Nitrogen accumulation in sole and mixed stands of sweet-blue lupin (Lupinus angustifolius L.), ryegrass and oats

• Published in: Plant and soil 1992-04, Vol.142 (1), p.135-142
• Main Authors: PÁLMASON, F., DANSO, S.K.A., HARDARSON, G.
• Format: Article
• Language: English
• Subjects: abonos nitrogenados; Agricultural soils; Agrology; avena sativa; Biological and medical sciences; Cereal grains; cultivo intercalado; cultivo puro; culture intercalaire; culture pure; engrais azote; fijacion del nitrogeno; fixation de l' azote; Fundamental and applied biological sciences. Psychology; intercropping; Intercrops; Legumes; lolium multiflorum; lupinus angustifolius; Mixed stands; Nitrogen; nitrogen fertilizers; Nitrogen fixation; Oats; Parasitism and symbiosis; Plant physiology and development; Plants; sole cropping; Symbiosis; technique des traceurs; tecnicas de trazadores; tracer techniques
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF00010183

Nitrogen fixation was measured in monocropped sweet-blue lupin (Lupinus angustifolius), lupin intercropped with two ryegrass (Lolium multiflorum) cultivars or with oats (Avena sativa) on an Andosol soil, using the ¹⁵N isotope dilution method. At 117 days after planting and at a mean temperature below 10°C, monocropped lupin derived an average of 92% or 195 kg N ha⁻¹ of its N from N₂ fixation. Intercropping lupin with cereals increased (p < 0.05) the percentage of N derived from atmospheric N₂ (% Ndfa) to a mean of 96%. Compared to the monocropped, total N fixed per hectare in intercropped lupin declined approximately 50%, in line with the decrease in seeding rate and dry matter yield. With these high values of N₂ fixation, selection of the reference crop was not a problem; all the cereals, intercropped or grown singly produced similar estimates of N₂ fixed in lupin. It was deduced from the ¹⁵N data that significant N transfer occurred from lupin to intercropped Italian ryegrass but not to intercropped Westerwoldian ryegrass or to oats. Doubling the ¹⁵N fertilizer rate from 30 to 60 kg N ha⁻¹ decreased % Ndfa to 86% (p < 0.05), but total N fixed was unaltered. These results indicate that lupin has a high potential for N₂ fixation at low temperatures, and can maintain higher rates of N₂ fixation in soils of high N than many other forage and pasture legumes.