|Abdul Baki, Aref|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/1998
Publication Date: N/A
Citation: N/A Interpretive Summary: Cover crops can provide many benefits to cropping systems including capturing residual soil nitrogen, preventing erosion, improving soil structure, fixing nitrogen for subsequent crop production, and suppressing weeds. No individual cover crop can provide all of these benefits when grown alone but mixtures of cover crops could increase the range of benefits derived from cover cropping. This research tested three important winter annual cover crops, hairy vetch, crimson clover, and rye, both alone and in mixtures for weed suppression and crop production in a fresh-market tomato system. Three years of research showed that cover crop mixtures produced more vegetative growth and similar amounts of nitrogen as individually grown cover crops. After mowing the cover crop before planting, the remaing mulch suppressed weed emergence and growth more in the cover crop mixtures than in the individual cover crops. Better weed suppression by the mixtures could be attributed to higher initial levels of mulch and to longer duration of the mulch. Cover crop mixtures did not reduce tomato yield compared to the standard hairy vetch cover crop treatment. Results suggest that additional benefits of fall nitrogen capture and summer weed suppression can be achieved without sacrificing crop yield by cover crop mixtures including rye with hairy vetch and/or crimson clover compared to a hairy vetch cover crop alone.
Technical Abstract: Monocrops and mixtures of hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and rye (Secale cereale L.) were compared for biomass production, nitrogen production, C:N ratio, and weed control for no-tillage production of staked, fresh-market tomatoes on raised beds in 1995 to 1997. There were few differences between the biomass of cover crop mixtures but biomass of cover crop mixtures were higher than the hairy vetch monocrop. The average biomass of hairy vetch, hairy vetch plus rye, crimson clover plus rye, and hairy vetch plus crimson clover plus rye was 5260, 7610, 8780, and 8420 kgùha-1, respectively. Cover crop nitrogen content varied little among legume monocrops and all mixtures but was lower in the rye monocrop. The range of C:N ratio was 13 to 15 for the hairy vetch monocrop, 18 to 27 for mixtures, and 51 to 56 for the rye monocrop suggesting that nitrogen immobilization was only a problem in the rye monocrop. Cover crop mixtures reduced weed emergence and biomass compared to the legume monocrops when no herbicide was applied; however, weed control was excellent in all cover crop treatments following a postemergence application of metribuzin. Marketable fruit yield was similar in the legume monocrops and all cover crop mixtures when followed by a metribuzin application but yield lower in the rye monocrop probably because of reduced nitrogen availability in that treatment. Yield was reduced in treatments without compared to those with herbicide despite weed suppression by cover crop mixtures.