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Research article2021Peer reviewedOpen access

Species Interactions and Nitrogen Use during Early Intercropping of Intermediate Wheatgrass with a White Clover Service Crop

Li, Shoujiao; Jensen, Erik Steen; Liu, Nan; Zhang, Yingjun; Dimitrova Martensson, Linda-Maria


Perennial grain crops intercropped with legumes are expected to use nitrogen (N) resources efficiently. A pot experiment using the N-15 isotope dilution method demonstrated interspecific competition and use of N from the soil and N-2 fixation in intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey, IWG) and white clover (Trifolium repens L., WC) intercrops at five species-relative frequencies and four levels of inorganic N fertilizer in a replacement series design. The proportion of N in WC derived from the atmosphere increased from 39.7% in a sole crop to 70.9% when intercropped with IWG, and 10.1% N in IWG transferred from WC. Intermediate wheatgrass showed high fitness with maintained high total dry matter production at low relative frequencies. Decreasing IWG-relative frequency only increased dry matter and N accumulation of WC, resulting in increased amounts of N-2 fixed. Increased levels of N fertilization increased the proportion of N acquired from the fertilizer in IWG and WC but decreased the N fixed by WC and N absorbed by IWG from the soil. Our study indicates that WC supply sufficient fixed N-2 for IWG intercrop biomass yields under appropriate levels of soil N fertility and species-relative frequencies.


symbiotic N-2 fixation; apparent transfer of N; intercropping advantages; interspecific interactions; intermediate wheatgrass; white clover; service crop

Published in

2021, Volume: 11, number: 2, article number: 388
Publisher: MDPI

      SLU Authors

      • Associated SLU-program

        Future Agriculture (until Jan 2017)

        Sustainable Development Goals

        Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
        End hunger, achieve food security and improved nutrition and promote sustainable agriculture
        Ensure sustainable consumption and production patterns

        UKÄ Subject classification

        Agricultural Science

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