THE scientific community is calling for a collaborative effort among farmers, researchers and policy-makers within the Mississippi River Basin in order to reduce nutrient loading to the Gulf of Mexico.
Regardless of a 12-year action plan from the Mississippi River Gulf of Mexico Watershed Nutrient Task Force, biophysical and social barriers restrict water quality improvements from occurring in the Mississippi River Basin region, according to researchers from the University of Illinois and Utah State University.
The Gulf of Mexico hypoxic zone, the largest in the U.S., was first recognized in the early 1970s but was not intensely monitored until 1985. This year, the hypoxic zone was measured at 5,800 square miles, slightly above the five-year average and more than double the 2,000 square mile goal set by the task force (Figure).
In order to meet the target goal by 2015, there must be a 45% reduction in total nitrogen and phosphorus, which will require extensively implementing an array of nutrient reduction practices across the basin. The endeavor will not come cheaply and will require significant investment by governments and landowners.
Researchers Mark B. David, Courtney G. Flint, Gregory F. McIsaac, Lowell E. Gentry, Mallory K. Dolan and George F. Czapar authored an opinion piece — "Biophysical & Social Barriers Restrict Water Quality Improvements in the Mississippi River Basin," published Nov. 5 in Environmental Science & Technology — in which they identified the barriers and proposed future actions necessary to make progress on reaching the task force's goals.
"We are suggesting that a partnership of researchers work closely with farmers to develop the suite of practices that are needed to reduce nutrient losses from agricultural fields," said University of Illinois biogeochemist Mark David, who has been studying nitrate loss since 1993. "Working with farmers is essential to develop realistic practices on real-world farms — where the constraints that influence management are present — to document the effectiveness and to communicate the environmental and socioeconomic results regionally."
The researchers concluded that patterned tile drainage, increased corn production and more frequent high-intensity precipitation events all contributed to greater losses of nutrients and, consequently, a large hypoxic zone. This occurred even though nutrient balances have generally improved across the Upper Midwest.
The funding opportunities provided by federal agencies are particularly important to existing and future nutrient reduction efforts. The U.S. Department of Agriculture has invested more than $390 million in technical and financial assistance through various initiatives.
Fertilizer rate/time/placement, cover crops, nitrification inhibiters, water table management, tile bioreactors, constructed wetlands, buffer strips and conversion of row crops to the Conservation Reserve Program or perennial crops are among the array of techniques recommended by USDA's Natural Resources Conservation Service to reduce nutrient losses on agricultural lands.
"Unfortunately, few of these methods are used on tile-drained fields because they impose substantial costs and/or risks on the producers without increasing crop production," David said.
"For example, end-of-pipe practices such as tile bioreactors or constructed wetlands have substantial construction costs, require land to be taken out of production and provide no production benefit to the producer," he added.
Development of nutrient reduction plans in real farming scenarios is still needed.
In May, Iowa released its statewide nutrient strategy, which outlined the billions of dollars needed and the difficulty in implementing nutrient reduction practices.
In evaluating the potential practices to reduce nitrogen and phosphorus loading, the state looked at the cost of investment, operating expenses and lost production, plus the trade-off with other environmental concerns. However, practices that work well to reduce nitrates in groundwater may increase phosphorus in surface water.
As noted in Iowa's nutrient strategy, "While significant research has been conducted on the potential performance of various nutrient reduction practices, there is a need for development of additional practices, testing of new practices, further testing of existing practices and verifying practice performance at implementation scales. Additional research also would improve the predictability of practice performance and the understanding of practice uncertainty."
Additionally, in the opinion article, the researchers noted that socioeconomic factors hinder the adoption of farm conservation practices.
"Producers view themselves as stewards who care for the land, but they need to make a living from it," Utah State University rural sociologist Courtney Flint said. "Not only can they not see the loss of nutrients; they are disconnected physically from the downstream effects. Stewardship objectives may be strong, but they can be trumped or complicated by other economic, social and environmental drivers."
Furthermore, Flint added, "There is a growing sense among farmers that policy-makers are too far removed from the realities of farming."
It is the opinion of the researchers that an "ever-widening trust gap" exists that creates a barrier to successfully cooperate in policy development for Mississippi River Basin water quality improvements.
The researchers acknowledged that further research is needed to develop a suite of nutrient loss reduction practices that are practical for real-world farming. The effort will require farmers to actively participate with researchers and will take considerable funding in order to develop and implement effective programs, they concluded.