SOYBEAN PRODUCTION IN KENTUCKY PART I:
STATUS, USES AND PLANNING
ISSUED: 1-88
REVISED:
James H. Herbek and Morris J. Bitzer
Department of Agronomy
Status and Trends
Soybeans have emerged as a major crop
in Kentucky. As late as 1960, the Kentucky crop was valued at less than
$10 million. However, by 1979, soybeans were valued at over $300 million
and accounted for more than 20% of the total value of all crops produced
by Kentucky farmers. Despite recent price and production fluctuations,
soybeans continue to rank as one of Kentucky's 4 major crops in value of
production. Since 1980, soybeans have accounted for 13-18% of the total
crop value in Kentucky with an average annual value of almost $250 million.
Compared to other crops in the state,
soybeans' change from minor to major crop status came about quite rapidly
(Table 1). Within 20 years (from the late 1950s to the late 1970s) soybean
acreage increased over 700% and production increased over 1000%. With less
than 5% of the acreage in 1950, soybeans now comprise between 35-40% of
Kentucky's total grain crop acreage. The most rapid increase in acreage
occurred between 1970 and 1980 when it increased over 100,000 acres/year.
Soybean yields have increased less
dramatically. Table 1 indicates that yields actually decreased in the early
1980s. However, several droughts occurred during this period and if two
of the worst years are disregarded, state yields averaged over 30 bu/acre.
Since the early 1950s, yields have increased by 90%, averaging an increase
of .5 bu/acre/year, less than the average yield increases of other grain
crops during this time.
Several reasons exist for the slower
increase in soybean yields: 1) Soybeans were not treated as a major
crop; 2) rapid acreage increase often relegated soybeans to less
productive land; 3) rapid acreage increase resulted in "first-time"
growers unfamiliar with soybean production; 4) soybean technology
did not keep pace with the rapid increase in soybean acreage; and 5)
a good portion of Kentucky's soybean crop is double-cropped, resulting
in late-plantings which have a reduced yield.
However, the situation has changed
in the last 5-10 years. Soybeans are being treated as a "first-line" crop,
new growers are becoming more familiar with them and production technology
is being more readily adopted. With present production technology, state
average yields could be increased to 40-45 bu/acre. In fact, some Kentucky
producers have already achieved over 70 bu/acre in official yield contests.
Continued acreage expansion is also possible. In 1977 Kentucky's potential
soybean acreage was identified at about 2.5 million acres, 1 million more
than is now being grown.
Presently, soybean production is centered
in western Kentucky. In 1985, 82% of the acreage and production occurred
in Kentucky's 26 westernmost counties. However, soybean production is gradually
expanding into central and eastern Kentucky. Whereas in 1970 only 5% of
Kentucky's soybeans were grown in central Kentucky, in 1984 this portion
expanded to 13%.
Early use of soybeans all over the
US was for forage or hay and, to some extent, green manure. Not until the
early 1940s did the US acreage of soybeans grown for seed exceed that grown
for forage and other purposes. Presently the US produces over half of the
world's soybeans. Soybeans and soybean products are among the leading US
agricultural export commodities. From 40-50% of all US soybeans have been
exported in recent years which means that 1 of every 2 acres of soybeans
depends on export markets. Exports of Kentucky soybeans and soybean products
were valued at $120 million in 1985.
Table 1. Five-year Averages of Soybean Acreage, Yield and Production
in Kentucky Since 1935.
5-Year Period |
Harvested Acreage |
Yield (Bu/Acre) |
Production
(Million Bu) |
1935-39 |
10,800 |
10.9 |
.12 |
1940-44 |
58,600 |
12.5 |
.73 |
1945-49 |
97,400 |
17.8 |
1.73 |
1950-54 |
122,000 |
16.4 |
2.00 |
1955-59 |
151,000 |
21.2 |
3.20 |
1960-64 |
219,000 |
23.6 |
5.17 |
1965-69 |
381,200 |
26.3 |
10.03 |
1970-74 |
825,800 |
26.8 |
22.13 |
1975-79 |
1,302,000 |
29.5 |
38.41 |
1980-84 |
1,556,000 |
25.8 |
40.14 |
1985-86 (2 yr.) |
1,200,000 |
33.0 |
39.60 |
Record Yield: 34.0 bu/acre in 1985.
