| Distribution characteristics and stability of water\|stable soil aggregates in different alfalfa growth years in Loess Hilly\|Gully Region |
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| DOI：10.7606/j.issn.1000-7601.2020.05.08 |
| Key Words: alfalfa grassland growth years soil water\|stable aggregates particle size distribution stability soil physical and chemical properties Loess Hilly\|Gully Region |
| Author Name | Affiliation | | HAI Long | College of Resources and Environmental Sciences,Gansu Agricultural University, Lanzhou, Gansu 730070, China
Key Laboratory of Grassland Ecosystem, College of Pratacultural Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | YAO Tuo | Key Laboratory of Grassland Ecosystem, College of Pratacultural Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | ZHANG Chunhong | College of Resources and Environmental Sciences,Gansu Agricultural University, Lanzhou, Gansu 730070, China | | ZHANG Wenming | College of Resources and Environmental Sciences,Gansu Agricultural University, Lanzhou, Gansu 730070, China | | LI Linzhi | College of Resources and Environmental Sciences,Gansu Agricultural University, Lanzhou, Gansu 730070, China | | LU Yongli | College of Resources and Environmental Sciences,Gansu Agricultural University, Lanzhou, Gansu 730070, China |
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| Abstract: |
| In order to explore the effects of alfalfa planting on soil quality, a range of different lengths of growth years (3,7,12 a, and 18 a) and a tract of farmland nearby were selected in loess hilly\|gully region as objects for investigating soil aggregates size distribution in 0~60 cm soil layer. Soil samples were analyzed for fractionation of soil aggregates with wet\|sieving methods. The results showed that the proportion of water\|stable soil aggregates increased by 1.22%~61.43% with the decrease of particle size in studied area, and the dominant particle size was 60.83%~79.72% with micro aggregates (<0.25 mm). The topsoil (0~20 cm) in alfalfa grassland displayed a pronounced aggregation trend with the planting age to 12 a, which embodied the proportion of >2, 1~2, 0.5~1 mm, and 0.25~0.5 mm water\|stable aggregates of grassland soil was 2.03~2.75 times, 1.98~2.72 times, 1.31~1.65 times, and 1.15~1.36 times of farmland soil, respectively. Both mean weight diameter (MWD) and geometric mean diameter (GMD) in 0~20 cm soil were 12 a>18 a>7 a>3 a>CK, and the variation ranges were 0.34~0.70 and 0.18~0.26, respectively. Compared with farmland,alfalfa grassland fractal dimension (D) decreased significantly in 0~20 cm soil,ranging from 2.31 to 2.43. Correlation analysis showed that the proportion of >0.25 mm water\|stable aggregates (WSAP0.25), mean weight diameter (MWD), and geometric mean diameter (GMD) were positively correlated with soil total organic carbon (TOC). While there were no significant correlation between soil clay, CaCO3 content and indexes of soil aggregates. Our results confirmed that organic matter was the main cementing material for soil aggregation and alfalfa plantation could promote soil aggregation and increase the stability of soil aggregates in loess hilly\|gully region. |
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