes in the OC and N stocks in aggregates were mainly due to the depletion of soil aggregates in responding to the conversion of forest to agricultural land but due to decreases in OC and N concentrations in aggregates in responding to soil erosion. Our results indicated that the effects of erosion on aggregate-associated OC and N were greater compared with the effects of converting forest to agricultural land in this Mollisol region. •Land-use change didn’t significantly affect OC and N concentrations in aggregates.•Erosion decreased OC and N concentrations in aggregates.•OC and N stocks in aggregates were determined by their concentrations during erosion.•OC and N stocks in aggregates were dominated by aggregates mass following land-use change.