103
Winter Small Grains Cover Crop Following Potatoes
R.L. Dovel, K.A. Rykbost, G. Chilcote and J. Rainey'
INTRODUCTION
Soil loss due to wind erosion is a major obstacle to sustained
agriculture in the Klamath Basin. Light soils and high spring winds
provide conditions for substantial soil loss in this region. To ensure
the continued productivity of highly erodible soils, federal farm programs are requiring greater erosion control on these soils. The local
SCS office has determined that residue covering 33 percent of the soil
surface will provide sufficient cover to prevent substantial soil loss.
The amount of crop residue left following potato harvest is minimal.
Vines are often burned to reduce over-wintering pathogens. A cover
crop is needed to protect the soil through the winter and especially
during the spring following potato harvest. The highest erosive wind
energy is received in April in the Klamath Basin.
A small-grain cover crop is one of the most effective methods for
erosion control. The cost of erosion control could be minimized if the
cover crop could also produce a marketable grain or forage crop. While
small grains are an important component of cropping systems in the
Klamath Basin, most of the grain planted is sown in the spring. This
project was conducted to identify species and varieties of winter
grains that are adapted to this region. Screening should include both
forage and grain yield as well as the ability to provide adequate soil
protection.
PROCEDURES
Trial I - Drilled Variety Trial
Two wheat varieties, four barley varieties and one variety each of
oats, cereal rye and triticale were planted at the KES on October 25,
1988. Plots were 5 feet wide and 40 feet long. Seed was planted 1 inch
deep with rows 6 inches apart at a rate of 30 seeds per square foot,
which corresponds to roughly 100 lbs/A for wheat, barley and triticale
and 85 lbs/A for rye and oats. Three harvests were made: one to
monitor biomass accumulation and ground cover for the prevention of wind
erosion; one when most of the cultivars were in the boot stage, to
assess forage production; and one after complete grain fill to measure
grain production. Fertilizer was banded at planting at a rate of 50 lbs
N, 60 lbs P205, and 44 lbs S/A. No chemical weed treatment was applied.
1/ Assistant Professor, Superintendent/Associate Professor, Research
Technician, Biological Sciences Research Technician, respectively,
Klamath Experiment Station.
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Trial II - Broadcast Trial
Immediately adjacent to the trial described above an unreplicated
trial including cereal rye, Hill '81 wheat, Boyer barley and Winter
Grey oats was established by broadcast seeding immediately prior to
potato harvest in the fall of 1988. Seed was broadcast at approximately
80 lbs/A. Each entry was broadcast over an area measuring approximately
20 x 200 ft. Seed incorporation was accomplished by the potato harvesting operation. Harvest procedures and dates were identical to Trial I.
Four sub-samples were taken from each plot and means given as an
estimate of yield.
RESULTS
Trial I
Rye provided the greatest amount of ground cover; however, all
species in the study provided adequate ground cover to prevent wind
erosion by mid-May (Table 1). Both barley and triticale produced an
average of 0.8 tons dry matter/A, significantly higher than winter oats
and Weston wheat. The prostrate growth habit of Flora triticale tended
to provide a greater amount of ground cover with an equivalent amount of
biomass.
Over the two-year period of the trial, cereal rye produced the most
hay followed closely by barley (Table 1). The two wheat varieties
included in this study produced less hay than either cereal rye or
barley. Triticale yielded similarly to barley and oat hay yields were
significantly lower than all other small grains included in the study.
No significant difference was observed in hay yield between varieties of
wheat or barley.
Grain yields of wheat and barley were very similar, averaging about
2.5 tons/A. However, Hill '81 produced significantly higher grain
yields than Weston. The use of Hill'81, a soft white winter variety,
would be more easily incorporated into current grain handling systems
than Weston, a hard red winter wheat. Winter and spring soft white
wheats may be handled simply as soft white wheat, whereas winter and
spring hard red varieties must be handled as separate classes.
