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| Distribution characteristics of soil aggregates and their associated organic carbon under different irrigation modes with reclaimed water |
| Received:August 31, 2019 |
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| KeyWord:reclaimed water;irrigation mode;soil aggregate;soil organic carbon |
| Author Name | Affiliation | E-mail | | HU Ting-fei | College of Water Resources and Civil Engineering, Hunan Agricultural University, Changsha 410128, China | | | WANG Hui | College of Water Resources and Civil Engineering, Hunan Agricultural University, Changsha 410128, China | wanghuisb@126.com | | TAN Shuai | College of Water Resources and Civil Engineering, Hunan Agricultural University, Changsha 410128, China | |
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| Abstract: |
| The effects of reclaimed water irrigation modes on the content and stability of soil aggregates, total soil organic carbon, and distribution of aggregate-associated organic carbon in three subtropical soils, i.e., tidal soil, purple soil and paddy soil, were investigated. An indoor simulation experiment was conducted at the irrigation and drainage laboratory of the college of water resources and civil engineering of Hunan agricultural university. Four treatments were designed as follows:fresh water irrigation(CK), reclaimed water irrigation(RW), alternative irrigation of fresh water and reclaimed water(ARW), and mixed irrigation of fresh water and reclaimed water(RW-2). Soil samples were collected from 0~15 cm soil layers in the plots of the four treatments for analysis. Using the dry sieving and wet sieving method, the proportions of aggregates >5 mm, 2~5 mm, 0.5~2 mm, 0.25~0.5 mm, and <0.25 mm in size were obtained, and then the mean weight diameter(MWD) and geometric mean diameter(GMD) of the fractions of soil aggregates were calculated. The organic carbon contents of the soil and aggregates were also discussed. The results showed that regardless of treatment, the aggregates of three subtropical soils were dominated by macroaggregates(>0.25 mm). The proportion of macroaggregates were 89.56%~97.91% and 67.95%~81.81% by dry sieve and wet sieve, respectively. Compared with CK, the MWD and GMD of tidal soil and paddy soil aggregates decreased in the three irrigation treatments, while that of purple soil increased; the differences between tidal soil and purple soil were significant(P<0.05). The total organic carbon and macroaggregate-associated organic carbon contents in tidal soil and purple soil increased significantly(P<0.05), while that of paddy soil did not change significantly. The organic carbon content of macroaggregates was 8.83~29.95 times higher than that of microaggregates. The former contributed 89.42%~97.09% of the total soil organic carbon content while the latter contributed 2.91%~10.58%. We conclude that purple soil and paddy soil are more suitable for RW. RW improves purple soil agglomeration and organic carbon retention, while paddy soil is more suitable for RW-2. |
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