Alflfa-Oat-Clo rer Pasture for Dairy Cattle


 Calculated production costs of unirrigated pastures ranged
from $61 to $89 per acre for different years and averaged $70.50
per acre annually. Production costs of total digestible nutrients
derived from unirrigated pastures averaged 1.54 cents per pound.
Calculated annual feed replacement value of pasture per acre
averaged $206, and the net return $135.50 per acre.
 Annual production costs per acre, excluding irrigation ex-
penses, averaged $63 for 1955-56 and 1956-57. Average annual
feed replacement value per acre of pasture for the two years was
$144 for the unirrigated and $214 for the irrigated. The in-
crease in feed replacement value averaged $3.95 per acre inch
of water applied.

 DISCUSSION
 Alfalfa in combination with oats and clovers provided ex-
cellent pasture with an average annual yield of 4,585 pounds of
total digestible nutrients per acre obtained from unirrigated pas-
tures in four seasons. During two years when comparable
pasture plots were irrigated, averages of 1,023 and 2,017 pounds
more total digestible nutrients were obtained per acre from the
irrigated pastures during the respective grazing seasons. Graz-
ing was begun 14 and 51 days earlier on irrigated pastures dur-
ing the respective seasons, and the supply of feed from them
was more uniform. Irrigation did not improve quality of for-
age as indicated by growth response of heifers grazing the pas-
tures. The increase in calculated feed replacement value of
feed produced per acre inch of water applied averaged $3.95.
This value exceeds the commonly employed irrigation cost range
figures of $2 to $3.50 per acre inch for sprinkler type irrigation
and of $0.25 to $0.75 for subirrigation. Rainfall was subnormal
during the two years when supplemental irrigation studies were
made.
 Alfalfa furnished most of the forage during fall and winter
and practically all of the forage during spring and summer.
Oats furnished a significant but minor proportion of the graz-
ing in the fall and during mild winter. Oats usually grew more
rapidly than alfalfa, and stem joints frequently had formed by
the time animals were placed on the pasture. Grazing at this
growth stage impaired regrowth, and freezes following initial
grazings killed most of the oat stubbles during two seasons.
 Stands of clovers were poor due to overshading by the taller
plants. They produced very little forage except along the bor-