STRIP CROPPING AND CONTOURING
Department of Agronomy
The risk of erosion is the most commonly
encountered hazard in the use of Kentucky's farmlands for agricultural
production. On a statewide basis, about 75 percent (11.4 million acres)
of the 15 million acres of land suitable for producing row crops, hay and
meadow crops, or permanent pasture crops has some degree of erosion risk.
Although the degree of erosion risk
varies within the state, most Kentucky farmers have at least one field
where there is need for cropping systems and cultural practices to help
reduce erosion. To determine what production system is best, each sloping
field should be evaluated for soil characteristics and erosion loss potential.
On this basis, the need for specific erosion control practices can be identified
which will enable the field to be used to its maximum agricultural potential.
Two crop production practices that can be used to reduce erosion are strip
cropping and contouring.
Producing crops in strips running across
the slope can greatly reduce the risk of erosion by cutting surface water
runoff approximately in half. Using strips effectively shortens the slope
length, thereby slowing runoff of surface water from sloping fields. Adding
sod waterways in natural channels on hillsides and using no-till techniques
to plant crops into the strips should almost eliminate the erosion problem.
This approach to erosion control has
particular advantage since: 1 ) no additional production costs are involved,
and 2) it enables a more intensive use of sloping fields.
Evaluating Fields for Strip Cropping
Each field should be evaluated to determine
1)Which crops can suitably be
grown on the field's soils--This largely depends on the depth of the rooting
zone. If there are 36 to 42 inches through which roots can grow, any crop
climatically adapted to an area should grow well. If presence of such features
as a fragipan, clay layer, bedrock or high water table occurs at depths
shallower than 36 to 42 inches, then crop selection and cropping systems
should be developed to minimize the potential effect of these features
on crop production.
2)The most effective surface
water management system for the field-gully erosion can be prevented by
establishing sod-based waterways in the naturally-occurring major drainage
channels running down slopes of the field. Using practices such as surface
residue management, minimum tillage or no-till, winter cover crops, and
crop rotations, in addition to establishing strips, will reduce the risk
of rill and sheet erosion.
3)The specifications for strips
to be used on the field--The USDA-Soil Conservation Service (SCS) can provide
technical help in laying out strips to keep them of constant width, yet
somewhat along the field contour. Strip width will largely be determined
by degree of slope and cropping system to be followed, but is not likely
to be narrower than 25 feet nor wider than 75 feet. In all cases, width
should be some multiple of planting equipment to be used. Enough space
(40 to 50 feet) must be left on each end of each strip to enable machinery
to turn. This border on each end of the field should be in a continuous
perennial sod. Production from these areas, as well as from sod waterways,
can be obtained by cutting and baling hay.
Some fields, notably in the Pennyroyal
area of Kentucky, may have such variable slope that it is not possible
to follow slope contours. In such cases, straight parallel strips of constant
width will still provide a good measure of erosion control, particularly
if no-till planting is used and crops are rotated among the strips.
Establishing Cropping Systems in Strips
Each strip should be viewed as a small,
individual field, since many management decisions will be made on each
strip or on groups of strips. Which crop rotation to use is probably the
most basic of these decisions, since strip cropping will most likely involve
growing at least two crops in some form of rotation among the strips. Although
there are numerous possibilities for cropping systems, the following ones
are the most common:
• tobacco - sod (legume and/or grass)
• corn - soybean (either full-season
or double-crop soybeans)
• corn - red clover
• corn - alfalfa
of tobacco with a sod-forming crop is a desirable production practice.
A system of two years continuous tobacco followed by two years of a perennial
sod crop provides fewer soil-borne disease problems and better maintenance
of soil "tilth," to which tobacco responds. Additionally, less nitrogen
is required for tobacco following plow-down of a good sod. Red clover,
tall fescue, orchard grass or timothy are all perennial forage species
that, either seeded alone or as a red clover-grass mixture, provide excellent
hay production during the sod part of the rotation. They also provide an
excellent sod to plow under for tobacco production. This system works extremely
well in fields laid off in strips rotated between tobacco and hay every
two years. In this system, one full cycle of the rotation in each strip
• Year 1 - tobacco (followed by winter
• Year 2 - tobacco (followed by clover-grass
• Year 3 - clover-grass hay
• Year 4 - clover-grass hay
Then, for year 5, rotate back to tobacco. By initially planting tobacco
in alternate strips, the sod crop also exists in alternate strips.
has become a fairly common rotation in some parts of Kentucky, particularly
where fields are Johsongrass-free or where Johsongrass can be controlled.
It is often combined with the "double-cropping" of wheat or barley with
soybeans to provide for three acres of grain production on each acre of
land every two years.
This rotation used in "strips" provides
a unique advantage to producers since its inherent conservation aspects
allow much land with moderate to severe erosion hazard to be used intensively
for continuous corn and soybean production. This particularly is true when
used with no-till planting or other surface residue management practices.
