Monitoring of soil organic carbon and nitrogen stocks in different land use under surface water erosion in a semi-arid drainage basin of Iran

F Ahmadi,K Nosrati

doi:10.4314/jasem.v17i2.6

Abstract

Soil organic carbon (SOC) and soil nitrogen (SN) are the principal components in soil quality assessment, and in mitigation the global greenhouse effect. In Iran, little information exists on the stocks of SOC and SN. SOC and SN stocks are a function of the SOC and SN concentrations and the bulk density of the soil that are prone to changes under land use types and soil erosion. The objective of this study was to evaluate SOC and SN stock in different land use types under surface erosion at catchment scale. In view of this, bulk density, SOC and SN concentration were measured in 39 different sampling sites of three main groups of land use affected by surface erosion namely, rangeland, crop field, and forest land at Taleghani catchment, Khoramabad, Iran. The results showed that SOC and SN stock under all land use types was significantly different (P rangeland (63.3 Mg ha −1 ) > crop field (47.2 Mg ha −1 ; P < 0.01). Also the SN stock had the same trend in all studied land uses. These results can be useful as a scientific basis for selecting the proper soil management as a simple and low-cost approach to mitigate the SOC and SN loss. ©JASEM Keywords : SOC stock; SN stock; Land use; Surface waterr erosion; Taleghani catchment

Highlights

Soil erosion is a global environmental problem, which refers to the displacement of soil from the place of its formation by causative agents, including raindrops, runoff, wind and gravity (Lal, 2003)
soil organic carbon (SOC) stock was highest for forest land use sites for 0– 30 cm soil layers (P < 0.01; Fig. 2), which showed the important contribution of soil organic towards enhancing SOC stock
The mean SOC stock for 0–30 cm soil layer under different land uses varied in order forest (66.9 Mg ha−1) > rangeland (63.3 Mg ha−1) > crop field (47.2 Mg ha−1; P < 0.01) (Table 2 & Fig. 2)

Summary

Introduction

Soil erosion is a global environmental problem, which refers to the displacement of soil from the place of its formation by causative agents, including raindrops, runoff, wind and gravity (Lal, 2003). Water erosion as the principal component of total soil erosion is the removal of a thin layer of particulate matter across the land surface and truncating the A horizon, which can redistribute considerable amounts of soil, soil organic carbon (SOC) and soil nitrogen (SN). Soil erosion alters the fluxes of SOC and SN because removes and redistributes the C- and Nenriched sediment and accelerates the process of mineralization (e.g., C emissions). Increase of SOC and SN loss by land use changes and soil erosion decrease SOM/SOC and reduce the satisfactory level of SOC and TN that is necessary for sustainable agroecosystems. Knowledge of soil organic carbon and nitrogen stocks are important to reduce CO2 emission to the atmosphere. Accelerated soil erosion is a serious problem in Iran, leading to soil degradation and decreasing SOC and SN stocks.

Objectives

Methods

Results

Conclusion