Quantifying biological nitrogen fixation of different catch crops, and residual effects of roots and tops on nitrogen uptake in barley using in-situ 15N labelling

• Published in: Plant and soil 2015-10, Vol.395 (1-2), p.273-287
• Main Authors: Li, Xiaoxi, Sørensen, Peter, Li, Fucui, Petersen, Søren O, Olesen, Jørgen E
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; catch crops; crop yield; Ecology; forage; Life Sciences; Lolium perenne; nitrogen; nitrogen content; nitrogen fertilizers; nitrogen fixation; Plant Physiology; Plant Sciences; radishes; Regular Article; residual effects; roots; soil; Soil Science & Conservation; spring; spring barley; stable isotopes; Trifolium pratense; Vicia villosa subsp. villosa
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-015-2548-8

BACKGROUND AND AIMS: Contributions of legume-based catch crops (LBCCs) to succeeding cereals may be significant. We quantified biological N fixation (BNF) and residual N effects of contrasting CC tops and roots. METHODS: BNF of three LBCCs (red clover, winter vetch, perennial ryegrass-red clover mixture) was quantified in microplots by ¹⁵N labelling. Their residual effects on spring barley were tested against two non-LBCCs (perennial ryegrass, fodder radish) after spring incorporation of CC tops or roots in monoliths. RESULTS: Total N accumulated in LBCCs was 153–226 kg N ha⁻¹, of which 62–66 % was derived from BNF in tops and 31–46 % in macro-roots (0–18 cm soil). Macro-roots represented 31–50 % of total plant N. LBCCs showed similar capacity for soil N extraction as non-LBCCs. After incorporation of LBCC residues, the dry matter and N yields of spring barley were comparable to the effect of 50 kg N fertilisation ha⁻¹, whereas no extra N uptake was derived from non-LBCCs. The ¹⁵N-based N fertiliser values of LBCC tops were 34–47 % against 26–29 % for non-LBCCs. CONCLUSIONS: LBCC roots contributed substantial amounts of N to the system, a source that is usually underestimated. N immobilisation after incorporation of non-LBCCs may hamper the growth of following main crops especially after removing tops.