Don’t waste: cow manure could become a (more) sustainable fertilizer

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A field in Bethel, VT. Photo: Liz West, Creative Commons, some rights reserved

By VALERIE PUMA

Cortland standard

If you’ve ever set foot on a dairy farm, you know that the scent of cow manure accompanies the land. Farmers face the challenges of disposing of waste every day, but a trend towards sustainable fertilization could be a modern solution.

Small farms with only a few dozen cows may have simpler solutions for manure that do not pose environmental risks. But farms with more than 200 cows face more challenges. They sometimes have to find or rent fields just to spread the manure, or store it in lagoons. If handled improperly, manure could dump excess nutrients into aquifers or other water sources.

However, heat the manure to 700 to 1,200 degrees Fahrenheit without oxygen and you can create a biochar fertilizer. The process is known as pyrolysis, which is very different from incineration – instead of producing only ash and smoke, pyrolysis produces liquid and solid residues that are rich in nutrients.

Leilah Krounbi, a PhD student in biochar research at Cornell University, grew crops with nutrient-rich manure biochar, including radishes and tomatoes. By processing biochar to enrich it with nitrogen, Krounbi’s crops have seen their plants grow up to 35% more.

Krounbi said interest in biochar stems from three interests:

* Produce energy by pyrolysis.

* Find a solution for biomass waste from forests, farms and even urban waste.

* Create alternative soil amendments to increase soil fertility.

“It seems that the idea of ​​enriching biochars with nutrients to use as alternative nutrient fertilizers came later, as people understood the chemistry of these materials better,” Krounbi said. “The pyrolysis of nutrient-rich raw materials, such as manure, appears to be the latest development. “

Fertilization with biochar could reduce the amount of manure to be disposed of on farms and protect the region’s natural resources. Manure runoff into surface water can deplete oxygen for fish and other aquatic life, Krounbi said, and nitrogen from manure could pollute groundwater and pose health and safety risks.

Test ride

But biochar doesn’t have to be made from cow manure, or just fertilizer.

In the early 2010s, Main Street Farms in Cortland partnered with Cornell University to conduct a biochar trial using wood chips, said Adrianne Traub, who worked on the farm.

“It was pretty clean energy production for us because we were using a lot of energy to heat our hydroponic greenhouse,” said Traub, now project coordinator with the USDA Local Food Promotion Program of Seven. Valleys Health Coalition. “So instead of using oil or natural gas, we were able to use it to generate heat and provide seasonal extension for growth earlier in the spring and later in the fall.”

The wood chips were released into the combustion chamber, where they burned at such a high temperature that little smoke was created.

“After the firebox, there was a fan that pushed this hot air into the greenhouse and a vent that passed through a hole in the top of the greenhouse to release excess smoke,” Traub said.

The Main Street Farms greenhouse used an early version of biochar technology that still needed adjustments, but the results during its trial farming season were notable.

“This is a viable new agricultural technology,” Traub said. “I think that with increasing efficiency and improving design over the years, it could be of great help to farmers both for heat production and for sustainable soil amendments. soil to improve soil quality. “

Environmental policy

Biochar fertilizer has been a passionate topic for Assembly Member Anna Kelles (D-Ithaca) for years.

“It is a 100% solution to increase soil carbon sequestration, increase soil quality, decrease the need for fertilization and potentially decrease the need for certain pesticides,” Kelles said on Saturday during a legislative visit to the Cortland County Farms.

Kelles grew up on a farm road in Tompkins County, then went on to study biology, environmental studies, and nutritional epidemiology. She now chairs the Assembly’s sub-committee on agricultural production and technology.

Kelles co-sponsored a bill to create a program to help farmers improve soil health and simultaneously reduce the effects of agriculture on climate change – a bill that was passed by both houses but must be reconciled. She said biochar fertilizer could be one of them.

“If you’re on a farm, you can use excess manure so you don’t have to buy extra fields to spread to the fields – instead, get a pyrolysis unit, make the biochar, and turn over.” “it in the dirt,” says Kelles.

The downside is that there is still research to be done regarding the manpower required to operate different pyrolysis units, how to integrate it into farms, and what the cost would be to individual farmers.

Centralized pyrolysis facilities would likely be more efficient than small farmers creating biochar themselves, Krounbi said. “It will also be cheaper for farmers, not forcing each farmer to invest in their own stoves, but rather to share the costs within a community.”

“I want my colleagues to understand this better and for us all to talk about it more, so that we can start exploring pilot funding, working with farms and finding ways to integrate it,” Kelles said. “The benefits are too great to ignore. “


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