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N2-fixing black locust intercropping improves ecosystem nutrition at the vulnerable semi-arid Loess Plateau region, China

Du, Baoguo, Pang, Junzhu, Hu, Bin, Allen, Diane E., Bell, Tina L., Pfautsch, Sebastian, Netzer, Florian, Dannenmann, Michael, Zhang, Shuoxin, Rennenberg, Heinz
The Science of the total environment 2019 v.688 pp. 333-345
Hippophae rhamnoides, Juglans regia, Robinia pseudoacacia, afforestation, ecosystems, forests, intercropping, labile carbon, landscape restoration, nitrogen, nitrogen fixation, nutrient availability, nutrition, phosphorus, plantations, semiarid zones, shrubs, soil, soil erosion, soil nutrients, trees, woody plants, China
The Loess Plateau in northwestern China constitutes one of the most vulnerable semi-arid regions in the world due to long-term decline in forest cover, soil nutrient depletion by agricultural use, and attendant soil erosion. Here, we characterize the significance of N2-fixing Robinia pseudoacacia L. and non-N2-fixing Juglans regia L. for improving nutrient availability and water retention in soil by comparing a range of biological and physicochemical features in monoculture and mixed plantations of both species. We found that N2-fixing Robinia facilitates the nitrogen and phosphorus composition of non-N2-fixing Juglans in the mixed stand as a consequence of improved soil nutrient availability, evident as higher levels of nitrogen and labile carbon compared to mono-specific stands. This demonstrates that intercropping N2-fixing Robinia with non-N2-fixing woody plants can greatly improve soil carbon and nitrogen bioavailability as well as whole-plant nutrition and can potentially mediate water retention with additional sequestration of soil organic carbon in the range of 1 t C ha−1 year−1. Thus, intercropping N2-fixing woody species (e.g. Robinia pseudoacacia or Hippophae rhamnoides L.) with locally important non-N2-fixing tree and shrub species should be considered in afforestation strategies for landscape restoration.