Bay Journal

Intimidator, subsurfer latest tools to hammer away at nutrient pollution

Researchers developing new methods to deliver exact amount of fertilizer to soil exactly when it is needed

  • By Rona Kobell on March 01, 2010
  • Comments are closed for this article.
Peter Kleinman a soil scientist with the U.S. Department of Agriculture’s Agriculture Research Service, explains how the manure injector ( which prevents liquid manure from leaching into the subsoil., foreground, and intimidator (background) work on the UMES farm in Princess Anne, MD. (Dave Harp) Tony Buda, a hydrologist with the Department of Agriculture's Agriculture Research Service, walks along a gypsum curtain and sampling wells adjacent to a farm ditch at the UMES farm in Princess Anne. (Dave Harp) Don Mahan, an agricultural technician at University of Maryland-Eastern Shore, takes water samples from a lysimeter in a cornfield at the UMES farm. (Dave Harp) Peter Kleinman, a USDA ag research service soil scientist, stands near a flume that measures nutrients in surface runoff in a corn field. (Dave Harp)

With names like The Intimidator and The Subsurfer, the equipment on this one-time poultry farm near Princess Anne on Maryland's Eastern Shore looks and sounds like it could star in an action movie.

Instead, these tools are on the front lines of research developing the next-generation nutrient-management practices that will help farmers control erosion and reduce the amount of nitrogen and phosphorus running into waterways.

Together, these pieces of equipment, and others like them, are setting out to do what has yet to be done: Precisely apply dry poultry manure into a part of the soil where the nutrients within it won't run off, and monitor it to make sure it stays there. If everything goes according to plan, the technology could come to market in just three years.

"It's a big breakthrough," said Peter Kleinman, a soil scientist with the U.S. Department of Agriculture's Agriculture Research Service who is based at Penn State University. "With dry manure, the holy grail had been, 'how do you get it into the soil without tillage?'"

By weight, there is much more wet manure, from dairies and large animal feedlots, than there is dry manure from poultry. So solving this problem doesn't solve all of the manure disposal problems that farmers face, but it does address one that has been particularly difficult.

Kleinman is one of several federal researchers based at Penn State who are trying to identify the future's best-management practices for farmers, and then make them available across the Chesapeake Bay watershed-a process that can take up to 15 years and cost millions of dollars.

Recognizing the urgency to control runoff from agriculture-the largest single source of nutrient pollution to the Chesapeake-the draft federal strategy for protecting and restoring the Bay, developed in response to President Barack Obama's Chesapeake Bay executive order, called for the EPA and USDA to work together to accelerate the development and farmer adoption of the "next generation of conservation planning tools."

The challenge of their work is illustrated by the ongoing debate among scientists in the watershed about how to tackle the problem of phosphorus in the soil. Some believe the federal government should pass a national standard-a single, universally applied number based on the results of a soil test-that would limit how much phosphorus farmers can apply. Others prefer an approach called the Phosphorus Index-or P-index-which considers factors such as soil type and proximity to waterways before calculating how much phosphorus the soil can take. The federal government considered introducing a standard late last year, but decided instead to refine the P-index to better reduce phosphorus. (See "Proposed national standard for phosphorus derailed by critics," February 2010.)

In the meantime, the search continues for better practices to keep nutrients out of waterways. Many of the practices farmers already employ have helped. These include cover crops, grass waterways, and not tilling the soil. Yet, of all the land uses, agriculture still delivers the largest loads of pollution to the Bay.

The Penn State group is conducting its work on four farms in the region; each represent the types of soils and problems common to that locale.

The Maryland farm, which is owned and operated by the University of Maryland-Eastern Shore, is typical of the Delmarva Peninsula: sandy soils, lots of poultry manure and legacy pollution from too much phosphorus applied on the land. Students from UMES, a short drive away in Princess Anne, assist UMES faculty in the experiments.

The New York farm is in Stanford, in the Allegheny Plateau and in the New York City watershed. It is just outside of the Chesapeake watershed in the Catskill Mountains. There, researchers have been encouraging farmers to adopt basic practices, such as cover crops and stream bank fencing to keep livestock from wandering into waterways.

In Central Pennsylvania, the researchers maintain one test farm in the Mahantango watershed, which they have been working on for several decades, and another one close to State College.

A fifth site is just getting started in the Conewago watershed, which includes parts of Lancaster County, PA, one of the watershed's hot spots for manure pollution. This site will not only focus on getting farmers involved in controlling pollution, but also engage suburbanites, urbanites and local governments.

At the farm close to the Penn State campus, USDA ARS soil scientist John Schmidt is developing a nitrogen sensor that, if widely adapted, could result in huge decreases in the amount of fertilizer applied. And, Schmidt said, a lot less work for the farmer.

