Nitrogen transfer from forage legumes to grass in a systematic planting design. [Medicago sativa; Lotus corniculatus; Phalaris arundinacea]
Alfalfa (Medicago sativa L.) is the most important forage legume in the USA, but N transfer from this or other perennial forage species to companion grasses growing in a mixed sward is poorly understood. Furthermore, interplant distances and legume/grass ratios have seldom been controlled in studies of N transfer from legumes to non-legumes. The objectives of this field study were: (i) to determine the amount of N transferred from alfalfa and birdsfoot trefoil (Lotus carniculatus L.) to reed canarygrass (Phalaris arundinacea L.); (ii) to define conditions of distance and species ratio under which N transfer occurs; (iii) to compare the two legumes for N transfer; and (iv) to determine the effect of grass proximity on legume N/sub 2/ fixation. Legumes were interplanted with grass in single-species rows within km/sup 2/ plots on a Typic hapludoll soil labeled with /sup 15/N. Analysis of herbage showed significantly lower /sup 15/N concentration in grass near legumes than in grass grown alone, and significantly lower /sup 15/N concentration in legumes near grass than legumes in monoculture. Calculations using isotope dilution methods showed that grass derived a maximum of 68% of its N from alfalfa and 79% from trefoil. This N represented 13% of the N/sub 2/ fixed by trefoil and 17% of that fixed by alfalfa. The results indicated that N transfer occurred over a distance of 20 cm with maximum N transfer in areas of high legume/grass ratio. At third harvest, N derived from symbiosis was significantly higher (95% in alfalfa, 92% in trefoil) for legumes grown in mixture with grass than for legumes grown in monoculture (86% in alfalfa, 80% in trefoil). These results indicate that significant N transfer occurred, and that the amount of N transferred was dependent on interspecies distance and legume/grass ratio.
- Research Organization:
- Univ. of Minnesota, St. Paul
- OSTI ID:
- 6020292
- Journal Information:
- Crop Sci.; (United States), Vol. 27:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CROPS
SYMBIOSIS
GRASS
CULTIVATION TECHNIQUES
LEGUMINOSAE
ALFALFA
ISOTOPE DILUTION
LABELLED COMPOUNDS
NITROGEN 15
NITROGEN FIXATION
QUANTITY RATIO
BACTERIA
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
PLANTS
RHIZOBIUM
STABLE ISOTOPES
TRACER TECHNIQUES
553002* - Agriculture & Food Technology- Horticulture- (1987-)