Abstract
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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
