Title: Using 137Cs and 210Pbex to quantify the effects of land use on soil organic carbon and total nitrogen in the subtropical Dianchi watershed, southwest China

Authors: Mingli Zhang; Xia Wang; Biao Xie; Yong Zhang

Addresses: School of Geography Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China ' Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, 8 Jiangwangmiao Street, Nanjing 210042, China ' School of Environment, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China ' School of Environment, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China

Abstract: The conversion from forest to agricultural land in the last three decades represents a significant shift in land use in China. However, few direct measurements have been made to investigate the dynamic processes of soil organic carbon (SOC) and total nitrogen (TN) under land use change. Our results showed that converting forest to grassland and farmland led to the increase in SOC content, decrease of TN concentration and C:N ratio in the top soil. The erosion rate and nutrient loss estimated by 137Cs showed highest under farmland. The highest nutrient losses were found in cultivated farmland, with 4.08 and 0.40 t km−2 year−1 for SOC and TN respectively. We conclude that forest system could be an effective strategy to improve SOC stocks in the subtropical Dianchi watershed. The accumulation of N in cultivated farmland soils poses a potential threat to nearby Dianchi Lake.

Keywords: soil organic carbon; SOC; total nitrogen; 137Cs and 210Pbex; Dianchi watershed; C:N ratio; China.

DOI: 10.1504/IJEP.2018.093012

International Journal of Environment and Pollution, 2018 Vol.63 No.1/2, pp.69 - 88

Accepted: 20 Sep 2017
Published online: 26 Jun 2018 *

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