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| Effects of Long-term Fertilization on Soil Physical Properties and Aggregate Organic Carbon Accumulation in Paddy Soils of Dongting Lake Region, China |
| Received:November 27, 2014 |
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| KeyWord:fertilization;paddy soil;physical properties;soil aggregates;organic carbon;Dongting Lake region |
| Author Name | Affiliation | | LI Wen-jun | Hunan University of Arts and Science, Changde, 415000, China
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | PENG Bao-fa | Hunan University of Arts and Science, Changde, 415000, China | | ZHOU Shi-biao | Hunan University of Arts and Science, Changde, 415000, China | | WANG Ya-li | Hunan University of Arts and Science, Changde, 415000, China | | CHEN Duan-lü | Hunan University of Arts and Science, Changde, 415000, China | | TONG De-bao | Agricultural Bureau of Hanshou County, Hanshou 415900, China | | LI Hong-zhuan | Agricultural Bureau of Hanshou County, Hanshou 415900, China |
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| Abstract: |
| Soil physical properties and organic carbon are important indexes of soil quality, which are sensitive to fertilization practices. Based on a 27-year fertilization experiment on paddy field in Dongting Lake region, China, the responses of soil physical properties and dry sieved aggregate-associated organic carbon to applications of nitrogen(N), phosphorus(P) and potassium(K) mineral fertilizers with or without organic manure were studied at 0~20 cm and 20~40 cm soil layers. Compared to long-term unfertilized treatments, the soil total porosity and field moisture capacity in the two soil layers under fertilizer application increased by 2.6%~8.3% and -3.0%~23.5%, respectively, while the soil bulk density decreased by 3.0%~11.6%,which were significant(P<0.05) at 0~20 cm layer but not at 20~40 cm layer. The amount of soil aggregates in the >5 mm group decreased after long-term fertilization, while the proportions of aggregates in 2~5 mm and 0.5~2 mm groups increased significantly(P<0.05) by 57.3%~94.3% and 25.8%~103.8%, respectively, in two soil layers. These meant that the physical structure of paddy soil was improved by long-term fertilization. Along with aggregates size decreasing, the contents of aggregates-associated organic carbon increased, but storages presented an opposite trend. Both mineral and organic fertilizers applications significantly(P<0.05) increased the organic carbon contents in various size classes of aggregates, but such effects decreased with increasing soil depths. Organic carbon storages in the <5 mm aggregates in two soil layers were significantly higher in all fertilization treatments(P<0.05)than those of no fertilizer treatment, but the storages of aggregates-associated organic carbon in the 2~5 mm and 0.5~2 mm aggregates were more sensitive to long-term fertilization than in others. It can be concluded that the improvements of soil quality varied with different fertilization modes. Combined application of N, P, K fertilizers and organic manure was better than balanced application of N, P, K fertilizers in improving soil physical properties and enhancing carbon sequestration in aggregates. With increasing rates of manure applications, the improvement of soil quality would become more distinct. |
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