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Soil Management: A summary from KSU
circulars and bulletins from 1899 to1965
by
Lisa French
Contents: Soil Health; Decline of Kansas Soils; Soil
Organic Matter; Nitrogen and Organic Matter; Phosphorus;
Potassium; Calcium (Lime); Soil Bacteria; Analysis of
the Soil; Commercial Fertilizers; Crop Rotations; Wrong
Turns; Erosion Control; Western Kansas Cropping Systems;
Fallow; Organic Matter Content of Western Kansas Soils;
Looking to the future of Kansas soils; Sources.
The practice of sustainable agriculture is built upon
soil fertility and the protection of soil health. For
centuries, farmers around the world have been employing
these basic techniques to keep their soil productive.
Early in colonial American history, George Washington
was using cover crops and manure applications on his
farm. American farmers, who did not carefully tend their
soil, eventually "wore it out." The Westward
Expansion partly reflected the lowered productivity
of eastern lands and the search for new farmland farther
west.
The first publications from the Kansas State Agricultural
College appeared in the late 1880's, at a time when
Kansas soils had been tilled for less than fifty years.
Soil scientists were well aware at that time that the
long term sustainability of farming depended upon the
use of legumes for fertility and the addition of organic
matter for tilth. As Kansas farmers began to report
declining fertility levels in the early 1900's, scientists
cautioned that farmers must not rely solely upon the
natural fertility of the prairie soils.
Between 1900 and 1950, Kansas State researchers guided
farmers in the use of legumes and the preservation of
soil organic matter. With the advent of inexpensive
nitrogen fertilizers after World War II, traditional
soil management techniques took a back seat to the use
of commercial products that were easy to use and often
provided greater economic returns in the short-term.
At the beginning of the twenty-first century, farmers
are becoming increasingly conscious of the importance
of soil health, water quality, and energy conservation.
The rising cost of nitrogen fertilizers has revived
interest in nitrogen-fixing legumes. Excess phosphorus
levels in surface water indicate a need to emphasize
soil conservation and the careful use of manure resources.
Traditional soil management practices continue to be
vital for the sustainable agriculturist and are regaining
an audience with conventional agriculture.
This review of Kansas State University soil publications
profiles the research and recommendations of Kansas
scientists during the early to mid-twentieth century.
Generally, recommended practices such as crop rotations,
manure use, cover crops, and other sources of fertility
are considered including the shift to commercial fertilizers
in the 1950's. The special consideration of western
Kansas soils is treated separately. Limited rainfall
in western Kansas affects the research conducted in
that part of the state and alters the use of traditional
soil health practices.
Soil Health
Within every aspect of Kansas agriculture, healthy
soil is a key element. Its structure and fertility provide
the basis for all crop and livestock production. Throughout
the historical publications of Kansas State University
from the late 1800's to the mid-1900's, researchers
and educators have been concerned with the protection
of this vital resource.
In their 1918 publication, Soil Fertility, L.E. Call
and R. I Throckmorton caution the Kansas farmer. "The
soil is the most important source of wealth in an agricultural
state. If it is maintained in a high state of productivity,
by wise systems of soil management, the people prosper.
If its fertility is wasted through careless methods
of farming, both the farmer and the state suffer"
(1918, Soil Fertility, p. 3).
Forty years later, in 1956, Orville Bidwell echoes
this same message with its promise of a precarious wealth.
"Unlike most other resources, soil is inexhaustible
if properly managed." Bidwell recounts the variety
of Kansas soils each with a different waterholding capacity,
permeability, response to fertilizers, and susceptibility
to erosion. He emphasizes that the Kansas farmer must
understand the character of a particular soil in order
to best manage it as an "inexhaustible" resource
(1956, Major Soils of Kansas, p.3).
Decline of Kansas Soils
Throughout many of the earliest publications, the authors
are clearly concerned about the declining condition
of Kansas soils. By the early 1900's, much of the rich
prairie soil in eastern Kansas had been farmed for 50
years. A 1903 publication from the veterinary department
of the Kansas State Experiment Station states, "The
fertility of the soil of the Middle states and the West
is being rapidly diminished and if means are not taken
to prevent it, the time is not far distant when it will
be as necessary to apply artificial fertilizers to the
soil as it is now in the East" (1903, Bacteria
of the Soil, p. 167).
A few years later, chemists at the agricultural experiment
station raised the same concern. "In the early
history of Kansas no attention was paid to the composition
of its soils except to boast of their inexhaustible
fertility. The voice of the chemist has been lifted
constantly, warning the people that this idea of possession
of a fertility that is practically limitless is a delusion
that can lead only to squandering of our natural resources,
and to leaving posterity handicapped in the struggle
for existence. To-day he is seeing his warnings justified.
People in many localities of the eastern part of the
state are making inquiry concerning chemical analysis
of their soils with reference to learning what fertilizers
should be applied and to what crops their soils are
best adapted" (1910, Fertilizers and Their Use,
p. 57-58).