Record Harvested Acreage: 1,660,000 acres in 1979.
Source: Kentucky Crop Reporting Service.
Crop Uses
The soybean is a versatile crop that
can be used for many purposes. Today it is grown almost exclusively as
a cash crop for its oil-bearing seed or bean which is then processed and
refined into many oil and meal products. However, soybeans can also be
grown for hay, silage, residue utilization, green manure crop and specialty
markets.
Oil Seed Uses (Cash Crop)
Oil-bearing seed crops, such as the
soybean, have always been in demand. As a result, the soybean has become
an important cash crop. After the seed of the soybean crop is harvested
and sold, it can be processed into various oil and protein products and
by-products with a multitude of uses.
Soybean seed provides 2 important food
components, fat in the form of oil and protein in the form
of meal. Both components are derived at a per acre rate that exceeds most
other oilseed, food grain and feed grain crops. Soybean seed contains an
average of 20% oil and 40% protein. One bushel (60 lb) of processed soybeans
typically yields 47-48 lb of high protein meal and 11-12 lb of oil. However,
there can be considerable variation around these averages. The value of
a bushel of soybeans is determined by the combined values of the oil and
meal products. Different market factors will affect the values of the soybean
products and as their values change, so will the value of soybeans.
Most soybean seed is processed for
its oil. The seed can be processed and refined to remove the oil so that
both the oil and meal are of suitable quality. The primary product remaining
after oil extraction is soybean meal, which is high in protein.
Oil products and uses--Soybean
oil is the most important source for fats and oils in the world market.
In the US most of the soybean oil (90%) goes to the edible oil market and
the rest is used in animal feed and industrial products. Edible products
of soybean oil include salad and cooking oils, baking and frying fats and
margarine as well as other food products. Industrial uses include lubricants,
fuel, cements, printing ink, pesticide carriers, dust suppressants, paints,
soaps and lacquers.
Protein products and uses--The
soybean's nutritive value ranks the highest of all plant proteins. In the
US the majority of the protein products are used in animal feed and the
rest in edible food products. Soybean products, primarily meal, are used
in animal diets because of their low cost, high protein concentration and
widespread availability.
Although soybeans and soybean products
have been used as foods in oriental cultures for centuries, the western
world has just begun to recognize their importance for human food. Edible
protein products show promise as an expansive market for soybeans because
of their high quality protein, multitude of uses, and the development of
new processing, refining and manufacturing methods that will make these
products more acceptable to consumers. The soybean is one of the most nearly
ideal raw materials for developing new foods. It contains all the essential
amino acids, has no cholesterol, is high in unsaturated fat, and its milk
contains no lactose.
Four major types of soy protein products
are used for human food: flour and grits, protein concentrates, protein
isolates and textured proteins. These all differ from each other in protein
content, and in physical and chemical properties. Soybean products can
be found in many foods including baked goods, soups, baby foods, beverages,
cereals, snack foods, confectionary products, dairy products, meat product
extenders or analogs, and as milk substitutes.
Many nutritious and economical foods
can be prepared directly from soybeans or their raw products. Although
these foods have been common in the Orient for centuries, they are relatively
new to the US. Typical of such foods prepared by fermentation of soybeans
are soy sauce, natto (oriental delicacy), and tempeh (vegetative hamburger
alternative). Traditional unfermented soybean foods are fresh green soybeans,
soybean sprouts, soynuts (roasted whole soybeans), soy milk, soybean flour
and tofu (bean curd).
Since the soybeans grown in Kentucky
are produced primarily as a cash crop for oil seed uses, the production
and management topics discussed in this 5-part series will relate to producing
soybeans for this purpose. However, a brief discussion follows for each
of the soybean crop's other uses.
Soybean Hay
Soybeans have potential for hay production.
