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Soil nutrients and carbon management indexes in the rhizosphere versus non-rhizosphere area of different plant species in desert grassland
- ZHANG Yi-Fan, CHEN Lin, LI Xue-Bin, LI Yue-Fei, YANG Xin-Guo
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2017, 26(8):
24-34.
DOI: 10.11686/cyxb2017077
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The main plant species used in the Ningxia Desert Grassland Vegetation Restoration Project are Caragana korshinskii, Artemisia ordosica, Stipa breviflora, and Agropyron mongolicum. The aim of this study was to explore the effects of different types of vegetation restoration on soil nutrients and carbon pool management index (CPMI) characteristics. We collected rhizosphere and non-rhizosphere soil from the surface (0-5 cm), subsurface (5-10 cm), and deep (10-15 cm) soil layers, and determined soil total carbon (Cr), active organic carbon (CA), carbon pool index (CPI) and CPMI. For all four plant species, soil nutrients decreased with increasing soil depth, and these decreases were greater in the rhizosphere soil than in the non-rhizosphere soil. The content of available potassium (AK) in the rhizosphere and non-rhizosphere of the C. korshinskii community was 130.81 and 111.96 mg/kg, respectively. The soil AK content showed a “fat island” aggregation effect on the desert steppe, and showed significant differences among the different communities (P<0.05). 2) The total organic carbon content in soil ranged from 2.09 to 17.11 g/kg, and was higher in the rhizosphere soil than in the non-rhizosphere soil. The vertical distributions of Cr and CA in the soil profile were similar, and showed a “poly table” effect. The carbon pool activity in the surface layer of the C. korshinskii and A. mongolicum community was 38.41% and 29.54% higher, respectively, than that in the deep layer. The four vegetation types could be ranked, from highest carbon pool activity to lowest, as follows: A. mongolicum>A. ordosica>C. korshinskii>S. breviflora. Vegetation restoration significantly improved the distribution of soil organic matter and the quality of the soil carbon pool, and increased the soil carbon sink function of the desert grassland. 3) The soil CPMI was significantly correlated with soil nutrient content in the desert grassland, and pH was negatively correlated with Cr, CA, CPI, and CPMI (correlation coefficients of -0.661, -0.437, -0.661, and -0.410, respectively). The soil CPMI was significantly or extremely significantly positively correlated with other soil nutrients (P<0.05; P<0.01). Higher soil N, P, and K contents promoted the soil carbon pool turnover rate, and significantly improved soil quality and productivity. These results show that CPMI serves as an effective index when evaluating soil quality and soil management practices.