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Climatic Adaptation and Reseeding Potential of
Alternative Annual Legumes in Southwest Arkansas
K. A. Cassida and C. B. Stewart 1
Story in Brief
Climatic adaptation and reseeding ability of subterranean, persian, rose and balansa clovers, and burr, button, and
black medics were evaluated at the Southwestern Research and Extension Center in Hope, Arkansas. Legumes were
drilled into clean seedbeds on a Sacul fine sandy loam soil during October 1999, harvested once in spring 2000 when
they reached full bloom, and then allowed to regrow and reseed themselves. Reseeded stands were harvested in April
2001. Subterranean clovers were low-yielding but the best reseeders. Rose clover, balansa clover, and button medic had
the highest yields in the planted year. Subclovers, balansa clover, persian clover, burr medics and button medics produced
good seedling stands in the reseeding year. Persian clover suffered some winter kill in the reseeding year, and
yields of medics were reduced by weevil infestation. Balansa, persian, rose, and subterranean clovers and burr and button
medics have sufficient climatic adaptation and reseeding ability to warrant further testing for pasture or hay production
in southern Arkansas.
Introduction
Legumes are nearly universally desired in mixed
species forage stands, where a primary benefit is nitrogen fixation.
However, they are difficult to maintain in pastures and
hayfields in southern Arkansas. Humidity, high night temperatures
during summer, and disease and insect pressures combine
to cause very poor persistence of perennial legume
species such as alfalfa, white clover, and red clover that are
the mainstays in more temperate parts of the US. Producers
who use legumes in southern Arkansas rely heavily on annual
legumes such as crimson and arrowleaf clovers. However,
planting these legumes every year represents an additional
cost of production that might be avoided if a legume that will
reliably reseed itself could be identified.
The key factors for assessing suitability of annual
legumes in a complete forage system are: 1) enough cold tolerance
to survive southern Arkansas winters, 2) tolerance of
waterlogged soil conditions in winter, and 3) ability to regrow
and set seed after moderate defoliation such as might occur
with managed grazing or a spring hay cutting. Therefore, a
screening trial was conducted to evaluate local climate adaptation
and reseeding potential of clovers and medics that have
not been widely used in Arkansas.
Experimental Procedures
Plots were established on a clean-tilled Sacul fine
sandy loam soil at the Southwestern Research and Extension
Center in Hope, Arkansas. Soil pH was 6.7, and the site was
fertilized with 30 lb/acre of N, P, and K prior to planting in
1999 and again in October 2000. Legumes were inoculated
with the appropriate rhizobia and drilled on October 27,
1999. Legumes were selected for the trial based upon success
in environments similar to southwestern Arkansas. Legume
species, cultivars, and planting rates used were: subterranean
clover (Trifolium subterraneum L., >Denmark=,
>Goulburn=, 20 lb PLS/acre), balansa clover (T. balansae
Boiss., >Paradana=, 10 lb/acre), persian clover (T. resupinatum
L., >Nitro=, 5 lb/acre), rose clover (T. hirtum All.,
>Overton R18', 20 lb/acre), burr medic (Medicago polymorpha
L., >Armadillo=, >BECOM=, 15 lb/acre), button medic
(M. orbicularis All., wild collection,15 lb/acre), and black
medic (M. lupulina L., >George=, >BEBLK=, 15 lb/acre).
Button medic was scarified prior to planting. Plots were
sprayed with Poast Plus (sethoxydim, 1.5 pint/acre) in
February 2000 and 2001 to control annual ryegrass.
Plots were visually scored for percent ground cover at
intervals after planting, after harvest, and after emergence of
seedlings in the reseeding year. Weed presence, winter kill,
diseases, and insect damage were monitored. Plots were harvested
using a sickle bar harvester at a stubble height of 3
inches. Plots were harvested as close as possible to full bloom
stage. In 2000, balansa clover, persian clover, both burr
medics, and BEBLK black medic were clipped on March 20
and the remaining legumes were clipped on May 25.
Subsamples were hand-sorted into legume and broadleaf
weeds, and legume yield determined. Plots were then allowed
to regrow and set seed. Seedling emergence date was noted
and development was monitored as visual estimates of percent
ground cover of live clover plants through the following
growing season. In 2001 all reseeded legume plots except
rose clover were harvested on April 18; rose clover was har-
1 Southwest Research and Extension Center, Hope.
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