By 1918, L.E. Call and R. I. Throckmorton attempted
to put dollar figures to the losses in soil fertility.
They estimated that the plant food removed from Kansas
soils by wheat crops over the previous fifty-five years
equaled a value of more than seven hundred million dollars.
Even the wheat straw, which was regularly burned or
wasted, had a value in plant nutrients of more than
twelve million dollars. The majority of the wheat products
were both milled and eaten outside the state which Call
and Throckmorton equated with the export of soil fertility
(1918, Soil Fertility, p.3).
Call and Throckmorton credited the declining productivity
of Kansas soils to five factors: depletion of soil organic
matter, failure to grow enough acres of leguminous crops
for nitrogen fixation, depletion of mineral nutrients,
the lack of proper crop rotations, and the erosion of
fertile topsoil. These five factors are the subject
of nearly every soils publication prior to the advent
of inexpensive nitrogen fertilizers in the mid-1900's.
They continue to be the basis of soil health for every
farming system regardless of the use of commercial fertilizers.
Soil Organic Matter
The early Kansas State publications recognized the
importance of soil organic matter to soil health. Replenishment
of soil organic matter is the most basic step in addressing
a number of other issues. According to Call and Throckmorton,
organic matter holds the soil's store of nitrogen, provides
good tilth, holds moisture, and provides food for the
bacteria that make nutrients available to plants.
Soil studies in western Kansas spanning over 30 years
of crop production give mention to the importance of
organic matter. Progress reports in 1943 and 1957 indicate
that as the organic carbon content of the soil has decreased,
more power is needed for tillage, water intake is decreased,
seedling emergence and root growth are hindered. The
1943 report also mentions that the presence of coarse,
fibrous organic matter helped reduce wind erosion (1943,
Nitrogen and Organic Carbon Changes in Soils, p. 31
and 1957, Nitrogen and Organic Carbon Changes in Cultivated
Western Kansas Soils, p. 24).
Numerous publications cite frequent plowing and intensive
cultivation as culprits in the loss of organic matter.
Row crops depleted the soil more quickly than small
grain crops. Without a regular practice of restoring
organic matter, the levels of carbon in the soil would
drop, threatening fertility and soil structure.
The 1918 publication, Soil Fertility, promotes barnyard
manure applied to the soil as a primary source of organic
matter. However, when sufficient manure is not available,
the farmer should grow a crop to plow under to supply
organic matter. These green manure crops may be legumes
such as alfalfa, cowpeas, soybeans, clover, or sweet
clover. Legumes would capture atmospheric nitrogen and
fix it in the soil in addition to supplying organic
matter. Non-legume crops such as rye, buckwheat, sorghum,
and turnips were also cited as possible sources for
organic matter (1918, Soil Fertility, p. 21).
Although most of the methods for increasing organic
matter focus on the addition of green manure crops or
barnyard manure, the conservation of all organic matter
is addressed. Throckmorton and Call state that most
wheat straw is either burned or destroyed after threshing.
They recommend its use as feed and bedding for livestock.
Eventually the soiled bedding and any manure would be
returned to the soil. They also suggest use of the straw
as a surface mulch on wheat during the winter at a rate
of 1 - 1.5 tons per acre (1918, Soil Fertility, p. 20).
In 1962, farmers were again cautioned not to waste
the organic matter provided by straw or stubble. In
an effort to control weeds and increase yields, burning
of wheat stubble had become a common practice. A series
of studies in western Kansas produced data showing that
stubble burning did not increase yields for subsequent
crops. Not only did it present increased potential for
wind erosion, it also decreased the soil's ability to
absorb water (1962, Investigations of Cropping Systems,
Tillage Methods, and Cultural Practices for Dryland
Farming, p. 36).
Nitrogen and Organic Matter
The supply of nitrogen in the soil was closely linked
to the organic matter content. The practice of returning
organic matter to the soil in the form of leguminous
plants or animal manures was also the method for supplying
nitrogen prior to the use of commercial nitrogen fertilizer.
Legume crops, grown in rotation with other crops, could
be worked back into the soil as a green manure crops
or the legume hay crop was fed to livestock and their
manure was returned to the soil.
Off-farm sources of nitrogen in the early 1900's included
waste materials from the packing houses and inorganic
compounds such as saltpeter, which was mined in Chili,
and manufactured compounds of ammonium sulphate or calcium
cyanamide. Researchers noted that "the purchase
of nitrogenous fertilizers should be limited to the
meeting of special requirements of certain conditions
or crops...Nitrogen...is the (nutrient) most cheaply
restored, since by the cooperation of clovers, alfalfa,
peas, beans, and other legumes with bacteria that grow
upon their roots the abundant nitrogen of the air in
the pores of the soil is brought into organic combination.
