黄土区排土场复垦初期不同恢复模式下土壤生态化 学计量特征.

In order to explore the soil nutrient status and limitation of waste dump in loess area under different vegetation restoration modes at the initial stage of reclamation, 6 vegetation restoration models of Medicago sativa, Hippophae rhamnoides, Robinia pseudoacacia L., Robinia pseudoacacia, Bamboo willow and Populus bolleana with restoration years of 3-4 years were selected as the research objects, while the new waste was selected as the control. The soil organic carbon, nitrogen and phosphorus content and ecological stoichiometric characteristics and their relationships were studied. The results showed that the contents of soil organic carbon, total nitrogen and total phosphorus were 2.83-4.52 g·kg–1, 0.13-0.21 g·kg–1 and 0.05-0.17 g·kg–1 respectively. Except for soil total nitrogen of M. sativa and soil total phosphorus of M. sativa and R. pseudoacacia, the soil nutrient contents of other restoration models were higher than that in new waste dump. Soil organic carbon of R. pseudoacacia and M. sativa modes were higher while that of H. rhamnoides mode was lower, but soil, total nitrogen and soil total phosphorus were on the contrary. The content of soil total phosphorus was low under each restoration mode. Soil organic carbon and soil total nitrogen showed different degrees of surface accumulation under each restoration mode while the change of soil total phosphorus in vertical soil layer was not obvious. Soil C/N, C/P and N/P were 13.68-30.69, 19.30-106.60 and 1.13-3.61 under each restoration mode respectively. There were significant differences between the soil C/N, C/P and N/P of M. sativa and R. pseudoacacia restoration mode in vertical soil layers, which were higher than those in other modes. The correlation analysis showed that soil organic carbon and total nitrogen were closely related to soil nutrients and stoichiometric ratio. Soil C/N and C/P were more vulnerable to soil organic carbon, while soil N / P was more susceptible to soil phosphorus in the early stage of reclamation. In conclusion, the M. sativa and R. pseudoacacia restoration mode show lower mineralization rate of soil organic matter and are greatly limited by phosphorus, which needs to supply phosphorus fertilizer in time, but the recovery mode of P. bolleana needs to supply nitrogen fertilizer. [ABSTRACT FROM AUTHOR]