**1.2 Advent of agricultural education and research**

The Morrill Act of 1862 and again 1892 established the American Land-Grant colleges in each state and charged them with the responsibility of teaching the agricultural and mechanical disciplines, along with other responsibilities necessary to an advanced education. The Hatch Act of 1887 then established the Agriculture Experiment Station system which, in most states, is administered by the Land-Grant Universities and was to provide further enhancement of agricultural teaching through experimentation. In 1914 the Smith-Lever Act established the State Cooperative Extension Service which disseminates information to the public of advances in agriculture production discovered by the state agricultural experiment stations. All three of these legislative acts came about because of a need to better understand sound farm management practices, including crop rotations, to improve the nation's farm economy.

The concept of agriculture research stations was not an American idea. The Rothamsted Experiment Station in the United Kingdom is said to be the world's oldest, being established in 1843, while Möcken station in Germany, established in 1850, is said to be the world's oldest state supported agricultural research station. Agricultural research stations can now be found in most all developed countries and even many less developed nations. Research on crop rotations has been and continues to be conducted at virtually all of these stations,

Rotation C (g kg-1) N (g kg-1) C-N ratio

Continuous corn 19.2a 1.55a 12.36a Corn-oats 23.0b 1.84b 12.46a Corn-oats-hay 26.5c 2.12c 12.48a

Table 2. Soil carbon C, nitrogen N, and C-N ration from a crop rotation experiment on the

Means of samples taken in 1904, 1911, 1913, 1923, 1933, 1943, 1953, 1961, 1973, 1974, 1980, 1986, and 1992. (Aref and Wander, 1998). Values within a column followed different letters

Corn and wheat yields at Sanborn Field at the University of Missouri have been consistently higher when grown in rotation with each other along with red clover (*Trifolium pratense* L.) inter-seeded into the wheat in late winter for forage the following year (Miles, 1999). Plots of both corn and wheat have been grown continuously since the site's establishment in 1888, some receiving animal manure, some commercial fertilizer, and some no fertility treatment. All have had reduced grain yields compared to those grown in rotation, even with the

Thirty years after Sanborn Field's establishment, its focus began to shift to the study of cropping systems as related to soil erosion and the resulting loss of productivity. An experiment conducted in 1917 by F.L. Duley and M.F. Miller on the campus of the University of Missouri used seven test plots to measure soil erosion resulting from rainfall (Duley and Miller, 1923). This research led to creation of the Soil Conservation Service of the USDA, which in now a component of NRCS-USDA. It led to the establishment of experiment stations throughout the United States dedicated to the study of crop rotations on soil erosion and developing cropping systems to minimize erosion's impact (Weaver and Noll, 1935). Experiments at these stations in Iowa, Missouri, Ohio, Oklahoma, and Texas all showed plots planted to a continuous cropping system had higher surface soil losses and losses of rainfall than plots planted to a forage or in a three or four year rotation (Uhland,

Crop rotation schemes are, by and large, regional in nature and a specific rotation in one environment may not be applicable in another. Continuous cropping schemes or monocultures for the most part, have fallen out of favor in many farming regions. Roth (1996) published mean corn yields from a 20 year crop rotation experiment in Pennsylvania that included rotation with both soybean and alfalfa showing higher yields with all rotation schemes than continuous corn (Table 3). The extensive use of commercial fertilizers and pesticides has helped mask most of the beneficial effects of crop rotation. But Karlen et al. (1994) has stated" no amount of chemical fertilizer or pesticide can be fully compensated for crop rotation effects". However, economics continues to be the large determining factor into

Morrow Plots of the University of Illinois.

are significantly different P0.05.

added manure and/or fertilizer.

**2. Crop rotations vs. continuous cropping** 

1948).

how a field is managed.

with specialization towards the environment and crop species indigenous to their location. Some of these studies have been in existence since the late 19th century (Rothamsted, 2011).

Some of the more famous experiments in the United States that continue to be performed at some of the Land-Grant Universities, and are now designated on the National Register of Historic Places, include The Old Rotation experiment on the Auburn University campus in Alabama, The Morrow Plots on the campus of the University of Illinois, and Sanborn Field at the University of Missouri. Mitchell et al., (2008) published that the Old Rotation experiment in Alabama has shown over the long-term, seeding winter legumes were as effective as fertilizer N in producing high cotton lint yields and increasing soil organic C levels. Rotation schemes with corn or with corn-winter wheat- and soybean (*Glycine max* L. Merr.) produced no yield advantage beyond that associated with soil organic C (Table 1). However, winter legumes and crop rotations contributed to increased soil organic matter and did result in higher lint yields.


†Values followed by the same letter are not significantly different at P<0.05

‡Recent data show the effect of increasing soil organic matter on cotton productivity.

Table 1. Long-term effects of crop rotations, winter legumes and nitrogen fertilizer on cotton lint yields at the "Old Rotation Experiment" of Auburn University in Alabama. (Mitchell, 2004).

