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| DOI：10.13522/j.cnki.ggps.20180438 |
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| Effect of Different Fertilizations Patterns on Soil Carbon and Nitrogen Changes of Dryland Wheat Field in Southern Shanxi of China |
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LI Tingliang, LI Shun, XIE Yinghe, GAO Zhiqiang, WANG Ruixin, MA Hongmei, LI Li
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1.College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China; 2. National Demonstration Center for Agricultural Resources and Environment Experimental Teaching, Shanxi Agricultural University, Taigu 030801, China; 3.Collage of Agriculture，Shanxi Agriculture University, Taigu 030801, China
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| Abstract: |
| 【Objective】 The objective of the study is to determine the changes of soil carbon and nitrogen under different fertilizations, and to provide the theoretical support for reducing chemical fertilizer application rate and improving soil fertility in the rainfed winter wheat system.【Method】 The study was carried out with three fertilization treatments, including the farmer fertilization (FF), the monitoring fertilization (MF) and no fertilization (NF), during 2012─2017 in the winter wheat cropping region of dry highland in Southern Shanxi. The changes of soil total organic carbon (TOC) and nitrogen (TON), organic carbon and nitrogen fractions, and soil nitrate-N residue in the 0~200 cm soil profile were assessed. 【Result】 Soil TOC concentration under NF treatment in 2017 increased by 24.7% compared to that in 2012, which under FF and MF treatments decreased by 2.4%~8.2%. Continuous chemical fertilizer application was more beneficial to the increase of soluble organic carbon (SOC), soluble organic nitrogen (SON), and light fraction organic carbon (LFOC) compared to NF treatment, in addition, the effect of MF treatment on the increase of SOC was larger than that of FF treatment. The proportion of LFOC in the TOC under different treatments ranged from 17.9% to 31.3%, therefore, heavy fraction organic carbon (HFOC) was considered to be the main form of soil organic carbon sequestration in the wheat field. Compared to the FF and MF treatments, the NF treatment significantly increased the HFOC concentration, which was favorable?for soil organic carbon sequestration. However, no significant difference in both light fraction organic nitrogen (LFON) and heavy fraction organic nitrogen (HFON) were observed among different fertilization treatments. The accumulation amounts of nitrate nitrogen in 0~200 cm soil layer under the FF treatment had been up to 426.0 kg/hm2, 67% of nitrate nitrogen concentrated on the 100~200 cm soil profile with a strong leaching risk. In contrast, soil nitrate-N residue in 0~200 cm soil profile under the MF treatment reduced by 51.4% compared to that under the FF treatment, meanwhile, the rate of nitrogen application under the of FF treatment also decreased by 36.9%. 【Conclusion】 Based on excessive nitrogen application before the experiment began, no fertilization along with straw returning increased the HFOC concentration in rainfed winter wheat cropping region on the Loess Plateau. Single chemical fertilizer applications could facilitate the decomposition of soil organic matter, resulting in an increasing of labile organic carbon and nitrogen fractions. A large amount of?nitrate-N residue was observed in the 0~200 cm soil profile under traditional farmer fertilization with a potential leaching risk. |
| Key words: dry highlands in Southern Shanxi; fertilizations patterns; organic carbon; organic nitrogen; nitrate-N residue; soil |
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