Although the acreage is small today, at one time the soybean crop was considered
more important for hay than grain. However, its low yield compared to other
crops used as forage, the development of a more profitable crushing market
for soybean seed in the 1930s and development of improved varieties and
production practices of superior forage crops led to the decline of the
soybean as a forage crop. Presently, soybean hay is usually grown where
another forage legume does not grow well, as an emergency hay crop or as
a method of salvaging a soybean crop if seed does not develop normally.
Any crop's value for hay production
is determined by its ability to produce digestible dry matter with an acceptable
level of crude protein. Thus, timing of harvest is important for best hay
quality. Soybean hay yields increase with time until the leaves start turning
yellow and dropping. The protein percentage in soybean hay does not decrease
with age as much as most forage plants, especially grasses, because of
the higher protein content in the developing seed. Although the protein
content of the leaves and stems decreases with maturity, the protein content
of the hay crop actually increases or remains constant because of the increasing
seed content.
Soybeans may be cut for hay over a
long period, from mid-bloom until the leaves begin to fall. The pod stage
is preferred for hay over the bloom stage because of higher dry matter
yields, higher crude protein digestibility, gross energy and digestible
energy. Late cutting is therefore better than early cutting. Some of the
more recent research indicates that, based on both quality and yield, the
best time to cut soybeans for hay is at mid to maximum pod fill and some
bottom leaves may be turning yellow (stage R6) but before leaf drop. Hay
harvested from green, well-podded soybeans will have from 15-20% crude
protein and 50-60% total digestible nutrients. An average yield of soybean
hay is about 2 tons/acre with 3 tons/acre or more under ideal growing conditions.
Because the soybean plant's most digestible and nutritive parts are the
beans, pods and leaves, harvest should occur before serious leaf deterioration
and drop.
As plants mature, the stems become
coarser and may cause feeding preference problems. Thus, harvesting should
not be delayed much beyond the best time for quality. Soybean hay is more
difficult to cure because the thicker stems dry more slowly. If used as
hay, soybeans should be dried adequately to avoid spoilage in storage.
The hay should be cured to 20% moisture before baling. A common practice
is to cut with a mower, cure in a swath and windrow. Use of a hay conditioner
will facilitate curing.
Since soybean hay is rather coarse,
it does not keep as well and waste losses are increased if it is stored
outside. Large, round bales have been used successfully to store soybean
hay. A high density bale is desirable because it resists moisture penetration
better than a low density bale. However, compactness can also be undesirable
because livestock have trouble tearing the bale apart and coarse stems
can further limit feeding access.
Production practices that favor soybean
hay production include:
1.Use of a full-season variety
for your area to increase vegetative growth and hay yield. Some older hay-type
varieties, which are generally more viney and finer-stemmed, are still
available. However, research has shown most of the present-day, full-season
grain types do as well.
2.Plant at optimum planting
dates. Late plantings reduce vegetative growth and production.
3.Plant in narrow or solid rows
at higher seeding rates (11/2 to 2 bu/acre) to produce higher yields of
finer-stemmed hay.
Often under poor growing conditions
such as late plantings, early frost, drought and poor stands a soybean
crop intended for grain harvest is considered instead for a hay crop. In
these cases the producer should estimate yield potential for both soybeans
and hay, evaluate production costs and estimate harvesting costs and market
value for each before deciding what to do. Remember that soybeans are primarily
a cash crop and usually will return more as grain than hay.
Before soybeans are used for forage
(hay, silage, or residue), check for any restrictions on their use for
feed in relation to any chemicals (herbicides, insecticides, or fungicides)
used on the crop.
Soybean Silage
Soybeans can be used as a high protein
silage. Crude protein on a dry matter basis is higher (15-20%) than corn
(7-10%). Soybeans can also be planted later than corn. The biggest disadvantage,
however, is relatively low yields (5-8 tons/acre).