This means of adding nitrogen to a soil must never be
lost to view..." (1910, Fertilizers and Their Uses,
p. 56).
Through the first half of the twentieth century, researchers
and farmers sought to understand the best methods for
capturing nitrogen with legumes especially when those
crops were being used for other purposes on the farm.
In 1918, researchers were concerned that the nitrogen
found within the crop roots and stubble might not be
significant compared with the amount removed in a hay
crop. They hypothesized that a certain amount of leaf
loss during the haying process might be returning some
nitrogen to the soil. Still they cautioned that the
best practice was to feed the hay on the farm and return
all manure to the soil (1918, Soil Fertility, p. 11).
The 1939 publication on fertility studies at the Manhattan
experiment station beginning in 1910 gave evidence that
soil nitrogen could be increased even when the hay was
removed. The average increase in the 5-9 year old hay
plots was twice that for the 1-4 year plots. The researchers
also found that the residual effects of the "nitrogen
accumulating capacity" remained for eight to nine
years following the breaking of the alfalfa sod that
had been in alfalfa for more than two years (1939, Nitrogen
and Organic Carbon of Soils as Influenced by Cropping
Systems and Soil Treatments, p. 24-25).
But nitrogen was not the only concern when hay was
taken off the farm. "If alfalfa is sold off the
land it is one of the most soil-exhausting crops raised,
while if it is fed on the farm, and the manure produced
applied to the land, it is a conserver of fertility.
The same argument applies to clover" (1914, Chemical
Analysis of Some Kansas Soils, p. 641). Potassium, phosphorus,
calcium and other mineral elements are taken up by the
plants and must be cycled back to the soil as green
manure or barnyard manure. When hay is sold off the
farm, the phosphorus and potassium are more rapidly
depleted than with a continuous grain crop.
Regardless of the use of green manure crops, any farm
with livestock had a source of organic matter and nutrients
in animal manure if it was used wisely. "If the
livestock farmer properly saves and utilizes his manure
he can maintain his soil in a high state of productivity,
but the livestockman who feeds his cattle in woodlots
along the banks of streams, and so wastes his manure,
usually depletes the fertility of his soil more rapidly
than the man producing grain only (1918, Soil Fertility,
p. 23-24).
It was important to manage manure so that nutrients
were not lost before they were cycled back to the soil.
The seepage of liquid waste or urine, leaching of manure
by rain and runoff water, and the "decay"
of manure solids and the subsequent loss of nitrogen
are all a result of poor handling techniques. Throckmorton
and Call recommend that the most practical method of
manure handling would be to feed the stock on the cultivated
fields so that the manure is scattered by the animals
and the nutrients are retained by the soil. In any case,
the manure should be returned to the soil as soon as
possible and long term, open storage of six months or
more should be avoided (1918, Soil Fertility, p. 24).
Manure could also be used sparingly as a top dressing
on corn, kafir, or winter wheat where it would act as
mulch to retain moisture. If there was not a large supply
of manure, it was deemed better to apply the available
supply lightly to more acres rather than a heavy application
on just a few acres (1918, Soil Fertility, p. 28).
As a percentage of volume, the nutrients present in
manure are small. "The figures for the fertilizing
constituents are always low, but they are present in
readily available form and the accompanying organic
matter has itself a highly beneficial effect on the
land. Even with these low percentages the total amount
of plant food in the manure produced on a farm reaches
very significant quantities" (1910, Fertilizers
and Their Uses, p. 77).
Phosphorus
Fertilizers were commonly used to provide phosphorus
and other minerals long before nitrogen fertilizers
were in general use. By 1918, the soils in eastern and
southeast Kansas had such low stores of phosphorus that
it was profitable to purchase phosphorus fertilizers.
Grain farms lost phosphorus the most rapidly when it
was exported off the farm with the grain. In order to
retain the mineral, the farmer had to feed the grain
to livestock and apply the manure to the croplands or
else import a supply of phosphorus (1918, Soil Fertility,
p. 10).
Alfalfa and other deep-rooted crops could be used to
collect phosphorus from the subsoil. The nutrients then
needed to be cycled back into the upper levels of the
soil as either a green manure crop or manure from animals
fed on the hay.(1918, Soil Fertility, p. 31).
Commercial sources of phosphorus included bone, basic
slag, rock phosphate, and apatite (1910, Fertilizers
and Their Uses, p. 54-55). Bones were a valuable product
rich in phosphorus and nitrogen. They could be ground
raw but they were more commonly steamed before grinding.
This processing made grinding easier, concentrated the
phosphorus slightly and increased the availability to
plants.
Basic slag was a by-product from a particular method
of iron refinement. Minerals removed from certain iron
ore contained high amounts of phosphate, which could
be ground for use as a fertilizer. This was not a common
product in America, being chiefly available in Europe.
