Jm. Moynihan et al., INTERCROPPING ANNUAL MEDIC WITH CONVENTIONAL HEIGHT AND SEMIDWARF BARLEY GROWN FOR GRAIN, Agronomy journal, 88(5), 1996, pp. 823-828
Interseeding annual legumes with grain crops has been proposed as a cr
opping strategy to enhance ground cover, thereby reducing weed competi
tion, suppressing soil erosion, and providing N for use by subsequent
crops. The potential of annual medics (Medicago spp.) for intercroppin
g in small-grain cropping systems has not been adequately assessed for
the north-central United States. Our objective was to evaluate a spri
ng barley (Hordeum vulgare L.)-annual medic intercrop system for barle
y grain yield, fall biomass production, suppression of fall weeds, and
quantity of N available for incorporation into the soil. Field experi
ments were conducted in four Minnesota environments (Becker, Morris, R
osemount, and St. Paul). Conventional height 'Robust' and semidwarf 'R
oyal' barley were intercropped with each of three medic species ['Geor
ge' black medic (M. lupulina L.), 'Mogul' barrel medic (M. truncatula
Gaertn.) and 'Santiago' burr medic (M. polymorpha L.)]. Intercropping
with medics reduced barley yields by an average of 6% at Rosemount, 30
% at St. Paul, and 76% at Becker, compared with monoculture barley fer
tilized with N. Medics increased yields by 9% at Morris. Intercropping
with medic reduced fall weed mass by an average of 65% across environ
ments, compared with the fertilized Royal monoculture. Nitrogen availa
ble for incorporation from the barley-medic intercrops ranged from 66
to 140 kg ha(-1) over the environments, whereas N available for incorp
oration from fertilized barley monoculture ranged from 22 to 80 kg ha(
-1) We conclude that the prospects for successfully intercropping with
annual medic in a barley grain production system are mixed and depend
in part on the medic species used and barley stature. A wider array o
f medic types should be evaluated for their suitability in intercroppi
ng with small grains.