Erosion and covered zones altered by surface coverage effects on soil nitrogen and carbon loss from an agricultural slope under laboratory-simulated rainfall events

Authors: WANG, LINHUA - South China Botanical Garden; YEN, HAW - Texas A&M University; Huang, Chi Hua; WANG, YAFENG - Chinese Academy Of Sciences

Submitted to: International Soil and Water Conservation Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2022
Publication Date: 1/19/2022
Citation: Wang, L., Yen, H., Huang, C., Wang, Y. 2022. Erosion and covered zones altered by surface coverage effects on soil nitrogen and carbon loss from an agricultural slope under laboratory-simulated rainfall events. International Soil and Water Conservation Research. 10(3):382-392. https://doi.org/10.1016/j.iswcr.2022.01.002.
DOI: https://doi.org/10.1016/j.iswcr.2022.01.002

Interpretive Summary: Soil erosion removes fertile surface soil and, consequently, causes the loss of the associated essential nutrients from agricultural land. Eroded sediments may also deposit on the hillslope, hence affect the net loss of sediment and nutrients. In order to properly implement soil water and nutrient conservation practices, we need to know how different soil erosion regimes, i.e., soil erosion and sediment deposition, may affect carbon and nitrogen losses. We designed a laboratory rainfall study to quantify the influence of surface cover pattern on sediment and nutrient losses. Different surface cover patterns were implemented to simulate areas of active erosion from bare surface and deposition in covered areas. We measured dissolved organic nitrogen (DOC), dissolved inorganic nitrogen (DIN), dissolved organic carbon (DOC) and sediment-bound organic carbon (SBOC) during each rainfall event. The results showed that surface coverage level with different spatial distributions on slopes may cause a pronounced variability of erosion and deposition processes. An average of 81% of total nitrogen was in organic form and surface coverage significantly reduced the losses of sediment and sediment-bound organic carbon. Changes in the DON and DIN concentrations in successive rainfall events indicate different mechanisms controlled the release of soil nitrogen into runoff. These results suggested that covered surface areas could be managed to affect sediment transport and deposition, and consequently, soil carbon and nitrogen losses. Improving surface coverage needs to be incorporated in a sustainable management system for conserving soil, water, and nutrient resources.

Technical Abstract: Soil erosion not only removes fertile surface soil mass but also causes the loss of the associated essential nutrients from agricultural land. There is a need to quantify how soil erosion regimes may affect carbon and nitrogen losses in order to properly implement soil water and nutrient conservation practices. The aim of this study was to examine the influence of surface cover pattern on soil erosion and nutrient loss under a sequence of simulated rainfall events. Dissolved organic nitrogen (DOC), dissolved inorganic nitrogen (DIN), dissolved organic carbon (DOC) and sediment-bound organic carbon (SBOC) were measured in each rainfall event. The results showed that surface coverage level with different spatial distributions on slopes may alter erosion and covered zones and cause a pronounced variability of erosion and deposition processes. An average of 81% of total nitrogen was in organic form, suggesting that the DON contributed to a substantial amount of the soil nitrogen loss. DOC was responsible for the majority of organic carbon loss caused by the sediment, and SBOC was significantly reduced by surface coverage. Variations in the DON and DIN concentrations in successive rainfall events indicated different mechanisms controlled the release of soil nitrogen into runoff. Particle transport and deposition during an erosion event are important mechanisms affecting soil organic carbon loss. These results suggested that covered surface areas could be managed to affect erosion regimes (deposition-transport-dominated process), and consequently, affect the soil carbon and nitrogen losses. Therefore, improving surface coverage may be adopted as a sustainable management practice for soil, water and nutrient resources in agroecosystems.