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Transformational Change Is Required to Meet Nutrient-Loading Reduction Goals

The uptick in conservation funding and practices comes from the driving force to improve water quality throughout the Midwest. However, no single practice will meet the nutrient-loading reductions set by the Mississippi River/Gulf of Mexico Hypoxia Task Force, explains Jim Jordahl, director of programs and operations for Iowa Agriculture Water Alliance. 

The Gulf Hypoxia Action Plan calls for states along the Mississippi River to develop strategies to reduce nutrient loading to the Gulf of Mexico – specifically, a minimum 45% reduction in total nitrogen (N) and total phosphorus (P) loads – in order to reduce the area of the hypoxia from nearly 6,000 square miles to 2,000 square miles or less, says Jordahl. 

Doing nothing isn’t an option. “Nitrates still get into the tile drains even if no N  or manure is applied,” says Jordahl. “That illustrates some of the difficulty we have in managing this system.”

Mother Nature is in the mix, too. A drought year followed by a wet year compounds the problem. 

The public’s perception that N fertilizer mismanagement is occurring is not the case, he explains. Soil microorganisms that process soil organic matter in warm and moist soils produce more nitrate than does fertilizer. 

“That said, nutrient management remains important both in terms of economics and to help us meet our water quality goals,” he says. 

The other piece of the puzzle is timing. The peak period of organic matter found within the intense cropping systems in the Midwest comes before the peak crop uptake of N, which results in potential leaching opportunities. 

“N fertilizer mismanagement is not the primary reason we see nitrate loss in the system,” says Jordahl. “The bulk of the loss is the mismatch between when nitrate is being produced within the soil and when our crops can take it up.”  

what to do

In Abbey Wick’s part of the world, the North Dakota State University soil health specialist sees farmers whose management practices are split between tillage practices. No-till has become a more common sight.  

“Farmers are now more interested in alternative ways to manage soils,” says Wick. 

Those practices will be instrumental in meeting the nutrient-reduction goals. One option is to adopt cover crops. 

“Cover crops can help to offset the N that the organic matter is producing that the crop can’t take up (during the mismatched timing) to minimize what is lost in the tile,” says Jordahl. 

They are a tool some farmers can use to recycle N instead of giving it the opportunity to wash down the tile lines. 

Another bonus is that cover crops provide ground cover that reduce erosion and can improve long-term soil health, says Jordahl. 

“We need a transformational change,” he says. “It’s not going to be little changes around the edges on management. No single practice will do it. It’s not just cover crops or just bioreactors or just wetlands or just no-till. It’s all of the above, depending on the field. The specific mix of practices will depend on the field and each farmer’s operation.”  

Conservation progress

The Iowa Nutrient Reduction Strategy 2016-2017 Executive Summary shows adoption of different conservation practices. The summary reported the following results. 

  • Through its grant program (since 2013), the Iowa Nutrient Research Center has funded over 30 projects with a primary focus on evaluating the performance of conservation practices in reducing nutrient loss from agricultural landscapes.
  • Land retirement through the CRP increased by 200,000 acres between 2015 and 2016 (excluding buffers and CRP wetlands). At 1.4 million acres, CRP land retirement is currently at about the same level as it was in 2011. 
  • Terraces, water, and sediment control basins have been constructed since 2011 to treat approximately 250,000 acres through government programs to reduce soil and P loss. Meanwhile, 36 N removal wetlands, treating 42,000 acres, have been installed since 2011. Approximately 100,000 total acres benefit from all 85 N-removing wetlands in the state.
  • Government cost-share programs enrolled 300,000 cover crop acres in 2016. The state has experienced a steady increase in cover crop acres since 2011, when cost-share acres were only at 15,000. In 2016, statewide estimates (beyond cost share) indicate 600,000 acres were planted.
  • At least 88% of Iowa’s land drains to a location with water-quality sensors installed and maintained mainly by the Iowa DNR, University of Iowa IIHR–Hydroscience and Engineering, and the U.S. Geological Survey.Water monitoring occurs at various scales, from edge-of-field sites to large watersheds. Also, surface water grab samples are collected regularly by the Iowa Soybean Association and Agriculture’s Clean Water Alliance in 187 locations, plus 435 edge-of-field sites. 
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