Intercropping Oat Hay and Annual Legumes
R.L. Dovel, J. Rainey, and G. Chi'cote'
Introduction
Oat hay is a valuable forage commodity in the Klamath Basin. An
increasing acreage of oat hay is being produced in the basin due to rising hay
prices and declining grain prices. The possibility of water shortages is also
fostering increased interest in cereal hay production. In trials at KES, oat and
hooded barley hay harvested at the soft dough stage averaged 38 and 39
percent total digestible nutrients (TDN) and 8.9 and 9.6 percent crude protein
(CP), respectively. Oat hay CP concentration usually ranges from 6 to 10
percent in the Klamath Basin and TDN content may be less than 35 percent.
Forage quality of cereal hay is generally lower than is required to meet
production goals for many livestock classes. Interseeding annual legumes into
small grains has increased both forage production and quality across a number
of environments. The possibility ofprolonging the growing season past the
cutting date for the small grain hay crop is an additional advantage in a forage
production system. It provides for additional production when irrigation or
timely rains make additional production possible.
Annual forage legume variety trials have been conducted at KES over
the past three years. In 1992 and 1993, legumes were planted in monoculture and total biomass production and forage quality were monitored. Several
annual medic, field pea, and clover varieties showed promise for interseeding
in oats for hay. Several entries produced more dry matter than Austrian winter
peas, the most common legume currently used in oat-legume mixtures. Some
fall regrowth was seen in plots interseeded with annual medic species; however, regrowth ofberseem clover entries was roughly twice that of annual
medic entries. Further testing of annual forage legumes is needed to determine
which is appropriate for inclusion in a small grain-forage intercropping system
in the Klamath Basin. A trial to evaluate annual legumes for interseeding in
oats for hay was established at the Klamath Experiment Station in 1994.
'/ Associate Professor, Biological Sciences Research Technician III, and Research Technician,
respectively, Klamath Experiment Station, Klamath Falls, OR.
160 Klamath Experiment Station
Intercropping Oat Hay and Annual Legumes
Procedures
The trial was arranged in a randomized complete block design with four
replications. Oat seed was sown to a depth of one inch with a modified
Kincaid planter. Plots were fertilized with 50 lb N, 62 lb P 2 0 5 , and 37 lb S/
acre in a band application at planting. Seed of the forage species was broadcast using the same drill and incorporated by light raking. Plots measured 5 x
20 feet with a barley row spacing of six inches. The crop was sprinkler
irrigated by a solid set irrigation system.
Forage was harvested when oat plants reached the soft dough stage.
Prior to harvest, plots were trimmed to 17 feet long. The crop was harvested
using a flail harvester with a three-foot wide head. All yields were reported
on a dry weight basis. Subsamples were collected and analyzed for forage
quality, acid detergent fiber (ADF), neutral detergent fiber (NDF), crude
protein (CP), and relative feed value (RFV) using a near-infrared reflectance
spectrophotometer (NIRS). Fall herbage production was monitored as well.
No chemical weed control was applied and weed population density was
monitored. All data collected were analyzed by analysis ofvariance procedures.
Results and
Discussion
Interseeding forage legumes into oats for hay at KES did not affect
forage production (Table 1). However; interseeding with four different legume
entries (Austrian winter peas, Maple peas, Magnus field pea, and Ascot
barrel medic) produced significantly higher CP levels than the non-interseeded
control. Only Austrian winter peas produced significantly lower ADF and
NDF values than the control. Similarly, only Austrian winter peas produced
significantly higher RFV than the non-interseeded control. Although Magnus
field pea and maple pea produced significantly higher yields than Austrian
winter pea when grown in monoculture in 1993 and 1992, there was no yield
or quality advantage of any entry over Austrian winter pea when grown in an
oat-legume mixture. Fall regrowth following cutting was visually monitored
and only Multicut berseem clover produced significant regrowth. Barrel
medic, burr medic, and snail medic entries had set seed and were senescing
due to their determinate growth habit. Although they were green, black
medic, sub clover, and rose clover entries did not regrow following cutting.
Klamath Experiment Station 161
Intercropping Oat Hay and Annual Legumes
This may have been due to drought stress or, in the case of sub clover, it may
have been due to low fall temperatures. Where fall growth following hay
harvest is important, berseem clover may be the best choice. It produced
forage yields and forage quality equivalent to Austrian winter pea and produced the best fall regrowth.
This trial was well irrigated and moisture stress did not limit production.
The results ofthis trial are applicable to irrigated highly productive situations.
In areas and management systems where moisture would limit plant growth,
more drought resistant legumes such as the annual medics may be more
productive than the pea varieties included in this trial. Additional data is
needed to confirm the findings of this first year of testing.
162 Klamath Experiment Station
Intercropping Oat Hay and Annual Legumes
Table 1.
Forage yield, crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF),
and relative feed value (RFV) of oat-legume mixtures planted at Klamath Experiment
Station, OR, 1994.
Variety
RFV
Yield
CP
ADF
NDF
tons/A
(%)
(%)
(%)
Ascot Barrel Medic
Boning Barrel Medic
Caliph Barrel Medic
Mogui Barrel Medic
Parrabinga Barrel Medic
6.07
6.05
6.45
5.57
6.69
8.6
7.8
8.1
8.4
7.1
39.3
40.2
39.8
41.0
42.0
55.1
56.8
56.1
58.4
60.3
99
95
97
91
87
Parraggio Barrel Medic
George Black Medic
Santiago Burr Medic
Sava Snail Medic
Berseem Clover Multicut
6.19
6.06
5.75
6.41
6.40
8.3
7.3
7.2
7.7
8.3
38.9
40.2
42.3
39.0
37.7
55.7
58.7
59.8
55.9
55.1
99
91
87
97
101
Clare Sub Clover
Karridal Sub Clover
Monte Frio Rose CLover
Overton Rose Clover
TnIckala Sub Clover
6.43
5.84
6.46
5.96
6.89
6.2
7.7
6.7
6.3
7.4
41.4
38.5
39.7
42.4
38.4
59.8
56.1
57.9
61.2
55.9
89
98
94
85
98
Austrian Winter Pea
Magnus Field Pea
Maple Pea
Border Oats (control)
6.10
6.10
6.67
6.35
9.5
8.7
8.8
6.8
37.0
38.4
39.1
41.5
53.3
56.0
56.4
59.9
106
99
97
88
Mean
CV (%)
LSD (0.05)
6.23
12.1
NS
7.7
15
1.7
39.8
7.6
4.3
57.3
7.2
5.9
95
11.8
16
Klamath Experiment Station 163