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| Effects of Wheat and Rice Straw Returning on Soil Organic Matter Composition and Content of Different Nitrogen Forms in Soil |
| Received:May 31, 2015 |
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| KeyWord:straw returning;nitrogen forms;soil organic matter;element analysis;FTIR spectra |
| Author Name | Affiliation | E-mail | | ZHANG Ya-jie | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | CHEN Chen | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | CHEN Xi | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | CHANG Jiang | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | ZHANG Li-gan | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | GAO Hong-jian | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | gaohongjian2@163.com |
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| Abstract: |
| Effects of continuous wheat and rice straw returning on the content of different soil nitrogen forms and the composition of soil organic matter(SOM) were investigated in a 4-year field experiment. Five treatments included no straw returning and no fertilizer application(CK), straw returning without fertilizer application(S), straw returning with fertilization 1(SF1, C/N:12:1), straw returning with fertilization 2(SF2, C/N:18:1), and straw returning with fertilization 3(SF3, C/N:24:1). Compared with CK, content of SOM, soil total nitrogen and soil organic nitrogen increased by 7.8%, 10.6% and 10.9%, respectively, whereas soil inorganic nitrogen content decreased by 17.1% in treatment S. The content of soil total nitrogen, organic nitrogen and inorganic nitrogen in the SF2 treatment was 27.2%,27.2% and 25.7% higher than those in CK, respectively. Straw returning increased C% and N% of SOM and soil organic matter content, but decreased the ratios of C/N, H/C and O/C in SOM. FTIR analysis revealed that the signal intensities of 1650~1640 cm-1 and 3400 cm-1 of straw returning treatments were strengthened, demonstrating that the amounts of nitrogen compounds, alcohols, phenols and carboxylic acids in SOM increased. The strengthened signal intensity at 2920 cm-1 indicated an increase in the content of aliphatic compounds in SOM. Compared with CK, rice yields decreased by 8.8% in straw returning treatment with no fertilizer applied(S), but increased by 12.6%,22.7%,and 19.1% in SF1, SF2, and SF3 treatments,respectively. These findings indicate that wheat and rice straw returning increased the amounts of soil organic matter, soil total nitrogen and soil organic nitrogen, but decreased soil inorganic nitrogen and the ratios of C/N and C/H of SOM. Furthermore, straw returning elevated the content of soil organic nitrogen, such as amides and aromatic nitrogen in SOM, which are ready for crop utilization, while it lowered the amount of soil inorganic nitrogen including NH4+ and NO3-. |
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