Any soybean varieties used for grain
production can be used for silage. As with a hay crop, the later the silage
is cut, the higher the yield and the better the quality. Total protein
and yield is highest when pods reach maximum fill, but digestibility may
decrease slightly. The best compromise for silage harvesting may be to
cut when the pods are 1/2-3/4 filled which is before lower leaves begin
to drop and before the stem begins to get woody and lower in digestibility.
When used for silage, soybeans should be wilted to 40 to 50% dry matter
before chopping. The silage material should be finely chopped.
Recently interest has been shown in
combining soybean silage with another crop, particularly grain sorghum,
as a drought resistant summer silage crop. The soybean-sorghum silage has
lower yields, greater costs per ton, lower feed conversion, is less palatable,
lower in TDN, and higher in fiber and protein than corn silage. Thus, this
combination is neither cost efficient nor of quality equal to corn silage.
However, if corn planting is delayed, or a temporary silage crop is needed,
or production occurs on droughty soils, the crop combination may be desirable.
Research experience has shown that
crop mixtures seldom yield more than the highest yielding crop of the combination
when grown alone. Growing two crops simultaneously also presents production
practice problems with competition between crops, seeding rates, fertility,
weed control and proper stage of harvest for each crop.
Soybean Residue
By-products of crop production, such
as soybean residue, are a source of large quantities of low-cost feed.
Residues are generally high in fiber, high in dry matter, moderate to low
in energy and low in protein, vitamins and minerals. Soybean residue contains
4-5% protein and 40-45% TDN. Material that ends up as tailings behind the
combine contains the most nutritious parts of the plant residue, but this
material is the hardest to collect. Dried stems are only 30% digestible
compared to 60% for the leaves. Pods are higher in protein and are the
best part of the residue. Soybean residue yields are generally one ton/acre
or less.
Several methods can be used to harvest
or utilize the residue for feed. Grazing fields is the most common
way of harvesting since it is usually the cheapest and requires less labor
and equipment. However, this method results in the poorest utilization.
Other methods consist mainly of mechanized harvesting for storage
either in the field or at other sites. These include trailing dump wagons
during combining, forage harvesters with flail pickups, stacking machines
and balers. Residues stored in big packages should be fed in a manner that
minimizes feeding losses.
Concerns about crop residue removal
are that it increases depletion of soil nutrients and organic matter and
increases soil erosion. Caution should be exercised for continuous removal
on sloping lands and where soil structural problems exist. Extensive removal
of residues on these soils will increase the problems. If crop residues
are continually removed on these soils, winter cover crops should be grown.
Green Manure Crop
Soybeans are considered an excellent
green manure crop for improving soil structure and providing fertility
as a preceding crop in a rotation program with other crops, such as corn.
Although green manure was used to some extent several years ago, it does
not fit well into the present-day intensive grain programs. Present-day
economics do not justify the value received from leaving the land idle
and growing a green manure compared to growing another cash grain crop
on that land. However, on poorly productive soils or acres that are idle,
growing green manure can improve the soil. Plowing soybeans under as green
manure can add significant amounts of organic matter and nitrogen to the
soil.
Specialty Markets
Presently the markets for specialty
soybeans are small and highly competitive but can be good and profitable
for those who can get and hold onto them. Specialty soybeans are in demand
from certain food manufacturers, primarily in the Orient, to make traditional
soybean foods such as tofu, natto, bean sprouts and soy milk. Manufacturers
of these foods prefer certain characteristics in soybeans to produce a
high quality product. Although all of the specialty food markets require
a clean, varietally pure, high quality soybean, other requirements will
differ depending on the soybean food product.
Special seed characteristics required
may include color, size and uniformity, carbohydrate content, protein content,
processed appearance and taste, or hilum and seed coat requirements. For
example, high-protein soybeans are preferred for the tofu market while
smaller seeded varieties are useful for the sprout market. Large seeded
varieties (vegetable types) are preferred for consumption as a vegetable,
for roasting or for cooking. A small seed size, colorless hilum, thin seed
coat and high carbohydrate content are preferred for natto.
Extra effort and care are required
to produce a high quality soybean for the specialty food market, but the
effort is compensated for by premium prices.
