June 16, 2010
Growers can pat themselves on the back after reading new survey results from the USDA-NRCS. The study finds plenty of positives, and plenty yet to work on, after surveying conservation practices on environmental quality in the Upper Mississippi River Basin (UMRB). Nearly half the basin is planted in corn and soybeans.
“Incorporating the 4 Rs of nutrient stewardship – right source, right rate, right time and right place – into a farm’s system of practices will move us toward the goal,” commented Karen Scanlon, executive director of the Conservation Technology Information Center, a group that’s counseled farmers on conservation practices for 20 years.
Key findings from the study, "Effects of Conservation Practices on Cultivated Cropland in the Upper Mississippi River Basin" include:
Groups or suites of conservation practices work better than single practices.
Targeting highly erodible acres improves effectiveness by 300-500%. It reduces sediment loss by more than 500%; nitrogen (N) loss by over 400% and phosphorus loss by over 300%.
Soil erosion-control practices are widespread in the UMRB. Most acres have some sort of conservation treatment, resulting in a 69% reduction in sediment loss. However, about 15% of the cultivated cropland acres still have excessive sediment losses and require additional treatment.
Conservation practices reduced total phosphorus loss by 49% in the study, but they reduced N losses by only 18%.
Pesticide risks to human health was reduced by conservation practices by 48%. Only 1-2% of pesticides applied are leaving fields. Much can still be done to reduce this further: rotations, scouting and precision application.
The loss of N from farm fields through leaching, including through tile drainage systems, is the most critical conservation concern. Surface N losses were reduced by 46%, but subsurface losses are reduced by only 5%. Comprehensive planning is needed to reduce this subsurface N loss.
About 60% of the cropland needs nutrient management, but the way in which nutrients are applied can be improved. Nitrogen is applied at 1.4 times removal at harvest on 66% of the cropland, the study found.
Nitrogen is not incorporated, banded or foliar/spot-treated on 44% of the cropland acres studied.
In-stream sediment was reduced by 37% compared to no conservation practices.
Opportunities to improve conservation practices on cropland include:
Consistent use of nutrient management (proper rate, form, timing and method of application) is generally lacking throughout the region. Improved nutrient management would reduce the risk of nutrient movement from fields to rivers and streams. A suite of practices that includes both soil erosion and consistent nutrient management is required to address soil erosion and nitrogen leaching loss.
Additional information is needed to implement targeted conservation measures, including soil leaching and run-off vulnerability maps, stakeholders’ input, water-quality monitoring data and small watershed modeling.
Cropland is sequestering carbon. In the UMRB, it sequesters about 7.5 million tons of CO2-equivalents annually. This offsets the combustion of 0.75 billion gallons of gas, enough gas to power about 1.3 million cars for one year.
The average cropland acre, with existing conservation, gains an annual net of 259 lbs. of CO2-equivalent.
"Farmers and ranchers are stepping up and implementing conservation practices that have a significant impact on the health of America's soil and water," says Agriculture Secretary Tom Vilsack. "This study will quantify the effectiveness of conservation practices for the first time and enable USDA to design and implement conservation programs that will meet the needs of farmers and ranchers, and ensure that taxpayers' conservation dollars are used as effectively as possible."
This study is part of a larger effort – the Conservation Effects Assessment Project (CEAP) – to assess the effects of conservation practices on the nation's cropland, grazing lands, wetlands, wildlife and watersheds. CEAP is a multi-agency, multi-resource effort led by USDA's NRCS. Additional regional cropland studies on the effects of conservation practices will be forthcoming over the next several months.
The complete UMRB cropland study report can be found online.
The area studied – the UMRB – covers about 190,000 square miles (121.5 million acres) between north-central Minnesota and the confluence of the Mississippi and Ohio rivers. The basin includes large portions of Illinois, Iowa, Minnesota, Missouri and Wisconsin and small portions of Indiana, Michigan and South Dakota.
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