Rm. East et P. Felker, FORAGE PRODUCTION AND QUALITY OF 4 PERENNIAL GRASSES GROWN UNDER AND OUTSIDE CANOPIES OF MATURE PROSOPIS-GLANDULOSA TORR VAR GLANDULOSA (MESQUITE), Agroforestry systems, 22(2), 1993, pp. 91-110
Comparisons were made of dry matter production and forage quality of t
wo cool-season grasses, Canada wildrye (Elymus canadensis L.), Virgini
a wildrye (Elymus virginicus L.), and two warm-season grasses, green p
anic (Panicum maximum var. trichoglume Eyles) and plains bristlegrass
(Setaria leucopila Scribn. & Merr.), planted under and outside the can
opies of mature honey mesquite (Prosopis glandulosa Torr. var. glandul
osa). Green panic gave the greatest cumulative dry matter yield in bot
h canopy (5120 kg ha-1) and open (3370 kg ha-1) locations, followed by
plains bristlegrass under mesquite (1130 kg ha-1) and in the open (57
0 kg ha-1). One-time yields from Canada wildrye and Virginia wildrye,
under and outside mesquite canopy, were 247 and 329 kg ha-1, and 272 a
nd 268 kg ha-1, respectively. Dry matter production of green panic (p
= 0.001) and plains bristlegrass (p = 0.026) was greater under mesquit
e only for the first of four harvests, although both warm-season grass
es exhibited a trend for greater production under mesquite than in the
open. Average nitrogen content of green panic was greater (p = 0.0004
) under mesquite than in the open, while plains bristlegrass exhibited
a trend for greater crude protein content in the open than under mesq
uite. Overall, moisture content of the warm-season grasses was greater
(p - 0.0001) under mesquite than in the open, while Virginia wildrye
was more (p = 0.002) succulent under mesquite than in the open. Averag
e in-vitro dry matter digestibility of warm-season grasses was almost
significantly greater (p = 0.0501) in the open than under mesquite. Ca
nopy soils contained significantly more organic C (p = 0.0004) and tot
al N (p = 0.0001) than open soils, with differences of 8.3 Mg organic
C ha-1 and 1.3 Mg total N ha-1. Correlations indicated that soil ferti
lity was more limiting to grass production than light intensity.