Presently, several universities and
seed companies are developing soybean varieties with unique characteristics
for specialty food markets.
Preproduction Planning
Several management decisions need to
be made before planting. Although they may not be directly involved in
the planting process, they will greatly affect the outcome of the soybean
crop. These planning decisions, which will have multi-year effects on soybean
production, include land selection, cropping systems, tillage systems and
irrigation.
Land Selection
Although land selection is only the
first step in a total management program necessary for profitable soybean
production, it is the basis on which to build better than average soybean
yields. Like other crops, soybeans are more likely to reach their yield
potential on soils with no rooting restrictions, high fertility and adequate
moisture. Thus, in general, first class soybean soils are deep or moderately
deep, well to moderately well-drained, medium-textured, fertile soils that
occur on level or gently sloping land where flooding, run-off and erosion
are minimal.
Although soils having these characteristics
have the greatest potential for maximum yields, profitable yields can be
obtained on soils with less than optimum conditions. However, as the characteristics
of soils selected for soybean production become less desirable, decreases
in yield should be expected. The desirable characteristics of a good soil
for soybean production are further discussed below.
Water-holding Capacity
Soils should have a moderately high
available water-holding capacity since soybeans require from 18 to 22 inches
of water for good growth and development, which is more than the average
growing season rainfall. Any deficit not met with rainfall must be recovered
from water stored in the soil. Compared to corn, soybeans have a higher
water requirement per bushel. Based on average yields, over 3 times as
much water is needed to produce a bushel of soybeans as to produce a bushel
of corn.
In addition to water needs during plant
growth, soybeans require more moisture for germination than corn. A soybean
seed has to absorb 50% of its weight in water for germination to start
while corn only needs to absorb 30% of its weight in water.
The soil's water-holding capacity is
particularly important during the plant's reproductive development. Moisture
stress during the stages of early flowering through early pod-fill can
reduce yields by decreasing pod numbers, seeds per pod and seed size. Also
any moisture stress before pod-fill is completed can limit nutrient uptake
and result in yield reductions. Medium-textured (loamy) soils have higher
available water-holding capacities than do fine-textured (clayey) or coarse-textured
(sandy) soils. Soils selected should have a relatively rapid water intake
rate and should be nearly level to gently sloping so water runoff is minimal.
Rooting Depth
Soybean soils should also have at least
3 ft of unrestricted rooting zone. The soil should be free of hardpans,
permanent high water tables, and extremely coarse-textured or fine-textured
layers. In a soil free of physical and chemical limitations, soybean roots
can penetrate to a depth of 5 ft and laterally from 2 to 2 1/2 ft. In addition
to natural soil limitations that restrict root growth, man-made restrictions
such as compaction or traffic pans can also restrict root growth. Compaction
often results from excessive use of tillage equipment when soils are too
wet. Any soil characteristic that restricts or alters the development and
distribution of soybean roots will have a detrimental effect on growth
and yield.
Drainage
Well or moderately well drained soils
are best suited for soybean production. Poorly-drained soils often have
problems such as flooding, a high water table or low oxygen levels, and
create late planting and adverse harvesting situations, any one of which
can reduce yields. On the other hand, excessively drained soils, either
those occurring on steep slopes or those with very rapid internal drainage,
may not supply enough water.
Soil Structure
Soils selected for soybeans should
have a relatively stable structure in the surface horizon. They should
not have suffered much erosion and have at least 1% or more organic matter
in the surface horizon. Surface soils low in organic matter and with poor
structure tend to form crusts as they dry after heavy rains, which can
hinder the soybean seedling's emergence. The result is usually reduced
stands and yields.
Because soybeans leave a small amount
of easily-decomposed residue (about 3000 lb/acre), land on which they are
grown is more vulnerable to erosion. For this reason, land with slight
to no erosion hazard is best for soybean production. When soybeans are
grown on erosion-prone upland soils, conservation tillage practices should
be followed to control erosion.
