Abstract
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.
Highlights
Soil organic carbon (SOC) is an important index of soil fertility because of its relationship to crop productivity (Vinther et al, 2004; Pan et al, 2009)
Because of the potential of agro-ecosystems to absorb a large amount of atmospheric carbon dioxide through soil carbon sequestration, SOC management is recognized as a “win-win strategy” (Smith et al, 1999; Lal, 2002), and has been put forward as one of the mitigating options for global climate change (Post et al, 2004)
The NPK combinations with livestock or farmyard manure (NPKM) and/or higher application rate of NPKM (hNPKM) treatments lead to the highest carbon biomass
Summary
Soil organic carbon (SOC) is an important index of soil fertility because of its relationship to crop productivity (Vinther et al, 2004; Pan et al, 2009). Maintaining SOC level is essential for agricultural sustainability. The concept of sustainable agricultural production emphasizes the importance of SOC management for food security and environment protection (Buyanovsky and Wagner, 1998; Pan et al, 2009). Because of the potential of agro-ecosystems to absorb a large amount of atmospheric carbon dioxide through soil carbon sequestration, SOC management is recognized as a “win-win strategy” (Smith et al, 1999; Lal, 2002), and has been put forward as one of the mitigating options for global climate change (Post et al, 2004). It is estimated that, in China, the potential of soil carbon sequestration may offset more than 10% of the annual fossil fuel emissions (Lal, 2004)
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