Primary sources of rock phosphate were found in Florida,
South Carolina, and Tennessee during the early part
of the twentieth century. Although it was most often
used to produce superphosphate, it could be finely ground
and used raw. Superphosphate was produced by treating
the raw phosphate with sulphuric acid and was in use
to some extent throughout the twentieth century (1910,
Fertilizers and Their Uses, p. 54-55).
Although superphosphate was more readily available
to the plant, Kansas State researchers advised that
the raw phosphate was usually a wiser choice. "In
the application of phosphate fertilizers the farmer
naturally expects and desires immediate results, which
are secured by the use of superphosphate, but at the
same time if larger quantities of phosphates can be
applied in other less soluble and available forms at
the same expenditure, the ultimate value of the investment
may be much greater, as the phosphorus will remain in
the soil and be rendered available by slow natural processes
(1910, Fertilizers and Their Uses, p. 55).
There was also indicated a positive relationship between
the bacteria found in organic matter and the availability
of phosphorus from raw phosphate. "The cheapest
source of phosphorus is ground rock phosphate, and in
this form it will be available for the use of crops
if the soil is well supplied with organic matter from
farm manures and legumes (1914, Chemical Analysis of
Some Kansas Soils, p. 664).
Apatite, a crystal found in granite, was abundantly
available in Canada. It needed to be converted to superphosphate
to be used as a fertilizer.
Potassium
Potassium occurs in the mineral or rock portion of
the soil. Plant roots are able to access potassium directly
from tiny soil particles, chiefly silt and clay. Potassium
is also present in decaying crop residues and organic
matter, indicating the need, once again, for returning
plant materials to the soil (1918, Soil Fertility, p.
10). A traditional source of additional potassium was
hardwood ashes. Muriate of potash, a processed form
of potassium in wide use today, was also available early
in the twentieth century but due to the chlorine content
of the compound, its use was restricted with certain
crops (1910, Fertilizers and Their Use, p. 51-52).
Calcium (Lime)
Calcium, while an essential element for plant growth,
was usually not deficient in Kansas soils. However,
its application in the form of lime, was a common soil
amendment. "(Calcium) is generally present in all
cultivated soils in sufficient quantity to supply fully
the need of the plant. Yet even where this is the case,
the soil may be greatly in need of liming. Lime is used,
therefore, as a soil amendment not so much for its effect
directly on the plant as for its effect on the soil,
which indirectly affects the plant. Soils that are low
in lime are said to be sour" (1918, Soil Fertility,
p. 38). The acidity of these soils could be neutralized
by the application of calcium compounds.
A 1918 publication recommended two tons of ground limestone
per acre followed by one or two tons every five to six
years thereafter. The limestone should be worked into
the bare ground six months to a year prior to seeding
alfalfa or clovers. The effects of the limestone are
slow and gradual but long lasting. The bacteria that
live on the roots of alfalfa, sweet clover, and clover
thrive in more alkaline soils so these crops respond
well to liming. Crops considered less sensitive to acid
soils were corn, wheat, timothy, and oats (1918, Soil
Fertility, p. 38-40).
The change in soil pH improved the availability of
phosphorus and potassium as well as improving the texture
of the soil. "It is a well-known fact that soils
well stocked with a supply of lime will be more productive
under the same conditions of plant-food content than
soils not so stocked...While soils use very small amounts
of lime as compared with phosphorus and potassium, yet
the presence of a relatively large supply of lime insures
crop production. In the words of Hilgard, 'A lime country
is a rich country'" (1914, Chemical Analysis of
Some Kansas Soils, p. 647-648).
Soil Bacteria
Although the exact relationship did not seem to be
clear, researchers in the early part of the twentieth
century were writing about a correlation between humus
or organic matter, bacteria, and fertility. A series
of studies beginning in the 1890's showed crop yields
in "direct proportion" to the bacterial content
of the fields (1903, Bacteria of the Soil, p. 178).
In this same publication, the authors speculate that
fertility depends to a large extent on bacterial activity
and that by manipulating the bacteria of the soil, one
might avoid the need for artificial fertilization. They
proposed additional experiments to find ways to increase
soil bacteria.
A few years later, Walter King and Charles Doryland
report on their studies of soil bacteria with this same
basic assumption. Assuming that bacterial activity indicated
increased soil fertility, they set about collecting
samples from various soil depths on plots representing
a variety of tillage practices. They admitted tremendous
variability in their data, which was collected over
a period of only three months from March to June 1908.
Nevertheless, they concluded that deep plowing, conveniently
the tillage practice most commonly used at that time,
increased bacteria levels and bacterial activity and
decreased denitrification. They noted that bacterial
activity increased with the temperature of the soil
and decreased when the soil became saturated with moisture.
Different species were predominate at different times
and activity seemed to rise and fall with a regularity
independent of moisture and temperature (1909, The Influence
of Depth of Cultivation Upon Soil Bacteria and Their
Activities, p. 161).
