- A field experiment under irrigation was conducted at the
Hyslop Agronomy Farm, near Corvallis, Oregon, during the 1967
growing season to evaluate the effect of barley row spacing, nitrogen
rate and placement, and weed competition in the year of seeding upon
birdsfoot trefoil (Lotus corniculatus L.) seedling establishment.
The effect of birdsfoot trefoil on barley grain production was also
Three herbicides were used to measure the effects of weed
competition upon birdsfoot trefoil establishment and barley grain
production. These are: Avadex BW 1.25 lb. ai. per acre, 2, 4-DB
amine 1.50 Ib. ai. per acre and DNBP amine 1.50 lb. ai. per acre.
The effects of nitrogen in birdsfoot trefoil establishment and
on barley grain production were studied using two systems of placement:
80 lb. N per acre broadcast and 20 lb. N per acre applied in rows spaced at 7 inches plus 60 lb. N per acre broadcast.
The effects of row spacing on birdsfoot trefoil establishment
and barley grain production were determined using five systems of
seeding: (1) barley seeded alone in rows spaced at 7 inches, (2)
barley seeded alone in rows spaced at 14 inches, (3) barley seeded
in rows spaced at 7 inches plus birdsfoot trefoil seeded at the same
time in the same row, (4) barley seeded in rows spaced at 14 inches
plus birdsfoot trefoil seeded at the same time in the same row and in
row between barley, and (5) birdsfoot trefoil seeded in rows spaced
at 7 inches.
It was concluded that the use of a barley companion crop to
establish birdsfoot trefoil decreases the vigor of the trefoil; however,
the number of plants per foot of row was similar to the other
treatments. At constant seed rate of barley, an increase in row
spacing above 7 inches gave a decrease of grain yield and an increase
of dry matter yield of birdsfoot trefoil. Birdsfoot trefoil seeded
alone gave the highest dry matter yield in the year of establishment.
The trefoil did not affect the yield of barley.
Application of nitrogen as urea reduced the number of plants
of birdsfoot trefoil, when this species was seeded alone or together
with barley, but the yield of the forage species was not reduced.
Nitrogen application of 80 pounds per acre increased barley grain
yield when it was applied broadcast, but not when it was split into 20 pounds nitrogen per acre in rows at seven inches and 60 pounds
nitrogen per acre broadcast.
An interaction between 2, 4-DB application and nitrogen placement
was found in barley grain production, but not in birdsfoot trefoil
establishment. Also, an interaction between 2,4-DB application
and system of seeding was found to affect yield of dry matter of
birdsfoot trefoil. 2, 4-DB increased birdsfoot trefoil yield and
effectively controlled red root pigweed (Amaranthus retroflexus L.),
common lambsquarter (Chenopodium album L.), common groundsel
(Senecio vulgaris L.), and shepherdspurse (Capsella bursa-pastoris
(L.) Medic.), but it did not influence barley grain yield and the
number of plants of birdsfoot trefoil per foot of row.
DNBP had a detrimental effect on barley yield and was similar
to no herbicide on birdsfoot trefoil dry matter yield. It provided
good control of common groundsel and shepherdspurse, and gave a
poor control of red root pigweed and common lambsquarter.
Avadex BW was applied to control wild oat; however, this
weed was not present.