A machine that can inject dry poultry litter and composted cattle manure below the soil surface in pastures and no-till fields is on order from a research coalition across five Chesapeake Bay states: Delaware, Maryland, Virginia, Pennsylvania and New York. There are currently no machines on the market that can do this.
The coalition is led by U.S. Department of Agriculture (USDA) scientist Peter Kleinman, who along with research partners at Pennsylvania State University and Virginia Polytechnic Institute and State University received a $786,000 grant to test four prototypes of the Poultry Litter Subsurfer.
Soil scientist Dan Pote, at the ARS Dale Bumpers Small Farms Research Center in Booneville, Ark., invented the Subsurfer, which injects litter with the minimal soil disturbance required by no-tillers. The Subsurfer can carry up to 5 tons of litter for application below the surface of pastures without damaging the grass, much as a no-till planter places seeds. It can also apply poultry litter below no-till fields before planting.
In tests on Arkansas pastures, Pote found that the Subsurfer lowers nutrient runoff and ammonia emissions by at least 90% while increasing forage yields. Kleinman and colleagues documented lower phosphorus runoff and ammonia loss and greater corn yields in Maryland and Pennsylvania. Jack Meisinger, an ARS soil scientist in Beltsville, Md., also reported lower ammonia losses.
As a collaborative project, Pote led development of the Subsurfer, while agricultural engineer Tom Way's team at the ARS National Soil Dynamics Laboratory in Auburn, Ala., focused on developing a different prototype with adjustable row spacing for litter application in row-crop systems and pastures.
The two machines have such different delivery systems that Pote and Way sought different patents. Pote's Subsurfer uses a unique auger system that crushes litter and distributes it to soil trenches, allowing precise control, including low rates not previously feasible. His tractor-drawn Subsurfer carries up to 5 tons of litter and simultaneously opens eight trenches (2 inches wide and 3 inches deep), with 1 foot between each trench.
ARS is applying for U.S. and international patents on Pote's Subsurfer. One company has applied for a license to commercialize it. Way's invention has been patented.
Poultry litter is an excellent source of crop nutrients, but the common practice of spreading it on the soil surface promotes odor emissions, exacerbates nutrient runoff to nearby waterways — most notably the Chesapeake Bay — and allows ammonia nitrogen to evaporate. By minimizing nutrient losses, farmers can improve air and water quality and increase crop productivity.