Analysis of the Soil
As farmers began to experience decreasing yields on
exhausted soil, they began to show interest in chemical
analysis of their soil. Inexpensive, reliable soil tests
were not yet available in the early part of the century.
Throckmorton and Call noted that although they could
determine the nutrient needs of a crop and the chemical
analysis of the soil, their current methods did not
tell them what nutrients were available to the crop.
They felt that available nutrients "fluctuate greatly"
depending upon the total nutrients in the soil, the
organic matter content, the weather, cultivation methods
and the current crop. Consequently, a chemical analysis
would only give a farmer a general outline. Probably
the greatest deterrent to using a chemical analysis
was the expense which made it impractical for individual
farmers (1918, Soil Fertility, p. 12).
In 1909, the Extension Station council authorized the
Chemistry Department to collect and analyze typical
soils from across Kansas. This body of work did give
farmers an idea of the basic properties of their soil
and requirements of common crops even if it could not
provide specific answers regarding fertility (1914,
Chemical Analysis of Some Kansas Soils, p. iii).
In 1910, the Chemistry Department cautioned that chemical
analysis of the soil was not a reliable indicator regarding
crop needs. They recommended that the farmer should
test his soil by raising small crop plots that had been
"fractionally fertilized" in order to determine
the optimal rates. The complexities of variable rate
plots involving a significant amount of land and more
than one growing season probably doomed this testing
method for on-farm use.
More practical advice involved a farmer's observational
skills. "Chemical and physical investigation of
soils...must be supplemented or...replaced by observations
upon the natural growth of trees, shrubs, grasses or
weeds upon the soil, and by experiments in the production
of plants or crops upon it. Let organic nature answer
the question, What is this soil good for? Observations
concerning the natural plant growth upon a soil have
always been used by practical men in judging of its
value...This means of gaining an insight into soil values
is one that, while used from time immemorial, is worthy
of more extended study and application (1910, Fertilizers
and Their Use, p. 63).
Commercial Fertilizers
Throughout the Kansas State publications from the first
half of the twentieth century, farmers are cautioned
about reliance on chemical fertilizers. "It should
not be forgotten...that barnyard manure, because of
its content of organic matter in a state of decay, is
superior to chemical fertilizers containing equal amounts
of potassium, phosphorus, and nitrogen compounds"
(1910, Fertilizers and Their Use, p. 67-68).
In 1918, Throckmorton and Call warned that although
commercial fertilizers are more concentrated, they do
not supply organic matter, which is "absolutely
necessary to supply plant food, to preserve good tilth,
and to retain water in the soil." Because commercial
fertilizers do not supply organic matter, "they
can't be expected to replace manure in soil improvement,
but should be used, where they can be used profitably,
in addition to barnyard manure and other forms of organic
matter" (1918, Soil Fertility, p. 30). This caution
continued for more than thirty years while Kansas farmers
were advised to use legumes and manures as nitrogen
sources and pay careful attention to nutrient cycling
on their farms.
In 1956, the Kansas State Agricultural College publication,
"Legumes vs. Commercial Fertilizer" documented
a major change on Kansas farms. The authors reported
on a study of the economics of Kansas cropping systems.
One objective was to understand why farmers were planting
fewer legume acres than were recommended. "Data
indicate considerable advantage to certain legume rotations...Even
though this is more profitable, farmers probably grow
fewer legumes because they need income quickly"
(1956, Legumes vs. Fertilizers, p. 12-13).
Once a farmer began using commercial fertilizers, the
soil would be slow to return to a more natural cycle
of fertility that did not include commercial fertilization.
In 1918, farmers were already asking whether commercial
fertilizers "impoverish the soil." There were
reports that farmers who stopped using commercial fertilizers
experienced reduced crop yields. Throckmorton and Call
explained that these fertilizers "cannot in themselves
be expected to maintain the fertility of the soil. They
should, therefore, be used only when a good rotation
of crops is practiced, and when organic matter is supplied
systematically" (1918, Soil Fertility, p. 31).
Crop Rotations
In the 1910 bulletin, "Fertilizers and Their Use,"
the authors speculate that there is something other
than the chemical analysis of the soil, which affects
plant growth. They expected that rotations of crops
may have an impact on "soil conditions" (1910,
Fertilizers and Their Use, p. 61-62). Without fully
understanding the dynamics of rotations, farmers and
researchers already considered them an essential part
of good soil management.
By 1935, researchers were refining their view of the
use of rotations. "Rotation of crops should not
be loosely recommended without stating specifically
what the rotation should be, or having in mind the wide
differences existing between possible rotations".
Citing studies of soil fertility under various cropping
patterns and soil treatments over a period of twenty
years, Throckmorton and Duly emphasize that not all
rotations can be used interchangeably.
Some rotations are less effective than others at maintaining
soil fertility as well as at providing economic returns.