Significant differences in grain yield between barley varieties were
also observed. The lowest yielding variety was Maury, a hooded winter
barley. This variety produced the largest amount of forage and has the
advantage of being awnless, which would greatly enhance its value as a
hay variety; however, due to the low yields seen in this trial it would
not be recommended as a grain variety for the Klamath Basin. Hesk
achieved the highest yield of grain in the study, with Scio and Boyer
averaging roughly 800 lbs/A less than Hesk. Seed of all three of these
varieties is readily available in Oregon and any one of them would be a
good choice as a winter cover crop/grain variety for the Klamath Basin.
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Grain yields of triticale were significantly lower than either wheat
or barley in 1988; however, triticale yields in 1989 were very close to
those of wheat and barley. Outstanding yields of winter triticale in
other areas and an increasing demand by poultry producers warrant furer consideration of this small grain as a winter cover/grain crop in the
area.
Rye grain yields were significantly lower than wheat or barley in
both years of the study. Due to lower yields, greater difficulty in
marketing this commodity and the potential for undesirable volunteers
when using this species, it is not a good candidate for grain production
following potatoes.
Both forage and grain yields of oats were significantly lower than
any other small grain in the study due to poor winter survival. Therefore, the use of oats as a cover crop is not recommended where spring
growth is important In contrast, all other grain commodities produced
adequate levels of ground cover in early spring and acceptable yields of
both forage and grain. Depending on the objectives and management conraints of the producer, cereal rye, triticale, barley or wheat can produce adequate ground cover to prevent or reduce wind erosion in the
early spring and provide a viable crop of either hay or grain.
Trial II
Broadcast plots were seeded and incorporated by potato harvest one
week prior to seeding drilled plots. Plants emerged earlier in the
plots which were broadcast seeded than in plots which were drilled, and
broadcast seedlings were larger than drilled seedlings at snow cover in
December. Growth in early spring was more rapid in broadcast than in
drilled plots, resulting in better ground cover by mid-April. Forage
production of broadcast plots was roughly equivalent to drilled plots.
However, plants in the broadcast plots reached soft dough stage earlier
than those in drilled plots. Broadcast seeding also produced similar
grain yields as drilled seeding and plants were slightly earlier
maturing in broadcast plots.
Though these results are not replicated and comparisons are not
statistically validated, it appears that broadcast seeding of small
grains prior to potato harvest will result in similar or better levels
of ground cover for erosion control and similar yields of forage or
grain as drill seeding. Due to time constraints during potato harvest
and unfavorable weather conditions in the fall, drill seeding of cover
crops will not always be accomplished. Broadcast seeding prior to
harvest is an alternative that should provide a more feasible means for
establishment of a small grain cover crop following potatoes than drill
seeding. Further study is needed to confirm the trends seen in this
preliminary trial.
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Table 1. Summary of Winter Grains Cover Crop Trial, 1987-1989.
Observations of ground cover, forage yield and grain yield
of winter grains seeded as cover crops following potatoes
at the Klamath Experiment Station.
Ground
cover
Forage yield
AVG
1988
1989
Tons/acre Grain yield
1988
AVG
1989
lbs/acre
Cereal Rye
Rheidel
1.7
4.4
3.0
3.7
3160
5242
4201
Triticale
Flora
0.8
2.8
3.6
3.2
2644
6092
4368
Winter Grey
0.5
2.7
2.2
2.4
1378
0
689
Hill 81'
Weston'
0.6
0.4
2.4
2.6
3.4
4.0
2.9
2.8
4292
3453
7211
5468
5751
4460
AVG Wheat
0.5
2.5
3.7
2.8
3872
6337
5104
Barley
Scio
Hesk
Boyer
Maury'
0.8
0.8
0.8
0.9
2.6
3.2
2.9
3.8
4.1
3.9
4.0
4.0
3.3
3.5
3.4
3.9
4162
5674
5267
4155
6767
6770
5421
2854
5464
6222
5344
3504
0.8
3.1
4.0
3.5
4814
5453
5133
0.7
29
0.3
3.0
30
1.2
3.6
14
0.7
3.3
13
0.6
3798
21
1003
3972
21
1213
4445
18
985
Oats
Wheat
AVG Barley
Mean
CV(%)
LSD(0.05)
'/Soft white winter wheat
2 /Hard red winter wheat
3 /Hooded winter barley