Viability of Compost Treatments for Cropland to Be Examined in Longmont Area
Whether processed organic compost can be used as an alternative to synthetic fertilizers to boost the health of farmland soils is being explored in a field just south of Longmont.
Through a study Boulder County is funding in partnership with Colorado State University, 20 acres along the south side of Quicksilver Road from North 119th Street to East County Line Road will be covered with compost next month. Its effects on soil health will be monitored for at least a year and maybe longer.
The field, 140 acres in total, is owned by Boulder County and farmed by Paul Schlagel, whose family has farmed in the Longmont area for more than four generations. It currently has sorghum chopped and lined in rows ready to be collected and fed to cows on a dairy farm.
As much as 18 tons of compost per acre could be applied to the 20 acres of field being examined as part of the study once the sorghum is picked up.
But questions remain surrounding the economic viability of widespread agricultural compost applications, since synthetic fertilizers are currently less expensive.
If, however, the study shows that putting compost on either irrigated cropland or grazing ranges for livestock bolsters levels of organic materials in soil over the long run — so fertilizers would be required less often and more water could be retained in fields, thus saving farmers on overhead — supplies of compost within and near Boulder County would be quickly gobbled up.
“I think from the soil health perspective, the compost is adding something that the synthetic fertilizer really can’t. ... It’s going to help the structure of the soil,” Boulder County Agricultural Resources Manager Blake Cooper said.
He said about $186,000, some of which will be used to purchase compost, has been set aside by the county to participate in the study with CSU.
Manure less available, more costly
Finding alternatives to manure from cattle feed lots and dairy farms to use as organic fertilizer has become necessary for Boulder County agriculturalists.
Too few cattle feed lots are located close enough to Boulder County to make obtaining manure from them cost-efficient for farmers here, and manure from nearby dairy operations tends to be of lower quality than that from feed lots.
“A couple years ago, we started hauling dairy manure. It wasn’t cost effective, we just had to haul it too far,” Schlagel said. “The quality of dairy manure is so diluted with straw and stuff.”
The study that will look at the effects of compost on the field farmed by Schlagel is entering its second phase. As part of the first, CSU researchers in February recommended the county’s open space farmers implement several techniques in addition to compost applications to further sequester carbon-based greenhouse gases from entering the atmosphere.
Planting fall cover crops was another carbon sequestration strategy researchers urged farmers tending Boulder County-owned open space to use.
Local compost production needed
In a report on the study’s first phase, the researchers explained the benefits of cover crops and barriers to compost applications to farmers.
“The economics of composting along with odor issues associated with composting appear to have driven compost production into unincorporated areas outside of Boulder County, far from sources of compostable materials within Boulder County,” CSU researchers wrote in a summary of the first phase of their study on agricultural carbon sequestration methods.
They recommended farmers and local government leaders probe ways to bring small or mid-size compost production sites into Boulder County to cut down hauling expenses.
Organic materials collected for composting in Boulder County are now sent to A1 Organics in Keenesburg, and hauling them back comes with a cost. But the environmentally harmful emissions associated with transporting compost take away just 3to 5 percent of the net carbon savings from using compost, which come in the form of reduced synthetic fertilizer production, an energy-intensive process, CSU researchers have found.
The researchers estimate that 27,000 tons of compost per year could be produced from materials derived from Boulder County, which would only be enough to treat between 2,800 and 3,000 acres at an application rate of 9.3 tons of compost per acre for irrigated cropland and pastures.
If treating cropland with compost becomes more popular among Boulder County’s farmers, the demand for it will outweigh the supply, which is why researchers suggested working with regional dairies to divert solids from manure lagoons to boost the amount of material going into compost mixes.
That would be a “cost-effective, long-term method to reduce agricultural greenhouse gas emissions and sequester soil carbon,” the researchers wrote.
Cover crops contribute
Protecting soil health and therefore cutting down carbon emissions also can be accomplished through planting cover crops, which can be planted in the fall alongside a main crop or after a main crop is harvested.
“Utilizing compost and cover crops to the maximum extent possible replaces some or all of the need for synthetic fertilizers, depending upon the crop,” the CSU researchers wrote.
Dan Lisco, who farms on Boulder County open space fields south of Longmont near the intersection of U.S. 287 and Niwot Road, earlier this month had wheat and field pea seeds dropped from a plane over his fields of sorghum. The seeds are now sprouting as the sorghum is ready to harvest.
“We offered to try this seeding of a crop over the top of a crop. It will help us maintain a little more soil moisture,” Lisco said.
Sam Lounsberry: 303-473-1322, firstname.lastname@example.org and twitter.com/samlounz .