Abstract
Carbon sequestration in cropland soils which could be achieved through improved management practices (IPMs) represents an important opportunity to offset a portion of greenhouse gas emissions. North China is the main wheat and maize production region where many IMPs have been widely used during the last several decades, but the effect size and duration of IMPs on soil organic carbon (SOC) sequestration in wheat-maize double cropping system in this region is scarcely studied. In this study, a meta-analysis was conducted to compare the effect size and duration of four IMPs on SOC sequestration in wheat-maize double cropping system in north China. A total of 29 long-term experiments, consisting of 119 paired treatments were compiled in this analysis. The results indicated that the four IMPs of organic manure application (OM), organic manure combined with chemical fertilizer application (MF), straw return (SR) and reduced or no tillage (RNT) all had significant effects on SOC sequestration in the study area. On average, the IMPs of OM, MF, SR and RNT enhanced SOC density by 260, 328, 278 and 134 kg ha-1 yr-1, respectively. The effect duration of OM, MF, SR and RNT on SOC sequestration were about 48, 26, 22 and 18 years, respectively. Accumulation enhancements of SOC for OM, MF, SR and RNT over SOC sequestration period were about 34.7%, 36.1%, 22.0% and 12.7%, respectively. OM and MF could be the appropriate practices on SOC sequestration in wheat-maize double cropping system in the research area.
Highlights
The concentration of CO2 in the atmosphere has increased from 280 μmol mol-1 before industry revolution to 379 μmol mol-1 in 2005, and it would be increasing by 1.9 μmol mol-1 per year (IPCC, 2007)
The results indicated that the four improved management practices (IMPs) of organic manure application (OM), organic manure combined with chemical fertilizer application (MF), straw return (SR) and reduced or no tillage (RNT) all had significant effects on soil organic carbon (SOC) sequestration in the study area
OM can sequester SOC an average of 260 kg ha-1 yr-1, which was higher than that of 150 kg ha-1 yr-1 in Europe cropland concluded by Vleeshouwers and Verhagen (Vleeshouwers & Verhagen, 2002), lower than that of previous researchers with an effect of 390 kg ha-1 yr-1 of USA cropland estimated by Jarecki et al (Jarecki, Lai, & James, 2005), 350 kg ha-1 yr-1 of Belgium cropland evaluated by Dendoncker et al and 510 kg ha-1 yr-1 in southeastern USA estimated by Upendra et al ( Upendra et al, 2008; Dendoncker, Wesemael, & Rounsevell, 2004)
Summary
The concentration of CO2 in the atmosphere has increased from 280 μmol mol-1 before industry revolution to 379 μmol mol-1 in 2005, and it would be increasing by 1.9 μmol mol-1 per year (IPCC, 2007). Many researchers have studied the effects of the IMPs on C sequestration in cropland soils through long-term experiments (Morari, et al, 2006; John, Marcus, Ronald, & James, 2008; Upendra, Zachary, Ermson, Irenus, & Reddy, 2008; Wang & Kang, 2009), the results among them were always inconsistent and uncertain varying from significant increase to significant decrease (Alvaro-Fuentes, Lopez, Cantero-Martinez, & Arrue, 2008; Christopher, Lal & Mishra, 2009) It was unclear whether this inconsistency was caused by environmental, or management factors or by sampling errors and analysis methodology (Luo, Wang, & Sun, 2010). The results of each research only represented a particular plot site, which could not represent a region
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