Following corn harvest, wheat or barley
is seeded. Following small grain harvest, soybeans are immediately no-till
planted into the small grain stubble. This rotation is completed by growing
corn following the soybean crop. It allows intensive use of land by double-cropping.
When crops are rotated: 1 ) production is usually improved as compared
to continuous culture of either, 2) there is better broad-spectrum weed
control (chemical treatments for Johsongrass control are generally more
practical with soybeans than with corn), and 3) there is better control
of soil-borne insects and diseases. (This rotation can be helpful in controlling
the soybean cyst nematode.)
This system also works well for producers
with silage-requiring livestock operations. In this case, small grain following
the soybeans could be chopped for silage near mid-May, making it possible
to plant full-season double-crop soybeans. The corn strips would be chopped
for silage or harvested for grain in whatever proportion necessary for
a specific feeding operation. Following harvest of corn silage, fields
should be seeded to a winter cover crop.
A modification of this system to allow
full-season production of soybeans would consist of corn and soybeans being
grown on alternate parallel strips. However, small grain would be seeded
only on strips from which soybeans were harvested. Rye is probably the
best small grain species for this system, since the purpose of following
soybeans with small grain is to provide additional overwinter cover to
the sparse soybean residue and to provide a mulch for no-till planting
of corn the following spring. On the strips from which corn is harvested,
no cover crop would be planted since there is sufficient residue left behind
the combine to adequately protect the soil over winter. Corn strips would
be chisel-plowed or disked the following spring and used for planting full-season
soybeans. The advantage of this modified strip system would be the higher
yields normally obtained from full-season soybeans, and the lesser expense
and time in seeding a winter cover crop. Additionally, each strip would
be deep-plowed in alternate years, loosening any traffic-caused soil compaction
and incorporating surface-applied lime and fertilizer deeper into the rooting
Grain sorghum can be substituted for
soybeans in this alternate strip rotation and produced either as a full-season
crop or double-cropped.
The sequence of strips for the corn-soybean
rotation would be:
• Year 1--no-till corn: winter cover crop or winter fallow with residues
• Year 2--soybeans: winter cover crop
• Year 1--soybeans: winter cover crop
• Year 2--no-till corn: winter cover crop or winter fallow with residues
Corn-Red Clover Rotation--This
rotation is of particular advantage on strongly sloping fields. It is a
"short-term" rotation based on full utilization of the normally expected
two-year life of a red clover stand. It can be established in alternate
strips by growing two continuous years of no-till corn followed by two
continuous years of red clover. Or, if more forage is desired, it can be
established as a rotation among three strips (two clover and one corn).
The sequence for each strip of this three-year rotation would be:
• Year 1 --no-till corn followed by
a winter cover crop of small grain
• Year 2--overseed the small grain
in late winter with red clover, harvest the small grain as silage or grain,
then make two to three cuttings of red clover
• Year 3--take three to four cuttings
of red clover
• Year 4--rotate back to no-till corn
After getting the rotation fully established in units of three strips,
there would be one strip of corn, one strip of first year red clover, and
one strip of second year red clover occurring in sequence down the hillside.
rotation, though longer because of the longer life of an alfalfa stand,
is useful because of the high yields of high quality forage produced. These
high forage yields, when combined with the corn, will provide much of the
nutritive requirements for a dairy herd or other intensively fed livestock
enterprises. The rotation is set up in units of two strips. Alfalfa is
grown in alternate strips with no-till corn for as long as satisfactory
stands exist, at which time no-till corn is rotated onto the alfalfa strip.
No-till corn is grown continuously in alternate strips either into residues
from the previous year or into small grain seeded to provide winter cover.
Maintenance of Strips
Once strips are established, care should
be taken to maintain them in constant width to prevent formation of point
rows and over-planting onto an adjoining strip that may contain a different
herbicide. If desired, a strip off fescue sod just wide enough to mow,
can be established and maintained between each strip. Though lowering the
total planted acreage, these fescue "filter" strips can provide protection
on strongly sloping fields from slopewash of herbicides onto adjoining
strips. It is also very important to use herbicides or herbicide mixtures
that will not cause enough residual carry-over to damage the succeeding
crop to be grown in each strip. One of the most common problems encountered
in strip cropping is maintenance of sod waterways. Care must be taken when
applying herbicides to cut spray nozzles or spreaders off each time you
go across a waterway. Otherwise, sod will likely be killed and have to
Tilling and planting along slope contours
are effective methods in slowing surface water runoff and reducing erosion.
Effectiveness can be increased even more by using tillage methods that
leave at least some previous crop residues on the surface. A combination
of no-till and contour planting is perhaps the most effective system to
use in minimizing surface water runoff from sloping fields. And when these
two practices are incorporated into strip cropping and rotations, much
sloping land can be more intensively used for crop production with good
The greatest limitation to contour
planting and tillage is in fields with short, narrow slopes that break
in more than one direction. Planting on the contour in such fields results
in a great number of "point" rows that are a hindrance in field operations.
The best erosion control on such unevenly sloping fields comes with no-till