October 13, 2011
On Thursday, October 13, USDA’s Natural Resources Conservation Service (NRCS) issued the third study in the Conservation Effects Assessment Project (CEAP) cropland component. The cropland component is intended to quantify the effects of conservation practices on cultivated cropland in the lower 48 states. The Great Lakes CEAP examined the effects of conservation practices on water quality in the U.S. portion of the Great Lakes Drainage, which covers most of Michigan and parts of Wisconsin, upstate New York, Ohio, Indiana, Pennsylvania, and Illinois. Cultivated cropland covers about 24-percent of the 174,000 square mile drainage area.
The Great Lakes study includes data from 1400 USDA National Resource Inventory sample points with known soil profiles. Staff from the National Agricultural Statistics Service gathered information from farmers at these points about the crops produced, production methods, and conservation practices from 2003 to 2006. This information, along with U.S. Geological Survey water quality data, was fed into computer modeled simulations of conservation outcomes derived from the use of farming and conservation practices.
The results indicate that the use of conservation practices has reduced sediment loads delivered from cropland to the region’s rivers and streams by 50-percent compared to a scenario with no conservation practices. The reduction in total nitrogen loads from cropland to rivers and streams in the region is estimated at 37 percent and the reduction of total phosphorus from croplands to rivers and streams is estimated at 36 percent.
In addition, the study indicated that about 19 percent of the cultivated cropland – about 2.8 million acres – has a high loss of sediment and/or nutrients and a high level of need for conservation treatment. About 34 percent of the cultivated cropland has a moderate level of need for conservation treatment.
The biggest single resource concern according to the study is the loss of nitrogen from cultivated cropland through subsurface flows.
Another key finding of the Great Lakes study is that comprehensive planning and implementation are essential for dealing with sediment and nutrient loss from cropland. If conservation practices are focused only on sediment and erosion control, water laden with nitrogen is retained longer on the land. As a result nitrogen leaching to subsurface drainage increases. Erosion control and nutrient management measures must be used together for the optimum conservation outcome.
This finding is similar to the findings of the CEAP cropland study in the Upper Mississippi River Basin, released in June 2010, and the Chesapeake Bay Region study released in March 2011. NRCS expects to release reports on river basin cropland modeling in an additional 10 regions in 2012.
In addition to assessing the effects of conservation practices on cropland, CEAP studies are also examining conservation practice effects on pastureland and rangeland. Additional CEAP studies address conservation practice effects on wildlife and wetlands. The Project also includes indepth studies of conservation practices in 42 small watersheds. More information is available on the NRCS CEAP webpage.
Categories: Conservation, Energy & Environment