Crop Residue Management and Tillage Definitions
Crop residue management (CRM) is a year-round conservation
system that usually involves a reduction in the number of passes
over the field with tillage implements and/or in the intensity of
tillage operations, including the elimination of plowing (inversion
of the surface layer of soil). CRM is in sharp contrast to conventional
tillage systems that rely upon the moldboard plow or other intensive
tillage, and which have little or no management of residue.
CRM begins with the selection of crops that produce sufficient
quantities of residue to reduce wind and water erosion and may include
the use of cover crops after low residue-producing crops. CRM includes
all field operations that affect residue amounts, orientation, and
distribution throughout the period requiring protection. Site specific
residue cover amounts needed are usually expressed in percentage
but may also be in pounds. Tillage systems included under CRM are
conservation tillage (no-till, ridge-till, and mulch-till) and reduced
tillage.
Conservation tillage—Any
tillage and planting system that covers 30 percent or more of the
soil surface with crop residue, after planting, to reduce soil erosion
by water. Where soil erosion by wind is the primary concern, any
system that maintains at least 1,000 pounds per acre of flat, small
grain residue equivalent on the surface throughout the critical
wind erosion period. Two key factors influencing crop residue are
(1) the type of crop, which establishes the initial residue amount
and its fragility, and (2) the type of tillage operations prior
to and including planting.
Conservation Tillage Systems Include:
No-till—The soil is left undisturbed from harvest
to planting except for nutrient injection. Planting or drilling
is accomplished in a narrow seedbed or slot created by coulters,
row cleaners, disk openers, in-row chisels, or roto-tillers. Weed
control is accomplished primarily with herbicides. Cultivation
may be used for emergency weed control.
Ridge-till—The soil is left undisturbed from
harvest to planting except for nutrient injection. Planting is
completed in a seedbed prepared on ridges with sweeps, disk openers,
coulters, or row cleaners. Residue is left on the surface between
ridges. Weed control is accomplished with herbicides and/or cultivation.
Ridges are rebuilt during cultivation.
Mulch-till—The soil is disturbed prior to
planting. Tillage tools such as chisels, field cultivators, disks,
sweeps, or blades are used. Weed control is accomplished with
herbicides and/or cultivation.
Reduced tillage (15-30% residue)—Tillage types
that leave 15-30 percent residue cover after planting, or 500-1,000
pounds per acre of small grain residue equivalent throughout the
critical wind erosion period. Weed control is accomplished with
herbicides and/or cultivation.
Conventional tillage (less than 15% residue)—Tillage
types that leave less than 15 percent residue cover after planting,
or less than 500 pounds per acre of small grain residue equivalent
throughout the critical wind erosion period. Generally includes
plowing or other intensive tillage. Weed control is accomplished
with herbicides and/or cultivation. Conventional tillage systems
include:
Conventional tillage with moldboard plow—Any
tillage system that includes the use of a moldboard plow.
Conventional tillage without moldboard plow—Any
tillage system that has less than 30 percent remaining residue
cover and does not use a moldboard plow.
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