Under the current setup, a farmer applies fertilizer to his fields, lets the crop grow a bit, then does a soil test to determine how much more he will need to get the maximum yield. At that point, the farmer has a brief window to reapply fertilizer, and might run into unexpected problems such as bad weather. Also, if the corn has grown too high, the farmer may need special equipment to access it.

This scenario is not only a lot of work for the farmer, Schmidt said, but results in too much nitrogen applied, because the farmer is going for the maximum yield when instead he should seek the "optimum yield," which factors in how much yield he can get per the amount of fertilizer applied. In an effort to get a small fraction more in yield to reach his maximum, Schmidt said, the farmer will apply much more nitrogen than the plant needs and it will leak in the ground.

Enter the sensor. A farmer can put sensors out in a field that send information about the soil to a computer in the tractor. The computer calculates how much fertilizer to apply, then sends that information to the applicator, which shoots it onto the ground.

Right now, the sensor is only used for synthetic fertilizer. Schmidt has been testing the sensor with farmers in Northcentral Pennsylvania since 2005. Several companies sell models of applicators with the sensor in other parts of the country, but they haven't caught on here. And, Kleinman said, those models are based on maximizing yield, rather than finding the sweet spot at which the greatest amount of crop is produced for the least amount of nitrogen.

In Princess Anne, Kleinman and his colleagues are tweaking The Intimidator, a drop hammer attached to a tractor that drives columns into the ground. After that, the subsurfer comes along, depositing poultry manure in the subsoil-the strata under the top layer-which is not prone to run off. The researchers then bury the columns and conduct normal field activities over them while the columns collect water. The researchers come through later and collect the columns to test the phosphorus levels in the water, which tells them about short-term and long-term trends. It's a common practice in the watershed to put fertilizer down and not till it, a strategy that stems erosion and saves labor. But it also promotes runoff and fertilizer nutrient loss, because the nutrients aren't pushed into the soil.

Unlike the sensor, which creates less work for the farmer, the subsurfer creates more, because the farmer has to drive more slowly to pull the implements through the ground. But Kleinman is optimistic that farmers will adopt it, if only because the researchers saw a 30 percent greater yield using the subsurfer.

"The liability of going slower is totally outweighed by the benefits," Kleinman said.

One practice that could become standard quickly is the use of a gypsum curtain. For years, scientists have known that gypsum, which is calcium sulfate, absorbs phosphorus well. Ray Bryant, another ARS soil scientist who works at Penn State, decided to see if gypsum could be used to improve water quality on a phosphorus-rich poultry farm. He put a gypsum screen up to divide a ditch that flows into the Manokin River on the UMES farm. On one side of the curtain, the water is filled with algae fueled from phosphorus. On the other side, it's not.

Bryant, along with his UMES partners, decided to take the approach further. They dug what looks like a landing strip between a soybean field and a waterway and placed gypsum under it. Half of the waterway has a gypsum curtain between it and the field, the other half doesn't. Bryant said the researchers should know if the curtain is reducing phosphorus in the water in a couple of months.

If it works, the farmers in the watershed just might go for it, said Hank Zygmunt, the agricultural adviser for EPA's Region Three. Zygmunt visited the farm in January with several EPA officials and was impressed by what he saw.

"This type of design, if it's going to work, will be a lot more palatable to farmers than a 35-foot buffer," he said.

Gypsum is also cheap and easy to get. A byproduct of the process to remove sulfur from coal-fired power plants' flue gases, Bryant said, "gypsum is something industries want to get rid of." Farmers are already using mined gypsum to give their soil calcium and make it easier to work. He's hoping the USDA's National Resource Conservation Service will share the costs of gypsum curtains, with farmers.

One person watching the UMES experiments closely is Kristen Saacke-Blunk, director of Penn State's Agriculture and Environment Center. Her team recently received a $750,000 grant from the National Fish and Wildlife Federation to study and implement pollution reduction techniques in the Conewago watershed. Half of the 53-square mile watershed is farmland and 30 percent is forest. The rest is residential. Saacke-Blunk said that part of the idea is to get everyone thinking about practices that can reduce nitrogen and phosphorus from entering the Bay. Working with the local watershed association, conservation districts, townships, colleges and the federal and state government, the Conewago project will target "the groups of people who have not been early adapters," Saacke-Blunk said.

"Every single individual who lives and works within this watershed has some level of responsibility. The beauty of this project is that we have a lot of partners working in one place who are excited about building a utopia of [pollution-reducing practices]," she added. "For any landowner, whether it's a farmer or a homeowner, it's a question of what are you willing to do?"

About Rona Kobell

Rona Kobell is a former writer for the Baltimore Sun. .(JavaScript must be enabled to view this email address).

Read more articles by Rona Kobell

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