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Sustainable
Agriculture
Focus on issues facing farmers and producers
The
issues that are important to farmers across the country include
stewardship, profitability, sustainability and the health of
their community. And those are the topics to be covered in
Kansas in an upcoming agriculture roundup.
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.
The following documents have been identified as those
historical publications which are relevant to sustainable
agriculture in the Soil Management category.
An historical
summary by Lisa French highlights the significant research
and
recommendations.
Bidwell, O. W. July 1956. Major Soils of Kansas. Circular
336. Agricultural Experiment Station. K-State College of
Agriculture and Applied Science.
Bray, James O. and John A. Schnittker. November 1956. Legumes
or Commercial Fertilizer? Bulletin 384. Agricultural Experiment
Station, Kansas State College of Agriculture and Applied
Science.
Call, L.E. and Throckmorton, R.I. December 1915. The
Use of Dynamite in the Improvement of Heavy Clay Soils. Bulletin
209 Agricultural Experiment Station, Kansas State
Agricultural College.
Call, L.E. and Throckmorton, R.I. August 1918. Soil
Fertility. Bulletin 220 Agricultural Experiment Station,
Kansas State Agricultural College.
Chepil, W.S. 1957. Width of Field Strips to Control Wind
Erosion. Technical Bulletin 92. Agricultural Experiment Station,
Kansas State College of Agriculture and Applied Science.
Hobbs, J.A. and Brown, P.L. 1957. Nitrogen and Organic Carbon
Changes in Cultivated Western Kansas Soils. Technical Bulletin
89. Agricultural Experiment Station, Kansas State College of
Agriculture and Applied Science.
Hobbs, J.A. and Brown, P.L. 1965. Effects of Cropping and
Management of Nitrogen and Organic Carbon Contents of a Western
Kansas Soil. Technical Bulletin 144. Agricultural Experiment
Station, Kansas State College of Agriculture and Applied
Science.
King, W.E. and Doryland, C.J.T. August 1909. The
Influence of Depth of Cultivation upon Soil Bacteria and their
Activities. Bulletin161 Experiment Station, Kansas State
Agricultural College.
Luebs, R.E. 1962. Investigations of Cropping Systems, Tillage
Methods, and Cultural Practices for Dryland Farming. Bulletin
449. Fort Hays Branch of the Kansas Agricultural Experiment
Station, Kansas State College of Agriculture and Applied
Science.
Mayo, N.S. and Kinsley, A.T. May 1903. Bacteria
of the Soil. Bulletin 117 Experiment Station, Kansas State
Agricultural College.
Metzger, W.H. May 1939. Nitrogen and Organic Carbon of Soils
as Influenced by Cropping Systems and Soil Treatments. Technical
Bulletin 45. Agricultural Experiment Station, Kansas State
College of Agriculture and Applied Science.
Myers, M.E., Hallsted, A.L.; Kuska, J.B.; and Haas, H.J.
1943. Nitrogen and Carbon Changes in Soils. Technical Bulletin
56. Agricultural Experiment Station, Kansas State College of
Agriculture and Applied Science.
Swanson, C.O. June 1914. Chemical
Analyses of some Kansas Soils. Bulletin 199 Agricultural
Experiment Station, Kansas State Agricultural College.
Throckmorton, R.I. and Meyers, H.E. March 1941. Summer
Fallow in Kansas. Bulletin 293 Agricultural Experiment
Station, Kansas State College of Agriculture and Applied
Science.
Willard, J.T. and Clothier, R.W. June 1899. Soil
Moisture. Bulletin 89 Experiment Station, Kansas State
Agricultural College.
Willard, J.T., Swanson, C.O., and Wiley, R.C. September 1910.
Fertilizers
and their Use. Bulletin169 Experiment Station, Kansas State
Agricultural College
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