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TOP STORY, July 25, 2017

Field day features subsurface litter injectors


Managing Editor

For more than a decade, a team of university researchers and engineers have focused on getting more out of poultry litter.
What’s now called the Subsurface Application of Manure or SAM Initiative looks to boost the use of liquid and solid manure injection technologies in high-density animal production regions of the Chesapeake Bay watershed.
Keyed to poultry litter injection, a field day at the University of Maryland’s Wye Research and Education Center brought four pieces of equipment in various stages of development to update farmers and industry representatives on the research and get feedback on moving the project forward.
Equipment in development from the University of Delaware, Penn State, Oklahoma State University and the USDA-Agriculture Research Service laboratory in Arkansas made the trip from near and far to give people an up close view of the implements and the changes that have been made.
“This is a national push,” said Dr. Josh McGrath, a University of Kentucky soil management Extension specialist involved in the SAM Initiative, who led the meeting. “Obviously here in the bay region water quality is probably the driving force in how we manage nutrients and how we manage manure.”
Research on building equipment to inject poultry litter into soil goes back to 2006 with a grant from the National Oceanic and Atmospheric Administration to launch the first “subsurfer” design. A series of annual grants followed to carry the project and the SAM initiative has sustained the research since 2014.
Many of the mechanical challenges have been overcome.
The injectors can apply the litter in away that instantly incorporates it into the soil in a consistent and adjustable way.
“Those problems we’ve generally solved,” said McGrath. “Now its become a challenge of getting the economics from an efficiency standpoint to where we need them.”
With the equipment’s current state, using the litter injectors come with many tradeoffs.
It can apply litter at a much more precise rate with better nitrogen utilization but travels slower, makes a narrower pass, meaning more time in the field and more wheel tracks which can lead to compaction.
A longer application time, McGrath said, could impact farmers, like those in Maryland, who are regulated in applying fertilizer in the spring.
Even if it works, it has to be economically feasible to do agronomic and environmental good, McGrath said.
“The best thing for the bay is a profitable farmer,” McGrath said. “Regardless of the rules, if it doesn’t work for the farmer at the end of the day, it’s not going to happen.”
Part of the economic feasibility is forming a support structure to aid early adopters to invest in the equipment, McGrath added, along with enlisting agricultural economists to further define the tangible benefits of injecting litter.
Three of the four litter injectors on display at the event, through different designs, fed the litter to the front of the spreader and drop it into soil openers as it moved in the field.
Discussing his injector from Arkansas, Dr. Dan Pote, USDA-ARS soil scientist, said it was initially focused on use in pastures but through several iterations, it’s been tested for use with other crops and in several places around the nation.
He said its key benefits are increasing nitrogen availability and decreasing ammonia volatilization and nutrient runoff.
The uniform application allows the operator to put litter, “wherever you want to place it,” he said. “It’s not the low-precision route you get with surface spreading application. It’s pretty consistent everywhere we’ve looked at this.”
Pote said particle size in the litter isn’t an issue in their prototype but it still should be “relatively free” of large foreign material like tools, a comment that spurred an impromptu chorus among researchers of things (bricks, wrenches, a crowbar) that have passed through the equipment leading to various repairs.
“If a farmer wants to look at using this, I definitely recommend they work on keeping that little as clean as possible,” he said.
He also recommended using litter less than 25 percent moisture for consistent flow of material.
“The drier it is the better it’ll feed into these openers,” he said.
Pote said their prototype had interest from one equipment manufacturer but the company was subsequently bought by another manufacturer and talk of commercialization ended.
Still, Pote said they pressing forward.
“By and large we feel like we’re far ahead of where we were with our early prototypes. We’re getting really close to what we think is a commercially viable product but we need to continue to work on some things,” he said.
McGrath said his research trials have shown a $60 to $70 per acre advantage in corn through better nitorgen utilization when testing a manure injector against a typical field application but there is still much to iron out before it could be commercially viable for farmers. Cost to a grower or custom applicator in buying an injector was only speculated upon.
The team from OSU took a pneumatic approach: Forcing the litter through tubes with air, similar to a seed drill, and into soil openers.
While John Long, OSU ag engineer, said their prototype is farther behind in development than other injectors, others in the crowd said it could have more promise for growers because the potential to apply on a wider pass and be more efficient.
“The team has really focused on the practicality of the equipment,” Long said. “You’re going to have to cover the same amount of ground they’re covering with sprayers. That’s what it comes down to.”