In some instances, continuous cropping of hay or small
grains for a few years was better for the soil or the
pocketbook than rotations, which included row crops.
Soil quality concerns aside, the prices of individual
crops and their cost of production weigh heavily in
determining the most profitable rotations. As prices
fluctuate, the rotations providing the greatest economic
return also vary.
During the latter half of the 1930's, an analysis of
these continuing soil fertility studies in Manhattan
looked at nitrogen and organic carbon levels. One conclusion
was that within the cropping patterns studied, "the
larger the percentage of the crop cycle occupied by
biennial or perennial legumes or sod crops, the higher
will be this level (of nitrogen and carbon)." The
use of manure, fertilizers, and lime, if they stimulated
crop growth, particularly of a legume, would maintain
higher levels of nitrogen and carbon (1939, Nitrogen
and Organic Carbon of Soils as Influenced by Cropping
Systems and Soil Treatments, p. 24).
Wrong Turns
Besides repeated references to the importance of organic
matter in retaining soil moisture, researchers have
addressed other means of moisture conservation. A very
early bulletin from 1899 examined the possibility that
fertilizers themselves might slow water evaporation
from the soil. Various treatments were tried on outdoor
plots and on small pots within the laboratory over a
number of years. In every case, there was no difference
in treatment (1899, Soil Moisture, p.22).
Perhaps the most intriguing study was sponsored by
the E.I. DuPont de Nomours Powder Company from 1911
to 1913. The dynamite industry had been heavily promoting
the use of their product for improvement of all types
of soils. The study included plots on heavy clay soils
at the Fort Hays and Manhattan experiment stations as
well as on numerous farms across the state. On a field
eighty rods long and eight rods wide, thirty-inch holes
were dug fifteen feet apart in rows sixteen feet apart.
One half stick of dynamite was placed in each hole and
exploded.
Data showed no significant differences in crop yields,
soil moisture, nitrate levels, or bacterial activity
on the dynamited soil. Unfortunately, the physical characteristics
of the soil were considerably diminished. The explosion
forced soil at the center of the charge into the surrounding
pore spaces producing a cavity surrounded by a hard,
compact mass. These "jugs" would fill with
water during rainstorms and hold it until evaporated.
The cost was prohibitive with the dynamite expense
alone at $12.20/acre. Labor was an additional $5.00/acre.
The researchers concluded, "In no instance was
there improvement sufficient to pay the expense of dynamiting"
(1915, The Use of Dynamite in the Improvement of Heavy
Clay Soils, p. 5-6).
Erosion Control
Erosion was recognized as one of the factors resulting
in soil depletion. Throckmorton and Call felt erosion
could be prevented by deep plowing, adding organic matter
and by "working the ground at right angles to the
slope of the land" (1918, Soil Fertility, p. 14).
Although plowing would later be seen as a culprit in
erosion, it may have offered an advantage over shallow
disking by initially creating a rough surface more resistant
to wind.
The merits of organic matter in stabilizing the soil
were universally touted throughout early publications.
However, in 1957, researchers in western Kansas reported
findings indicating that increases in the soil's organic
carbon content did not necessarily mean less susceptibility
to wind erosion. Heavy soils could be more vulnerable
with the addition of well-decomposed organic matter.
Undecomposed crop residues or other organic matter were
beneficial in slowing the effects of the wind (1957,
Nitrogen and Organic Carbon Changes in Cultivated Western
Kansas Soils, p. 25).
Farmers could create another tool to control wind erosion
by alternating strips of crops. Researchers in the 50's
set out to determine the ideal width of these strips
for maximum protection. They considered the quantity
of crop residue and soil roughness that would be produced
during years of low rainfall, high wind, and low crop
yields. Full wind protection during such years required
strips so narrow that they would be impractical to farm.
When combined with other erosion control methods such
as high residue management, the field strips could be
increased in size to an acceptable level and still provide
a high degree of protection (1957, Width of Field Strips
to Control Erosion, p. 13)
A 1962 bulletin on farming systems in western Kansas
notes that contour farming resulted in increased yields
for a wheat, wheat, sorghum, and barley rotation at
Fort Hays. These researchers also experimented with
dikes around very level fields to capture moisture and
found some yield advantage (1962, Investigations of
Cropping Systems, Tillage Methods, and Cultural Practices
for Dryland Farming, p.37).
Western Kansas Cropping Systems
Kansas State research bulletins and publications documenting
the work in western Kansas over the first half of the
1900's reflect a very different type of cropping system
from that used in the eastern parts of the state. Dryland
farming in areas of low rainfall and high winds presents
special challenges for soil health. This flat, arid
region in the western half of the state supports a fragile
wealth that requires careful consideration to maintain
soil resources.
Soil studies in western Kansas date back to the very
earliest years of the twentieth century. A continuous
study of organic carbon and nitrogen in soils at Ft.
