Natural Resources Conservation Service

Conservation Practice Standard

CONSERVATION CROP ROTATION

(Ac.)

Code 328

# DEFINITION

Growing crops in a recurring sequence on the same field.

# PURPOSES

This practice may be applied as part of a conservation management system
to support one or more of the following:

-   Reduce sheet and rill erosion.

-   Maintain or improve soil organic matter content.

-   Manage the balance of plant nutrients.

-   Manage plant pests (weeds, insects, and diseases).

-   Provide food for domestic livestock.

-   Provide food and cover for wildlife.

# CONDITIONS WHERE PRACTICE APPLIES

This practice applies to all land where crops are grown, except
permanent hayland, or other land use where annual row crops or close
growing crops are grown occasionally, only to facilitate renovation or
re-establishment of perennial vegetation. It does not apply to land
devoted to orchards, vineyards, or nurseries.

# CRITERIA

## General Criteria Applicable To All Purposes 

Crops shall be grown in a planned, recurring sequence as outlined in
Operation and Maintenance.

Crops shall be adapted to the climatic region, the soil resource, and
the goals of the producer. Adapted crops and varieties, listed in the
current edition of the Penn State Agronomy Guide and other appropriate
university publications or other approved sources, shall be selected.

A conservation crop rotation may include crops planted for cover or to
manage nutrients.

Crops shall be selected that produce enough above and below ground plant
biomass to control erosion within the soil loss tolerance (T) or any
other planned soil loss objective.

The Revised Universal Soil Loss Equation II (RUSLE II) erosion
prediction technology will be used to evaluate the effectiveness of the
cropping sequence to reduce erosion to acceptable levels. Calculations
shall reflect the effects of all conservation practices (both management
and support) in the conservation management system.

## Additional Criteria To Maintain Or Improve Soil Organic Matter Content

Crops shall be selected that produce the amount of plant biomass needed
to maintain or improve soil organic matter content, as determined using
the current approved Soil Conditioning Index score indicated by the
RUSLE II calculation.

If crop growth or residue is partially removed by baling or grazing, or
other methods, adequate residue shall be maintained to achieve the
desired soil organic matter.

Cover crops planted specifically for soil improvement may be harvested
or grazed, if adequate biomass is retained or other biomass is added to
achieve the desired level or soil organic matter.

## Additional Criteria To Manage the Balance of Plant Nutrients

Crop selection and sequence shall be achieved using an approved
budgeting procedure.

To reduce excess nutrients, crops or cover crops having rooting depths
and nutrient requirements that utilize the excess nutrients shall be
included in the crop sequence.

When crop rotations are designed to add nitrogen to the system,
nitrogen-fixing crops, including cover crops, shall be grown immediately
prior to or inter-planted with nitrogen depleting crops.

## Additional Criteria To Manage Plant Pests (Weeds, Insects, Diseases)

Crops shall be alternated to break the pest cycle and/or allow for the
use of a variety of control methods. Affected crops and alternate host
crops shall be removed from the rotation for the period of time needed
to break the life cycle of the targeted pest.

Resistant varieties, listed in current edition of the Penn State
Agronomy Guide or other appropriate sources, shall be selected where
there is a history of a pest problem.

Noxious weeds shall be controlled as required by Pennsylvania State law.

## Additional Criteria To Provide Food For Domestic Livestock

Crops shall be selected to balance the feed supply with livestock needs.
This balance shall be calculated when needed using appropriate
procedures. Private consultants, Cooperative Extension and others may
provide these calculations.

## Additional Criteria To Provide Food And Cover For Wildlife

Crop selection to provide either food and/or cover shall be determined
for the targeted wildlife species. Use an appropriate wildlife habitat
evaluation procedure as needed.

# Planning CONSIDERATIONS

When used in conjunction with the strip cropping practice (585), the
cropping system shall include crops and tillage systems that provide
alternate cover conditions that produce and trap sediment as defined in
the stripcropping practice standard.

When used in combination with residue management practices (329, 344,
345) and the selection of high residue producing crops, use of cover
crops, decreased row spacing, and increased plant populations can
enhance production of the kind, amount, and distribution of residue
needed.

