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I. Origin of Crop Rotations

I. Origin of Crop Rotations

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CROP ROTATIONS FOR THE 2 1st CENTURY



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likely use of this crop rotation was in a legume-cereal system. In Italy during the

first century B . c . , Varro also noted the importance of a green manure crop,

especially legumes, in cropping systems prevalent at that time.

Despite the beneficial effects of crop rotation, the practice fell out of favor with

the demise of Roman power throughout Europe (White, 1970b). Less use of crop

rotation and a return to the old crop and fallow system appeared to occur with the

return to a more rural civilization as the more urban civilization prevalent in the

Roman Empire disappeared.

Throughout the Middle Ages, little mention is made of crop rotation and as

noted earlier, the prevalent practice was probably the crop-fallow system. One

exception mentioned for this period was the practice of alternating 2 years of

wheat and 5 years of grass in a system called ley farming (crop rotation). This

sequence was used by the Monks of Couper around 1400 in Britain (Franklin,

1953). Crop rotation was probably used to some extent during this period, but it

appears that a crop-fallow system, with the use of manure, was the general

system in use.

Crop rotations, as we now know them, are often traced back to the Norfolk

rotation. This was popular in England about 1730 (Martin et al., 1976). The

Norfolk rotation, which was widely used at the time, consisted of turnip, barley,

clover, and wheat in a 4-year sequence. The Norfolk and many other similar

rotation systems were in use throughout the 18th century, but little was actually

known about the specific benefits of rotating crops. The prevailing thought was

that each of the crops in the rotation obtained their nutrients from different zones

or parts of the soil. This perception was used to explain why a sequence of

different crops yielded better than a single crop grown year after year.

Between 1730 and 1840 the practice of crop rotation and the use of artificial

manure (lime and other soil minerals) to supplement animal manure had become

almost universal in England (Parker, 1915). One early English agricultural writer, Arthur Young, was not necessarily a proponent of this system. Young was a

great apostle of mixed farming. He lauded the value of legumes, the use of crop

rotation, and the feeding of livestock on the farm and the return of the manure to

the land. Young insisted grass land and grazing were of primary importance and

management of arable land of secondary importance to English agriculture.

However, he did emphasize the importance of crop rotation and animal husbandry to agriculture at the time (Parker, 1915).

As would be expected because of the heavy influence of English and Scottish

settlers, most early agriculture in the United States was based on English customs. Several letters between Thomas Jefferson and George Washington (Bureau

of Agricultural Economics, 1937) support this statement and indicate that crop

rotation was also the prevalent practice in the United States. Jefferson wrote in a

letter addressed to President Washington in 1794 that he was going to have to use

a milder course of cropping because of the ravages brought about by overseers



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D. L. KARLEN E T A .



during his absence. His rotation was first year, wheat; second, corn (Zea mays

L.), potatoes (Solanum tuberosum L.), or pea; third, rye (Secale cereale L.) or

wheat, according to the circumstances; fourth and fifth, clover or buckwheat

(Fagopyrum esculentum Moench); and sixth, something he described as folding

or buckwheat if it had not been used in the fourth or fifth years. Another letter,

dated 1798, indicated he was using a triennial rotation of 1 year of wheat and 2

years of clover in his stronger fields or 1 year of wheat and 2 years of pea in the

weaker fields followed by a crop of Indian corn and potatoes between every other

rotation. Jefferson commented in both cases that he felt these types of cropping

systems, with the addition of some manure, would help his fields recover their

pristine fertility at Monticello. In later years, after retiring from the presidency,

Jefferson returned to Monticello and noted in a letter to C. W. Peale in 1811 that

his rotations were mainly corn, wheat, and clover; corn, wheat, clover, and

clover; or wheat, corn, wheat, clover, and clover. It was apparent that he knew

well the benefit of rotation with legumes by the prevalence of clover in each of

these systems.

In some of his letters and papers, George Washington described a good crop

rotation plan that he found in use on Long Island in 1790. It consisted of corn

with manure, oats (Avena sativa L.) or flax (Linum usitatissimurn L.), wheat with

4 to 6 pounds of clover and 1 quart of timothy (Phleum pratense L.), and

meadow or pasture. From 1800 to 1810 this same rotation with some slight

modifications came into quite general use in Pennsylvania. However, in Virginia, a rotation similar to that of Jefferson’s was used by many farmers (Parker,

1915).

Jefferson, Washington, and many other progressive farmers of the time used

rotations and manure extensively in an attempt to regain productivity levels

similar to those when the virgin soils of the United States were first broken out.

In other parts of the world, it was apparent crop rotations and other systems

similar to the Norfolk rotation were in extensive use by farmers during the 19th

century. Despite their extensive use of rotations, agriculturists of the time, such

as Baron Justis von Liebig (1 859), believed that although crop rotation improved

the physical and chemical condition of the soil, all plants would eventually

exhaust the soil. Liebig felt that unless soils were heavily manured, all fields

would eventually lose their fertility, regardless of crop rotation.

Hall (1905) presents an excellent summary of the prevailing thoughts and

experiments concerning crop growth and production during the 19th century. It

was during this time period that researchers discovered legumes had the ability to

assimilate and utilize nitrogen from the atmosphere, which enlightened researchers regarding the benefit of growing crops in rotation with legumes. As

described by Hall (1905), this discovery provided an explanation as to the benefit

of existing crop rotation studies and led to new investigations on crop rotations

during the 19th century at Rothamsted, England (the world’s first agricultural



CROP ROTATIONS FOR THE 2lst CENTURY



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research station). These studies further identified that some of the nitrogen fixed

by the legumes in a cropping system becomes available for succeeding crops and

clearly identified at least part of the beneficial effects of crop rotations.