Hays Experiment Station lasted for more than thirty
years with follow-up research continuing for at least
another fifteen years. The western Kansas studies covered
a number of topics including the use of fallow periods,
changes in organic carbon and nitrogen, tillage methods,
and crop rotations. In nearly every instance, the principle
concerns were the conservation of soil moisture and
fertility.
Fallow
Fallow is the "practice of keeping land free of
all vegetation throughout one season for the purpose
of storing moisture for a crop the following year (1941,
Summer Fallow in Kansas, p. 5). Where rainfall is too
low to support yearly crop production, fallow can be
an important part of the cropping system.
Using fallow to store soil moisture results in production
stability by decreasing the number of crop failures.
Adherence to the fallowing pattern in high rainfall
years is important since a portion of that moisture
is stored for following dry years (1941, Summer Fallow
in Kansas, p. 23).
In 1962, Ft. Hays researchers reported that milo yields
after fallow were twice the yields of milo crops following
milo. Although this was the greatest percentage increase
for any crop studied, all crops saw increases (1962,
Investigations of Cropping Systems, Tillage Methods,
and Cultural Practices for Dryland Farming). A 1941
publication states that corn, oats, and barley grown
on fallowed ground show a marked increase in quality
even if the yield from one year does not equal two crops.
Fallow in a rotation with forage crops "allows
farms without pasture to reintegrate livestock and supplement
the carrying capacity of those farms with pasture"
(1941, Summer Fallow in Kansas, p. 25-26).
The successful use of fallow is related to soil type
with its greatest value seen on heavier soils that have
an increased moisture storage capacity. Light soils
without a heavy subsoil, shallow soils, and hilly topography
are not likely to provide an economic advantage with
fallowing since moisture cannot be held (1941, Summer
Fallow in Kansas, p. 28-29).
Soil management techniques for fallow rotations must
always be directed toward capturing moisture, preventing
evaporative losses, and timely destruction of weeds.
The average rainfall in western Kansas may be adequate
to produce a crop however the moisture losses from evaporation,
runoff, and weed pressure rob a large portion of the
water before it can be utilized. Throckmorton and Myers
hypothesize that the farmer has little control over
evaporative losses which can be 60-75% of total precipitation.
"Fallow is extravagant in so far as storage of
total precipitation is concerned, but it is essential
as a means of stabilizing production through having
sufficient moisture in the soil at seeding time to justify
the seeding of a crop" (1941, Summer Fallow in
Kansas, p. 13).
Tillage is a key to the successful management of runoff
and weed growth. "A good summer fallow is one in
which the soil is free of all growing plants throughout
the fallow period and has a rough open surface which
will permit a ready and rapid penetration of moisture."
If possible the stubble of the preceding crop should
be left standing during the winter and spring to capture
snow and prevent wind erosion. Thereafter, cultivation
should be used when weeds are still small and the soil
will form clods to create a rough surface. To further
protect the soil from wind erosion, fallow strips can
be alternated with crop strips following field contours.
The fallow that is poorly managed is doubly exposed
to the wind. Proper management is an effective means
of checking erosion (1941, Summer Fallow in Kansas,
p. 14-20).
In 1962, Luebs adds that shallow cultivation using
a one-way disk plow or a subsurface tillage tool is
just as effective as a plow or a lister for destroying
weeds. This type of tillage leaves plant residues on
the surface of the soil to slow the wind action (1962,
Investigations of Cropping Systems, Tillage Methods,
and Cultural Practices for Dryland Farming, p. 36).
Organic matter content of western Kansas soils
General soil management techniques would indicate that
increasing the organic matter content of the soil would
be one tool to build its water holding capacity. Long
term studies of organic carbon and nitrogen levels in
soils at Colby, Hays, and Garden City provide an interesting
look at organic carbon levels.
All cropping systems examined in the studies were resulting
in decreases in both soil carbon and nitrogen levels.
The cropping systems were generally depending upon native
fertility of the soil or some applications of manure
for crop production. Continuous small grain production
or small grains in rotation with a fallow period showed
the least destruction of soil organic matter levels.
The practice of fallowing in itself decreased organic
matter levels since nothing was allowed to grow on the
soil but when fallow was used in a rotation with small
grain crops, the losses were decreased (1957, Nitrogen
and Organic Carbon Changes in Cultivated Western Kansas
Soils).
The use of green manure crops to build organic matter
might be considered in a higher rainfall area. However,
as early as 1918, researchers warned western Kansas
farmers that green manure crops would use too much moisture
prior to the main crop. They recommended finding some
other source of organic matter (1918, Soil Fertility,
p. 23).
Sampling for the long-term studies began in 1916 and
in each successive report, researchers found that applications
of animal manure and/or straw slowed the loss of organic
carbon and nitrogen or provided a small increase. The
relationship with regard to crop yields was less positive.
