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| Title: | Carbon budget of a winter-wheat and summer-maize rotation cropland in the North China Plain |
| Author: | Yuying Wang, Chunsheng Hu, Wenxu Dong, Xiaoxin Li, Yuming Zhang, Shuping Qin, Oene Oenema |
| PubYear: | 2015 |
| Publication Name: | Agriculture, Ecosystems & Environment |
| Volume、Issue、Page Number: | 206; ; 33-35 |
| Impact Factor: | |
| Abstract: | Crop management exerts a strong influence on the agroecosystem carbon (C) budget. From October 2007 to October 2008, the net C budget of an intensive winter-wheat and summer-maize double cropping system in the North China Plain (NCP) was investigated in a long-term field experiment with crop residues input, using a combination of eddy covariance, crop growth and soil respiration measurements. The objectives were to qualify the annual C budget and to establish the effects of climatic variables and crop management on C budget. The net ecosystem exchange of CO2 (NEE) was partitioned into gross primary production (GPP) and total ecosystem respiration (TER); meanwhile, net primary production (NPP) and soil respiration (SR) were determined to compute autotrophic and heterotrophic respirations. Results showed that the NEE, NPP and SR were 359, 604 and 281 g C m？2 in wheat season respectively, and 143, 540 and 413 g C m？2 in maize season respectively. Autotrophic respiration dominated TER and was mainly driven by GPP. The net C budget was calculated seasonally based on NPP and considering C input through crop residues and C output through grain harvest. We found the winter-wheat system was a C sink of 90 g C m？2; whereas, the summer-maize system was a C source of 167 g C m？2. Thus, the double cropping system behaved as a C source of 77 g C m？2 on an annual basis, corresponding to an annual average loss rate of nearly 1% in topsoil organic carbon stocks during 2003–2008. Though the season length was 52% shorter for maize (113 days) than that for wheat (235 days), over 55% of the CO2 emissions originated from the warmer and rainy maize season; this implies that the inter seasonal climate variability affected the C flux dynamics mainly and the interaction of soil temperature and moisture is the “single” dominant factor for ecosystem respiration in this area. Our study provides evidence that C was being lost from the intensive wheat-maize double cropping system in the NCP at a rate of 77 g C m？2 year？1 when harvest removals were considered, even though crop residue C was inputted into the soil since 30 years ago. |
| DOI: | http://dx.doi.org/10.1016/j.agee.2015.03.016 |
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