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Inoculation and Nitrogen Affect Herbage and Symbiotic Properties of Annual Medicago Species
Author(s) -
Zhu Yanping,
Sheaffer Craig C.,
Vance Carroll P.,
Graham Peter H.,
Russelle Michael P.,
Montealegre C. M.
Publication year - 1998
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1998.00021962009000060011x
Subject(s) - biology , inoculation , agronomy , dry matter , sinorhizobium meliloti , medicago sativa , loam , sinorhizobium , sowing , medicago , nitrogen fixation , microbial inoculant , rhizobia , horticulture , soil water , bacteria , gene , ecology , genetics , biochemistry
The interactive effects of Sinorhizobium inoculants and soil N status should affect the N contribution of annual medics ( Medicago spp.) in cropping systems. We determined the effect of N and commercial medic inoculum on nodulation, dry matter, and N yield of annual medics and also determined Sinorhizobium strain occupancy in annual medic nodules. Field experiments were conducted on a sandy, mixed Udorthentic Haploboroll and on a fine‐loamy, mixed, mesic Typic Hapludalf. More than 75% of annual medic plants (except M. rugosa Desr.) were nodulated in the absence of commercial inoculum, and nodulation was due in part to a Sinorhizobium strain that frequently nodulates alfalfa ( Medicago sativa L.). Among the five strains in the commercial medic inoculum, 102G3 and 102A13 had the greatest nodule occupancy. When no N was applied, inoculation improved the percentage of plants nodulated and nodule mass only in M. rugosa, compared with no inoculation, but inoculation increased herbage yields of spring‐seeded M. truncatula Gaertn. cv. Sephi, M. polymorpha L., and M. rugosa by about 60%, compared with no inoculation. Nitrogen addition reduced the nodule mass of all species when inoculum was applied, and N addition increased only the herbage dry matter yield of spring‐seeded M. scutellata (L.) Mill. when inoculum was applied. This suggests that a more effective inoculum could be developed for M. scutellata so that N would not limit herbage growth. Annual medics fixed from 40 to 80 kg N ha −1 if spring‐seeded and grown for 60. d, and from 20 to 50 kg N ha −1 if summer‐seeded and grown for 43 d.