11. 20th CENTURY CROP ROTATIONS

A. PRE-WORLD WAR 11

The discovery in the latter part of the 19th century that legumes could fix

nitrogen from the atmosphere was a major reason rotations remained popular into

the early part of the 20th century. Nitrogen was the major limiting nutrient for

most crops and it could only be supplied by the addition of manure or by

incorporating a legume of some type in the cropping system. Use of crop rotation

during this period, similar to patterns established throughout history, was greatly

dependent on the amount of new or virgin land available for crop production. If

cheap and plentiful amounts of fertile land were available, crop rotations were

not extensively used. Only as land became more expensive and less plentiful

were crop rotations utilized more extensively.

Johnson (1927) presented examples of rotation experiments conducted in several different areas of the United States during the early part of the 20th century.

In Georgia, the suggested rotation was corn, cowpea (Vigna unguiculata L.),

oat, and cotton. Cowpea was sown during the last cultivation. The corn was

harvested for grain and the cowpea was worked into the soil. Oat was sown in

late fall and harvested in late May or early June. Cowpea was sown again as a

green manure crop to be incorporated the next spring just before planting cotton

(Gossypiurn hirsuturn L.). This crop sequence increased cotton yields as much as

100% after the first series of the rotation and even greater increases in productivity were maintained in successive rotations.

Rotation experiments at the University of Missouri that began in 1888 included a 6-year corn, oat, wheat, clover, timothy, and timothy rotation and a

3-year corn, wheat, and clover rotation. According to Johnson (1927), after 30

years, yields of corn were increased 60.4%, oat 3%, and wheat 32% in the 6-year

rotation and 30.8% for corn and 40.8% for wheat in the 3-year rotation over the

yields of the corresponding continuously cropped areas. Manure applications

averaged 6.8 tons annually in both rotation and continuous cropping systems.

Results from an Ohio experiment were similar (Johnson, 1927). The main

difference between the Ohio and Missouri experiments was the use of fertilizers

instead of manure. Yields of corn, oat, and wheat in rotation were increased

29.9, 30.8, and 42.5%, respectively, above yields of those crops in continuous

culture. In Delaware, corn grain yields increased 156.9% in a rotation of corn



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D. L. KARLEN ET AL.



(including a cover crop of rye and vetch), soybean [(Clycine m u (L.) Merr.)],

wheat, clover, and timothy as compared to continuous corn when no fertilizer or

manure was used. With nitrogen, phosphorus, and potassium applications corn

grain yields still increased 24.4% in rotation as compared to the continuous corn

system (Johnson, 1927).

Cover crops were widely recommended for many cropping systems in the

early 20th century (Johnson, 1927). Among these systems was one including two

crops of kale (Brassica oleracea var. acephala DC.), three of cabbage (Brassica

oleracea var. capitata L.), three of potatoes, three of sweet potatoes [(Zpornoea

batatas (L.) Lam.)], and one of German millet [(Setariaifulica (L.) P. Beauv.)].

These 12 crops were grown in rotation during the 9-year period from 1912 to

1921 both with and without cover crops at the Virginia Truck Experiment Station. Similar to the experiments just described, both rotations received the same

amount of fertilizer, nitrogen, phosphorus, and potassium. Rotation again increased yields, but yields were increased to an even greater extent with the use of

cover crops. Yield increases ranged from 12.5% for kale to 62.5% for millet with

cover crops. In this experiment, rotation was considered a major factor contributing to disease control in truck crops and probably contributed greatly to the yield

increases. Other popular rotations for truck farmers in Virginia at this time

included a 3-year rotation of potatoes, corn, and rye grown during both the first

and second year, and sweet potatoes and rye grown during the third year. In

Norfolk County, Virginia, early potatoes were grown as a spring crop. This was

followed by a cover crop of native grass, which was cut for hay, or legumes such

as soybean or cowpea, which were incorporated in the fall. Cabbage was then

planted in November and harvested the following April or May just before

planting a corn crop. Sometimes, soybean was planted directly in the row with

the corn and rye was sown between the rows at last cultivation as intercrops.

When the corn was harvested, the cycle, starting with early potatoes, was repeated. This Norfolk County, Virginia, rotation consisted of two main crops

(potatoes and cabbage), two catch crops, the hay, and corn crop (Johnson, 1927).

With small modifications, this was similar to most of the truck crop rotations

used throughout the eastern United States.

In the same symposium, Lyon (1927) described the effects of legumes and

grasses in different crop rotations. Most of the systems he described were similar

to a corn, oat, wheat, and hay rotation, where the hay was usually either a

legume or a grass such as timothy. He concluded that with few exceptions,

experiments conducted at eight experiment stations in the humid regions of the

United States generally showed legumes to be superior to grasses for increasing

yields of the following crops. In the drier parts of the country, however, grasses

were generally superior to legumes because they usually did not deplete soil

moisture as extensively as legumes.

Crop rotation was not a widely accepted practice in the United States corn belt

during the early 20th century. The soils were extremely fertile and after the virgin



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