Early poultry litter injectors, bottom photo, operated by dropping pulverized litter into row units of disc openers and closing wheels, The design has evolved to be similar to an air seeder, blowing litter from a central hopper through tubes to individual row units, top photo. These prototypes were demonstrated at a 2017 field day at the University of Maryland’s Wye Research and Education Center. (Delmarva Farmer file photos)
As a concept, poultry litter injection appears to be an elegant solution on Delmarva.
It preserves the benefits of no-till with minimal soil disturbance, puts the litter in the soil which reduces ammonia volatilization and nutrient runoff and uses a locally-made natural fertilizer in an efficient way.
After more than 10 years of research, challenges remain in getting to the point of commercializing equipment, but researchers are steadfast in the pursuit.
During a Feb. 25 webinar hosted by the Delmarva Land and Litter Collaborative, researchers involved in the injector’s creation and refinement discussed their progress and goals going forward.
With liquid manure injection available commercially and gaining wider use in the industry, Kristen Hughes Evans, DLLC vice chairperson who moderated the webinar said it’s a “big deal” to reach the same point with poultry litter.
“It’s a big deal for both farmers’ finances and for water quality,” she said. “We know that nitrogen prices are at crazy levels right now and if you’re injecting manure you’re capturing that nitrogen, you’re improving the nutrient use efficiency of your poultry litter. Also it’s estimated that on most of Delmarva in the coastal plain regions we’re going to reduce nitrogen loss to surface waters by 12 percent and phosphorus loading by 22 percent.”
Reviewing the history of litter injector research, Dr. Josh McGrath, University of Kentucky Extension soil management specialist, said iterations of the injector design shifted from dropping pulverized litter into row units of disc openers and closing wheels, to a high-pressure air system, blowing it through hoses to row units.
The early versions proved effective in getting litter into the soil but had considerable drawbacks compared to surface applicators.
“You have fast and cheap with a surface applicator versus slow and expensive with an injector and so will the benefits of the injector balance the cost?,” McGrath asked.
To increase it’s benefit, McGrath and Dr. Amy Schober, University of Delaware Extension nutrient management specialist, looked at treating the litter with nitrapyrin, a nitrification inhibitor prior to injection and saw “huge benefits,” McGrath said.
“In the lab we saw that basically surface applied litter we could get the same yield with 84 pounds less nitrogen at sidedress.”
Without cutting the rate, yield increased 16 bushels per acre in the lab study, McGrath said.
“So if you balance those two we could get you know about 15 more bushels to the acre with almost 80 pounds less nitrogen with injection so clearly there is some upside here but there was a lot of drawbacks as far as the machinery.”
Yet, with a limited amount of suitable planting days in the spring, the injectors appeal would largely depend on how well it could stay ahead of the planter.
To become competitive agronomically with surface applicators, McGrath cited a UK graduate student’s research that an injector would have to increase its capacity from 3.25 to about 20 acres per hour, bring its purchase cost down from $50,000 to about $10,000 and show its use will increase nutrient efficiency by 7 to 10 percent.
“Now any one of these alone would have made the litter injector competitive with surface application but balancing the combination of those three would also do it. Because obviously we’re not going to make a machine probably for $10,000 but maybe we get the price down some and get close to that 20 acres per hour and get a nitrogen benefit of about 10 percent and then we’d be very competitive.”
University of Georgia researchers have the 20 acre per hour goal in their sights, building on the high-pressure air system developed at Oklahoma State University.
UGA Extension specialists Simmerjeet Virk and Wes Porter said they are first focusing on improving distribution accuracy through precision rate control and metering the litter at the central hopper and at row units.
“There are other machines that deliver litter to or just below the surface of the soil but no current machine treats and accurately meters and that’s kind of critical here,” Porter said.
The Georgia team is using 3-D modeling and printing technology to first build a mini-version of an injector, test it at the lab scale and then further develop it for field testing.
“When we talk about that precision rate control, we’re basically looking at what we need to be able to apply to reach that greater than 20 acre per hour parameter and then we’re going to work backwards from there so that we know that we’re measuring or able to engineer and meter at that rate accurately.”
That includes testing working with litter of varying compositions to be able to accommodate materials from different poultry growing regions. How much and what kinds of pre-treatment the litter will need before it goes in the system is also a research component, Porter said.
With an accurate metering system in place, Porter said adding sensors at row units could bring even more precision.
“Right now we can monitor seed as it’s falling down the tubes and we’re hoping to get to that point with poultry litter eventually and so we’ve got to keep in mind the width and the speed of travel or maybe a combination of both so that we can get some of these plants,” he said.
Porter added their goal is to have a machine “which we can deliver to industry partners poised for commercial development” in about five years.
“This is a holistic project,” he said. “I want you to keep that in mind that though as we go piece by piece we’re looking at the whole machine.”