In 1943, researchers reported that manure applications
increased yields only under "certain conditions"
and added that "perhaps (manure's) advantage will
become more evident in the future (1943, Nitrogen and
Carbon Changes in Soils, p. 34). In 1957 manure and
straw applications showed no benefit to yield data.
Citing the maintenance of nitrogen and organic matter
content, researchers concluded that "these results
indicate, even at the present time, that all manure
should be conserved and applied to the land (1957, Nitrogen
and Organic Carbon Changes in Cultivated Western Kansas
Soils, p. 23).
In 1962, researchers stated the manure was of "negligible"
value for wheat and sorghum in a fallow-wheat-sorghum
rotation (1962, Investigations of Cropping systems,
Tillage Methods, and Cultural Practices for Dryland
Farming, p. 37). In 1965, after more than forty years
of soil studies at the Ft. Hays Experiment Field, the
researchers acknowledge that green manures and animal
manure applications lower nitrogen and organic carbon
losses. But they maintained that their use to maintain
soil productivity "in this area is not practical"
citing the need for 25-30 tons of manure per acre every
three years to maintain nitrogen and carbon levels (1965,
Effects of Cropping and Management of Nitrogen and Organic
Carbon Contents of a Western Kansas Soil, p. 19).
The data regarding crop yields and carbon levels in
these studies did not vary significantly over the course
of forty years. However the conclusions regarding "practicality"
are considerably different. It may be that as farming
practices changed and manure was less accessible on
the average farm, its use was, indeed, less practical.
As livestock concentration has increased in some parts
of western Kansas at the end of the twentieth century,
we are once again revisiting the practicality of manure
applied to cropland. Although the economics may be driven
by a need to dispose of excess manure, wise use indicates
the "practicality" of using those manures
to build fertility and organic matter levels.
Fertility of Western Kansas Soils
"From a practical standpoint, the question of
the use of nitrogen fertilizers in western Kansas presents
a number of important problems." Researchers in
1943 could see that frequent crop failures and low yields
were due to limiting factors other than fertility -
principally moisture. They also felt that the use of
summer fallow "will reduce the need (for fertilizers)
due to the accumulation of nitrate nitrogen" (1943,
Nitrogen and Carbon Changes in Soils, p. 33). For years
they examined nitrogen changes in the soils and considered
the best course for maintaining fertility at a level
that permitted crop production with an economic return.
The first sixteen years of the long term soil studies
at Hays, Colby, and Garden City showed nitrogen losses
from 1916-1938 that were nearly equal to the nitrogen
removed by the crops. The losses immediately following
sod breaking were greater than the losses later in the
study. For a time, there was hope that this trend indicated
a possible equilibrium for nitrogen levels (1943, Nitrogen
and Carbon Changes in Soils, p. 4)
Nitrogen lost through crop removal was being somewhat
offset by the deposition of nitrogen in rain and snow
during the fallow period. However, researchers estimated
this amount to be only three to eight pounds per acre
per year with an average deposition of 3.44 pounds per
acre each year. They also speculated that there might
be some fixation of nitrogen by free-living bacteria
(Azotobacter and Clostridium) although they had not
been able to verify this was true in any field experiments
(1957, Nitrogen and Organic Carbon Changes in Cultivated
Western Kansas Soils, p. 24).
Crop yields in these early studies fluctuated so much
depending on rainfall patterns, no trend in decreasing
yields due to fertility could be tracked. (1943, Nitrogen
and Carbon Changes in Soils, p. 30). It is most likely
that farmers were still mining the native fertility
of the soil but at a much slower rate than the farmers
in the eastern half of the state due to the difference
in rainfall.
Considering the fragility of western Kansas cropping
systems, farmers in that area need to be able to adapt
their cropping patterns to fit the current conditions.
"The successful dryland farmer in this area must,
as far as possible, be flexible in choosing cropping
sequences, tillage methods, and cultural practices".
He or she must consider the weather, soil conditions,
preceding crops, residue, weed populations, soil moisture,
tilth, and the removal of nutrients (1962, Investigations
of Cropping Systems, Tillage Methods, and Cultural Practices
for Dryland Farming, p. 37).
Looking to the future of Kansas soils
Although healthy soil is the basis for the rich diversity
of agriculture in Kansas, a host of barriers, both economic
and social, prevent us from protecting and building
soil quality. Short term leases of rented farm ground
discourage the use of practices that only see an economic
return after multiple years. Inexpensive commercial
fertilizers have precluded the need to monitor nutrient
cycling on the farm.
New interest in protecting water quality, conserving
water use, managing excess livestock wastes, and developing
farming systems that reduce the use of commercial fertilizers
and pesticides may refocus attention on some of the
same questions that were addressed during the first
half of the twentieth century. Farmers may gain understanding
from the early research of Kansas State University and
then begin to ask the questions that will lead us into
the twenty-first century with renewed interest in our
soil.
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