HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Craig, L. d. A. Articles by McIntosh, M. S. Search for Related Content PubMed Articles by Craig, L. d. A. Articles by McIntosh, M. S. Agricola Articles by Craig, L. d. A. Articles by McIntosh, M. S.

Nitrogen Fixation Rates of Alfalfa and Red Clover Grown in Mixture with Grasses¹

Nitrogen contributions of legumes to grass-legume mixtures are estimated on the basis of legume monocultures and may need to be adjusted to reflect any effect of the companion grass. An experiment at two field locations was conducted to determine whether the N₂-fixation rates of alfalfa (Medicago sativa L.) and red clover (trifolium pratense L.) were significantly affected by mixed culture with orchardgrass (Dactylis glomerata L.) or timothy (Phleum pratense L.). Legumes and grasses were grown in eight mono- or mixed cultures. Specific nodule activity (SNA) was estimated by acetylene reduction at first flower of legumes and 4 weeks after initial harvest. Grasses were analyzed for total N (TN). Legume dry weight per plant was reduced by association with grasses in only one determination at one location. Grass TN 4 weeks after initial harvest was in most instances increased significantly by the legume. Specific nodule activities of red clover grown alone and red clover grown with grasses were similar and did not change between determinations. The SNA of alfalfa grown with grass was significantly higher than that of alfalfa grown alone for the second determination at one location. The SNA of alfalfa in mixed culture increased between determinations; however, SNA of alfalfa monocultures did not change. It is concluded that grass plants are not detrimental to legume plants and may stimulate N₂-fixation. Some transfer of N from legumes to grasses may occur when the two species are grown in mixed cultures.

Key Words: Medicago sativa L. • Trifolium pratense L. • Dactylis glomerata L. • Phleum pratense L. • Acetylene reduction • Total N • Specific module activity

² Former graduate research assistant and assistant professors of agronomy. Univ. of Maryland, College Park, MD 20742.

Received for publication December 15, 1980.