Gulf’s Enduring Nutrient Problems Difficult To Fix

As in the Chesapeake Bay watershed, the federal government has stepped in to speed progress in the Gulf of Mexico’s water quality dilemma. EPA’s goal is reduce the size of the hypoxic “dead” zone by two-thirds by 2035. Ellen Gilinsky, the agency’s Senior Advisor for Water, says that will require a 45% reduction in the amount of nitrogen and phosphorus entering the Mississippi River.

Conservation efforts over the last three decades have not been able to shrink the zone substantially, even though many stakeholders have joined the work. Part of the problem: The Mississippi-Atchafalaya River Basin (MARB) is just so huge. Waterways spanning 31 states and two Canadian provinces here ultimately drain into the Gulf of Mexico.

Advertisement

Voluntary practices to reduce nutrient entering the basin waters have been going on for years, particularly in the 12 states along the Mississippi and Ohio Rivers. All of these states have developed nutrient reduction strategies under EPA’s 2008 Hypoxia Action Plan.

Top Articles
Best Agriculture Apps for 2024 (Update)
Howard Brown GROWMARK

Howard Brown

Howard Brown, Director of Nutrient Management and Environmental Stewardship with GROWMARK says progress will be realized not simply with a reduction of use but with utilization of what is applied. This philosophy drives many of the practices growers are using today to control fertilizer loss. Practices that other water stakeholders are willing to help implement.

On The Ground

Brown highlights some of the challenges growers can face in reduction efforts. For instance, the growing environment can easily override any best efforts to manage N. A grower can apply his entire N post-emerge, when the plant is most likely to use it. But if it doesn’t rain after the application, as happened in 2012 in many areas, the N won’t get into the plant (low yield), leaving the entire late-applied N in the upper soil profile after harvest when it will likely be lost by leaching (into subsurface tile lines) or by denitrification.

Then too, growers can apply N in the fall of the year, when the soils are cooling down and use a nitrification inhibitor to help maintain N in a stable form. Unfortunately, a warm-up of soils from November into late December (like many experienced last year) can contribute to an earlier-than-expected conversion of stable ammonium-N into nitrate-N, a form that can be lost with spring rains (leaching and/or denitrification).

Even with BMPs utilized last fall with delayed N applications and the use of nitrification inhibitors, close to 50% of the detected plant-available N in the upper two feet appears to be in nitrate-N, a form that can be easily lost with the spring thaw and significant rain events.

GROWMARK’s commitment to nutrient stewardship can be seen in the company’s new branded M.O.M. program — Minimizing environmental impact by Optimizing harvest yield and Maximizing input utilization.

What does M.O.M. look like? Brown shares an example. Five years ago a common N application in the upper Midwest was fall-applied anhydrous ammonia without any nitrification inhibitor. Today, it’s not uncommon to find the same growers splitting N into two or more applications, reducing fall application while adding an N stabilizer, and adding a post-emerge (side-dress) application as part of an N management system.

GROWMARK has also created a tool that allows the grower to watch the plant-available N in the soil over time. Called N-WATCH it provides a way for growers to inventory, track, and verify plant-available N at one point in the field over time. It can be used with Climate Corp.’s N-Advisor.

Use of N-WATCH on over 80 field sites was actually sponsored by the Iowa Farm Bureau in 2015, says Brown. And the Illinois Council on Best Management Practices supported the Sentinel Site Program in 2015 that allowed N-WATCH Site data to be posted online for other non-participating growers to track changes in plant-available N from sites closest to their operations. Growers could view N-WATCH reports from close to 200 sites across Illinois and receive an email alerting them when new site data was posted.

Strong Support Systems

For more than 20 years, a key supporter and facilitator of vital networking further down the Mississippi River has been Delta F.A.R.M. (Farmers Advocating Resource Management). The group acts as a “mediator” between different agencies and specialists, says Trey Cooke, executive director. Its goal is to come up with comprehensive regional solutions to natural resource problems that empower agriculture (including its profitability) as well as sustain resources.

Trey Cooke

Trey Cooke

The group’s list of partners is long: NRCS, FSA, DEQ, Fish and Wildlife Services, soil and water conservation districts.

In Delta F.A.R.M.’s sphere of influence — the lower Mississippi Valley — nitrogen is not the problem. In fact, because of the area’s subtropical climate, something is always growing in soils (bacteria, fungus, plants, weeds) and utilizing it, so very little nitrogen/nitrates/nitrites make it to the Gulf.

“But according to USGS, we are major contributors of phosphorus,” says Cooke. “Our phosphorus is tied to the soil, so fundamentally the biggest nutrient reduction activity we can engage in here in the Delta is to stop sediment. It’s erosion control in the form of simple, basic conservation.”

Structural practices to help can include landforming and building pads with water control structures for drainage around fields. Cooke says these measures are engineered to reduce erosion regardless of a field’s production systems.

0
Advertisement