Soil organic carbon dynamics under long-term fertilizations in arable land of northern China
- 1Ministry of Agriculture Key Laboratory of Crop Nutrition and Fertilization, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
- 2Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830000, China
- 3Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20740, USA
- 4Inst. of Soil and Fertilizer, Henan Academy of Agricultural Sciences, Zhengzhou, Henan 450002, China
- 5Inst. of Soil and Fertilizer & Agricultural sparing water, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China
- 6Inst. of Soil and Fertilizer, Jilin Academy of Agricultural Sciences, ChangChun, 130001, China
Abstract. Soil carbon sequestration is a complex process influenced by agricultural practices, climate and soil conditions. This paper reports a study of long-term fertilization impacts on soil organic carbon (SOC) dynamic from six long-term experiments. The experiment sites are located from warm-temperate zone with a double-cropping system of corn (Zea mays L.) – wheat (Triticum Aestivium L.) rotation, to mild-temperate zones with mono-cropping systems of continuous corn, or a three-year rotation of corn-wheat-wheat. Mineral fertilizer applications result in an increasing trend in SOC except in the arid and semi-arid areas with the mono-cropping systems. Additional manure application is important to maintain SOC level in the arid and semi-arid areas. Carbon conversion rate is significant lower in the warm-temperate zone with double cropping system (6.8%–7.7%) than that in the mild-temperate areas with mono-cropping systems (15.8%–31.0%). The conversion rate is significantly correlated with annual precipitation and active accumulative temperature, i.e., higher conversion rate under lower precipitation and/or temperature conditions. Moreover, soil high in clay content has higher conversion rate than soils low in clay content. Soil carbon sequestration rate ranges from 0.07 to 1.461 t ha−1 year−1 in the upland of northern China. There is significantly linear correlation between soil carbon sequestration and carbon input at most sites, indicating that these soils are not carbon-saturated thus have potential to migrate more CO2 from atmosphere.