Cropping Systems
Soybeans can be used advantageously
in many cropping systems and rotations involving the major grain crops
(corn, grain sorghum, and small grains) in the state as well as some of
the forage crops. The sequence of crops before and after soybeans affects
each crop's productivity. Studies in several states, including Kentucky
(Table 2), have shown that corn following soybeans yield 5-15% more than
corn following corn. Soybeans following corn have also yielded more than
soybeans following soybeans.
Why do rotations improve yields? 1)
Soybeans often provide some nitrogen for the following crop. 2)
Sound rotation systems help control nematodes, diseases, insects and weeds.
With any cropping rotation sequence, the grower needs to be aware of rotation
restrictions concerning herbicide use and carryover to the following crop.
Economics often dictate crop sequence
but where choices are available, soybeans should follow crops other than
soybeans or other legumes. Continuous cropping with soybeans is generally
not recommended because weed, disease, insect and nematode problems can
build up and significantly reduce yields. Although it may be difficult
because of land availability and other factors, growing soybeans no more
than 2 years in succession is probably best for successful production.
Typical rotations in Kentucky include:
1) corn-soybeans, and 2) corn-wheat or barley-soybeans (double-cropped)
which provides for 3 acres of grain production on 2 acres of land every
2 years. In this last system, after corn harvest, wheat or barley is seeded.
Following small grain harvest, soybeans are immediately planted. This rotation
is completed by growing corn following the soybean crop.
Table 2. Effect of Rotation on Crop Yields.
Previous Crop |
Yields (Bu/Acre)*
|
Soybeans |
Corn |
Soybeans |
37 |
146 |
Corn |
41 |
137 |
Rotation Advantage |
+4 |
+9 |
*Data for each crop has been averaged over several years.
Tillage Systems
Many tillage systems, involving different
tillage and planting equipment, can be used to prepare soil for planting
soybeans. Methods ranging from complete tillage (conventional) to reduced
tillage and no-tillage can be successfully used, but different methods
are best for different situations. Since fuel, labor and equipment expenses
are involved, tillage should be performed for a specific reason. It has
been said that proper tillage is the least tillage necessary to produce
the desired crop as efficiently as possible.
A tillage survey conducted in 1986
by the Kentucky Crop and Livestock Reporting Service indicated that of
the total soybean acreage planted, 54%, 20% and 26% were planted using
conventional tillage, minimum tillage and no-tillage, respectively. Conventional
tillage has been gradually reduced and conservation tillage planted soybeans
have increased during the last 15 years.
Seedbed Preparation
A good seedbed provides a favorable
place for seed to germinate and roots to get moisture and nutrients. Traditionally
soybeans have been planted in a seedbed that has been tilled several times.
However, you can do a good job of planting with a minimum of tillage and
it is false that the only good seedbed is a tillage prepared seedbed. Regardless
of the tillage system used, soybean seeds need a soil that is warm (65°F
or above), moist, well supplied with air, smooth, free of living weeds
and firm enough to give good contact between the seed and soil for uniform,
rapid emergence.
Conventional Tillage
The traditional tillage system for
soybeans consists of plowing with a moldboard plow in the fall or spring
followed by one or more secondary tillage operations. However, recent years
have seen more reduced tillage and fewer secondary tillage operations.
Primary tillage with the moldboard plow is being replaced by the chisel
plow and other subsurface tillage equipment. Primary tillage, if used,
should be only deep enough to perform required functions. Reasons for plowing
or heavily tilling a soil for soybeans are: 1) removal of residue
to increase soil temperature; 2) to improve air or water movement
in wet, fine-textured soils; 3) weed control; 4) leveling
or smoothing land; 5) removal of compacted layers; and 6)
insect and disease control.
No-tillage
No-tillage soybeans have gained acceptance
in the state, particularly with double-cropping where it provides a timely,
efficient method of planting. In 1986, 85% of the double-cropped soybean
acreage was planted using no-tillage.
No-till soybeans have many advantages:
1) soil erosion control; 2) better maintenance of soil tilth
and productivity; 3) soil moisture conservation; 4) less
energy and labor required;
5) reduced costs of production; and 6) yields equal to
or higher than conventionally planted soybeans (Table 3).