Data from the Morrow Plots in Illinois have shown that yields from continuous corn have always been much less than corn yields from a of corn-oats (*Avena sativa* L.) rotation or a or corn-oats-and hay (clover (*Trifolium* spp.) or alfalfa (*Medicago sativa* L.)) rotation (Aref and Wander, 1998). After the introduction of hybrid corn varieties in 1937, the first plots to show an increase in corn yields due to these varieties were the corn-oats-hay rotation. Yield increases due to hybrids were not noticed in the corn-oat plots until the late 1940's and in the continuous corn plots until the early 1950's. These lower corn yields of the continuous corn and the slower response to corn hybridization in the corn-oat rotation appear to coincide with long-term average levels of soil organic matter and nitrogen observed in the various plots (Table 2).

28 Agricultural Science

with specialization towards the environment and crop species indigenous to their location. Some of these studies have been in existence since the late 19th century (Rothamsted, 2011). Some of the more famous experiments in the United States that continue to be performed at some of the Land-Grant Universities, and are now designated on the National Register of Historic Places, include The Old Rotation experiment on the Auburn University campus in Alabama, The Morrow Plots on the campus of the University of Illinois, and Sanborn Field at the University of Missouri. Mitchell et al., (2008) published that the Old Rotation experiment in Alabama has shown over the long-term, seeding winter legumes were as effective as fertilizer N in producing high cotton lint yields and increasing soil organic C levels. Rotation schemes with corn or with corn-winter wheat- and soybean (*Glycine max* L. Merr.) produced no yield advantage beyond that associated with soil organic C (Table 1). However, winter legumes and crop rotations contributed to increased soil organic matter and did result in higher lint yields.

Cotton Lint Yield (kg ha-1)

1986- 1995†

corn-small grain-soybean 850ab 1109a 2.3a

Table 1. Long-term effects of crop rotations, winter legumes and nitrogen fertilizer on cotton lint yields at the "Old Rotation Experiment" of Auburn University in Alabama. (Mitchell, 2004).

Data from the Morrow Plots in Illinois have shown that yields from continuous corn have always been much less than corn yields from a of corn-oats (*Avena sativa* L.) rotation or a or corn-oats-and hay (clover (*Trifolium* spp.) or alfalfa (*Medicago sativa* L.)) rotation (Aref and Wander, 1998). After the introduction of hybrid corn varieties in 1937, the first plots to show an increase in corn yields due to these varieties were the corn-oats-hay rotation. Yield increases due to hybrids were not noticed in the corn-oat plots until the late 1940's and in the continuous corn plots until the early 1950's. These lower corn yields of the continuous corn and the slower response to corn hybridization in the corn-oat rotation appear to coincide with long-term average levels of soil organic matter and nitrogen observed in the

0 N/no winter

legumes + 134 kg N

†Values followed by the same letter are not significantly different at P<0.05

‡Recent data show the effect of increasing soil organic matter on cotton productivity.

1996-

legumes 392d 403b 0.8e

winter legumes 952ab 1131a 1.8c 134 kg N ha-1 792c 1154a 1.6d

winter legumes 870ab 1120a 1.8c

ha-1 970a 1276a 2.1b

2002† Soil OM %‡

Continous Cotton

Cotton-Corn Rotation

3-Year Rotation (common-

winter legumes

various plots (Table 2).


Table 2. Soil carbon C, nitrogen N, and C-N ration from a crop rotation experiment on the Morrow Plots of the University of Illinois.

Means of samples taken in 1904, 1911, 1913, 1923, 1933, 1943, 1953, 1961, 1973, 1974, 1980, 1986, and 1992. (Aref and Wander, 1998). Values within a column followed different letters are significantly different P0.05.

Corn and wheat yields at Sanborn Field at the University of Missouri have been consistently higher when grown in rotation with each other along with red clover (*Trifolium pratense* L.) inter-seeded into the wheat in late winter for forage the following year (Miles, 1999). Plots of both corn and wheat have been grown continuously since the site's establishment in 1888, some receiving animal manure, some commercial fertilizer, and some no fertility treatment. All have had reduced grain yields compared to those grown in rotation, even with the added manure and/or fertilizer.

Thirty years after Sanborn Field's establishment, its focus began to shift to the study of cropping systems as related to soil erosion and the resulting loss of productivity. An experiment conducted in 1917 by F.L. Duley and M.F. Miller on the campus of the University of Missouri used seven test plots to measure soil erosion resulting from rainfall (Duley and Miller, 1923). This research led to creation of the Soil Conservation Service of the USDA, which in now a component of NRCS-USDA. It led to the establishment of experiment stations throughout the United States dedicated to the study of crop rotations on soil erosion and developing cropping systems to minimize erosion's impact (Weaver and Noll, 1935). Experiments at these stations in Iowa, Missouri, Ohio, Oklahoma, and Texas all showed plots planted to a continuous cropping system had higher surface soil losses and losses of rainfall than plots planted to a forage or in a three or four year rotation (Uhland, 1948).