Where maintaining or improving soil organic matter content is an
objective, the effects of this practice can be enhanced by managing crop
residues, tillage practices*,* utilizing animal wastes, or applying
mulches to supplement the biomass produced by crops in the rotation.

Where excess plant nutrients or soil contaminants are a concern,
utilizing deep rooted crops or cover crops in the rotation can help
recover or remove the nutrient or contaminant from the soil profile.

Where precipitation is limited, seasonal or erratic moisture can be
conserved for crop use by maintaining crop residues on the soil surface
to increase infiltration and to reduce runoff and evaporation. Where
winter precipitation occurs as snow, additional moisture can be obtained
for crop use by trapping snow with standing residue, windbreaks, or
other barriers.

Where improving water use efficiency on deep soils is a concern,
rotating or combining deep-rooted crops with shallow rooted crops can
help utilize all available water in the soil profile.

Crop damage by wind erosion can be reduced with this practice by
selecting crops that are tolerant to abrasion from wind blown soil or
tolerant to high wind velocity. If crops sensitive to wind erosion
damage are grown, the potential for plant damage can be reduced by crop
residue management, field windbreaks, herbaceous wind barriers,
intercropping, or other methods of wind erosion control.

Where pesticides are used, consider application methods and the crop
rotation to avoid negative impacts on the following crop due to residual
herbicides in the soil or adverse affects on aquatic wildlife or habitat
through runoff.

Soil compaction can be reduced by adjusting crop rotations to include
deep rooted crops that are able to extend to and penetrate the compacted
soil layers, as well as avoiding crops that require field operations
when the soils are wet.

Leaving several rows unharvested around the edges of the field will
provide protection and/or food for overwintering wildlife.

Crop plantings may be developed to benefit particular communities,
species or life stages of wildlife. Food plots or crops for wildlife
could be provided as part of a habitat restoration project as an initial
food and cover source for wildlife until food and cover producing
vegetation becomes established.

Crop residues may be a valuable food source for wintering wildlife where
winter browse is sparse.

Careful consideration should be given to pesticide use if applied to
crops raised for wildlife.

Where excess plant nutrients or soil contaminants are a concern,
utilizing deep rooted crops or cover crops in the rotation can help
recover or remove the nutrient or contaminant from the soil profile. The
use of the Nutrient Management practice (590) can also address this
issue.

# PLANS AND SPECIFICATIONS

Specifications for this practice shall be prepared for each field or
treatment unit according to the Criteria, Considerations, and Operation
and Maintenance described in this standard. Specifications should
include the cropping sequence, the numbers of years of each crop, and
the total length of the crop rotation. Specifications shall be recorded
using narrative statements in the conservation plan, job sheets, or
other acceptable documentation.

# OPERATION AND MAINTENANCE

Producers may need to modify crop rotations due to crop failure,
specific weather events, or economic conditions. Substitute crops should
have priorities similar to those in the planned rotation or adjustments
in planned tillage, residue management or the addition of cover crops
may be needed.

Proper adjustment, operation, and maintenance of equipment are essential
for successful implementation of this practice.

REFERENCES:

Agricultural Handbook 703, USDA Agricultural Research Service,
Washington, D.C., 1996.

Pennsylvania RUSLE Manual (PATG), USDA NRCS, Current Version.

National Handbook of Conservation Practices, USDA Natural Resource
Conservation Service.

Conservation Research Report No. 41., Crop Residue Management To Reduce
Erosion and Improve Soil Quality-Appalachia and Northeast, USDA
Agricultural Research Service, Washington, D.C., August, 1995.

Stubble Over the Soil: The Vital Role of Plant Residue in Soil
Management to Improve Soil Quality, Carlos Crovetto Lamarca, 1996.

Pennsylvania Noxious Weed Control Act of 1983, Pennsylvania Department
of Agriculture, Bureau of Plant Industry, 2301 North Cameron Street,
Harrisburg, PA. 17110-9408.

Building Soils for Better Crops, second edition, Fred Magdoff and Harold
van Es, Sustainable Agriculture Network, 2000.