Grazing system and stocking rate effects on forage standing crop of ta
llgrass prairies in north-central Oklahoma were evaluated from 1989 to
1993. Twelve experimental units, consisting of pastures dominated by
big bluestem [Andropogon gerardii Vitman], little bluestem [Schizachyr
ium scoparium (Michx.) Nash], indiangrass [Sorghastrum nutans (L.) Nas
h], and switchgrass [Panicum virgatum L.], were arranged in a complete
ly randomized design with either a short duration rotation or continuo
us grazing system and stocking rates ranging from 127 kg animal live-w
eight/ha to 222 kg live-weight/ha. Yearling steers grazed the units fr
om late April to late September. Herbage standing crop was sampled in
July and September. Total, live, and dead standing crops did not diffe
r significantly between the 2 grazing systems in July. Total standing
crop was significantly higher in the rotation units in September (3,60
0 versus 3,020 kg/ha, P<0.05). Dead standing crop was also higher in t
he rotation units in September (1,950 versus 1,570 kg/ha, P<0.05). Evi
dence suggests the difference in standing crop between systems is due,
in part, to reduced forage intake by the livestock. Grazing system di
d not interact with either stocking rate or year. Stocking rate had si
gnificant effects on total, live and dead standing crops at both sampl
e dates. The slope of the total standing crop-stocking rate relationsh
ip varied over years and ranged from -12 to -36 kg/ha per kg live-weig
ht/ha in July and from -12 to -27 kg/ha per kg live-weight/ha in Septe
mber. Higher standing crop at the end of the grazing season in the rot
ation units would mean greater soil protection and higher fuel loading
for prescribed burning, and would suggest a lower impact on plant vig
or. However, if the higher standing crop is a result of lower forage i
ntake, we would expect livestock weight gains to decline.