No-tillage does require a more intense
level of management. With fewer alternatives to correct errors, more management
ability is needed for no-till to be successful.
Soybeans have been successfully no-tilled
into various crop residues (small grains, corn, grain sorghum and soybeans)
and winter cover crops. However, no-till planting of soybeans into a perennial
grass or legume sod is presently limited in Kentucky. This system has presented
more risks since herbicides for no-till soybeans in sod have not been as
successful and consistent as desired. For more information on no-tillage,
get a copy of AGR-101, No-till Soybeans, from your local county
Extension office.
Table 3. Yield Comparisons of Tillage Systems for Soybeans in Kentucky.
Tillage System1 |
Soybean Yield (Bu/A)
|
1968-692 |
1976-783 |
1980-852,3 |
No-till - S.C. |
42 |
|
36 |
Minimum-till - S.C. |
|
|
36 |
Conventional-S.C. |
39 |
|
35 |
No-till - D.C. |
|
35 |
27 |
Minimum-till - D.C. |
|
35 |
26 |
Conventional - D.C. |
|
33 |
24 |
1S.C. = single-crop and D.C. = double-crop.
2Planted following previous crop residue.
3Planted following wheat stubble.
Irrigation
Average annual rainfall in Kentucky
of approximately 45 inches would indicate irrigation is not needed. However,
this rainfall is not evenly distributed throughout the year and quite often
is insufficient during the growing season when soybean peak water usage
can reach 1 to 2 inches/week. This peak moisture usage period occurs during
flowering and pod fill.
Presently, only a limited number of
acres of soybeans are irrigated; however, interest has increased somewhat
in recent years. The major reasons for the limited irrigation in Kentucky
are lack of a readily available water supply and the erratic yearly rainfall
patterns.
Studies are assessing the short and
long-term economics of soybean irrigation in the state (Table 4). Data
from 1980-86 readily show the economic importance of irrigation during
years when moisture shortages existed during the growing season. In other
years, irrigation would not be profitable. The average yield response achieved
for the 6-years would be marginally profitable depending on irrigation
costs and soybean prices. Therefore, it is difficult to determine whether
an irrigation system used only for soybeans would be economically profitable.
If irrigation were used for other crops such as corn, soybean irrigation
would appear more feasible since the investment would be spread over several
crops.
Table 4. Soybean Irrigation Results1
Year2 Response |
Soybean Yield (Bu/A) |
Non-irrigated |
Irrigated |
Yield |
1980 |
31 |
43 |
+11 |
1981 |
67 |
71 |
+4 |
1982 |
60 |
63 |
+3 |
1983 |
9 |
59 |
+50 |
1984 |
44 |
56 |
+12 |
1986 |
32 |
52 |
+20 |
Avg. |
41 |
57 |
+16 |
1Research and Education Center - Princeton, Ky.
21983 = prolonged moisture stress.
1980, 1984, 1986 = periods of moisture stress.
1985 = no data due to hail damage.
Suggested References and Related Publications
University of Kentucky Publications
AGR-91, Cropland Rotations in Kentucky
AGR-101, No-Till Soybeans
AGR-129, Soybean Production in Kentucky-Part II: Seed Selection, Variety
Selection and Fertilization
AGR-130, Soybean Production in Kentucky-Part III: Planting Practices
and Double-Cropping
AGR-131, Soybean Production in Kentucky-Part IV: Weed, Disease and
Insect Control
AGR-132, Soybean Production in Kentucky-Part V: Harvesting, Drying,
Storage and Marketing
4BB-04PO, Kentucky 4-H Soybean Project
ID-9, Salvage Feeds for Beef Cattle
OPTIONS-1O, Options for Kentucky Farmers-Soybeans
Other Publications
Modern Soybean Production (Available from American Soybean Association,
St. Louis, MO) (For sale only)
Soybean Irrigation (multi-state publication) (Available from Mississippi
State University, Miss. State, MISS) (For sale only)