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CEAP National Assessment: Cropland
The Cropland Component of the CEAP National Assessment includes land enrolled in the
Conservation Reserve Program (CRP). Formerly cropped wetlands will be included in the
Wetlands Component. Wildlife benefits of cropland conservation practices will be
addressed in the Wildlife Component.
Purpose
The purpose of the national assessment for cropland is to estimate the environmental
benefits for conservation practices applied to cropland, including cropland enrolled in
the Conservation Reserve Program.
Goals
The Cropland Component of the National Assessment has four specific goals:
- Estimate the benefits of conservation practices currently present on the landscape.
- Estimate the need for conservation practices and the benefits that could be realized if appropriate conservation practices were implemented on all cropland.
- Simulate alternative options for implementing conservation programs on cropland in the future.
- Incorporate science-based estimates of practice benefits into NRCS’s Performance Reporting System (PRS)
to provide annual estimates of benefits for each program.
The ultimate goal of the Cropland Component is to report benefits in terms that represent recognizable outcomes, such as
cleaner water, more efficient consumption of irrigation water, and soil quality
enhancements that will result in more sustainable and profitable production over time.
The primary focus is on water quality, soil quality, and water use conservation.
Approach
The Cropland Component uses a sampling and modeling approach to estimate the
benefits of conservation practices. The approach consists of four basic steps
or activities:
- First, a subset of National Resources Inventory (NRI) sample points has been selected
to serve as "representative fields." NRI sample points provide the statistical framework for
the model as well as information on soils, climate, and topography.
- Second, USDA developed and implemented a new farmer survey to collect the information needed
at the selected NRI sample points to run field-level process models and assess the effects of
conservation practices. The National Agricultural Statistics Service (NASS) interviews
cooperating farmers to obtain current information on farming practices (crops grown, tillage
practices, nutrient and pesticide application, conservation practices, etc.)
- Third, USDA will use the physical process model called APEX (Agricultural Policy Environmental Extender) to estimate field-level benefits.
APEX is a variant of the EPIC (Erosion Productivity Impact Calculator) model that allows us to estimate the effects of buffers, grassed
waterways, and other erosion control practices. APEX allows estimation of the reductions in
soil loss, reductions in nitrogen loss, reductions in phosphorus loss, and reductions in
pesticide loss from farm fields. Pesticide loss will be expressed as reductions in pesticide
risk. APEX will also allow us to evaluate soil quality enhancement as a result of practice
implementation.
- And finally, CEAP is integrating the model output from APEX with another model called
SWAT/HUMUS (Soil and Water Assessment Tool / Hydrologic Unit Model of the U.S.) to assess off-site benefits for water quality. HUMUS includes databases on land
use and sources of non-point and point source pollutants that are used with the SWAT model
to simulate the transport of water and potential pollutants
from the land to receiving streams, and routes the flow downstream to the next watershed and
ultimately to the estuaries and oceans. SWAT/HUMUS allows estimation of the reduction in
in-stream concentrations of sediment, nutrients, and pesticides attributable to implementation
of conservation practices.
The findings of the CEAP Watershed Assessment studies will be used to refine the methods
and models used in the National Assessment for cropland to estimate benefits of conservation
practices.
Reports
Work plan
Presentations
These documents require Acrobat Reader.
Contact
Robert Kellogg
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