Compost tea makes soil more active

Southeastern Saskatchewan farmers use enhanced biology to improve their crops through a healthy approach to dirt

Southeastern Saskatchewan farmers use enhanced biology to improve their crops through a healthy approach to dirt

Derek and Tannis Axten apply compost tea soil inoculant with a liquid kit on their 60-foot drill to fast track soil regeneration at a broad acre scale.

The couple work a 6,000-acre family farm with two-thirds of its land base in Minton, Sask., and the rest near Milestone, Sask.

They intercrop and use cover crops to increase plant diversity and maximize the number of days that living roots feed soil microbes, which has improved their soil.

However, they wanted further gains, and faster.

At a farming conference in the United States, Gabe Brown, a well-known presenter in the regenerative agriculture movement, suggested to Derek that techniques used by Elaine Ingham may help him introduce beneficial soil critters to his fields at a large scale.

Tannis then took an online course called Life In the Soils offered by Ingham and spent five days on Ingham’s research farm in northern California to learn how to identify soil critters with a microscope.

“We do a lot to protect our soils and protect the biology we have, but when we started looking at it and realized it was mostly bacteria, we realized we needed to restore the soil food web and get some of those predators and/or fungi into the soil,” Tannis said.

The goal for the compost tea inoculant is to reintroduce beneficial soil microbes that were lost after years of tillage and agronomy that wasn’t focused on soil health.

Once applied, the soil organisms from their homemade inoculant habitat increase root exudates caused by the highly diverse rotation, which kicks into high gear nutrient cycling in their fields.

Manure for their compost is sourced from their neighbour’s feedlot, which helps to reduce the cost associated with his manure bill come corral cleaning time.

“He’s glad to have us take away the manure and we’re glad to use it,” Tannis said.

 

The compost that the Axtens use in their fertility program is based on local manure mixed with straw, wood chips, grain screenings and other organic material from the farm. Generally it is turned five times. | Axten Farm photo

Compost rows are started when they make long rows of manure with a manure spreader.

Straw, screenings from their grain cleaner or whatever is lying around is added to the manure windrow to reach an appropriate ratio in the compost of 25 to 30 carbon to one nitrogen.

“One thing we struggle to get around here is the woody component,” Tannis said.

“We don’t have any trees here so that’s one thing we usually buy is wood chips or wood shavings to add for a high carbon source.”

They then use a compost turner to mix up the manure/carbon source windrow.

“I go out every day to check the temperature,” she said.

“We like it to get over 131 F for at least three days in the very centre, but not over 160 F,” Tannis said.

“Once it’s hot enough for long enough, we turn it so that the outside can get into the outside to heat and the middle can get to the outside and cool off a bit.”

The piles are turned at least five times.

Once a pile is finished it returns to ambient temperature and is ready to use.

Thousands of tonnes of compost have been produced and added to the Axtens’ fields, but it’s tough to distribute across all of their acres.

Instead, Tannis identifies the compost with the strongest and most diverse population of beneficial micro-organisms and then extracts them into a compost tea.

“Making extract with the tea is a good way to take a smaller amount of compost and get the biology out over a lot of acres,” Tannis said.

“We have a compost tea brewer. It’s a 500 gallon cone tank we fill with water and put in baskets of compost in a tea bag. The water bubbles with a big air pump and it basically is extracting the organisms off the compost and into the water.”

How much compost is needed to make a potent tea depends on the quality of the compost and the diversity of its micro-organism population. However, she said a 500 gallon brewer requires approximately 15 pounds of compost.

“I wasn’t 100 percent happy with mine, so I used more than that,” she said.

“I just changed the compost in the tea bag so that I had more organisms to extract off.”

She watches the compost tea closely with a microscope to monitor its micro-organism composition.

Food such as kelp or fish hydrolysate are added to feed the micros in the tea just before Derek takes the solution to the field to apply in furrow with the liquid kit on his drill.

The food supplements help sustain the micro-organisms until they move onto the crop’s root exodies that their newly planted crops will provide.

“In a tea you add those foods and brew it for at least 24 hours, but we didn’t want to because you really have to keep it aerated then because when the organisms are really growing they really require oxygen,” Tannis said.

“So we just add it right before it went to the field.”

The Axtens farm in southeastern Saskatchewan, near Minton and Milestone, and have experimented with intercropping, including flax and chickpeas as mix in their fields. | Axten Farm photo

It is too early to tell how the compost tea affects yields on the Axten farm because last year was their first field scale use of the tea inoculant and it was too dry to compare to previous years.

“I have noticed more diversity (of soil micro-organisms),” she said.

“I can’t say 100 percent that it’s because we put extract down because we work hard with the diversity in our crops and our cover crops to create a good environment.”

Derek said growers have to be capable of identifying soil microbial organisms before jumping in to applying a compost tea inoculant.

“You can multiply up some stuff you probably don’t want to multiply,” he said.

“I don’t know if I’d recommend doing this because I’ve had people call me saying, ‘I have this manure pile and I made tea.’ That can be bad because there is all sorts of things like E. coli that can be there.”

Tannis said they use thermal compost because there is less chance they will spread something on their field that they don’t intend to put there.

“There are a lot of different ways to compost, but that’s why I like the thermal compost because we know we are getting rid of, not just pathogens but for us it’s the weed seeds,” she said.

“We don’t want to be spreading those in our fields.”

For growers who don’t want to learn how to identify soil micro-organisms with a microscope, Derek said a phospholipid fatty acids (PLFA) soil test will provide the same information, and it’s a good way for growers to gain a understanding of their soil’s microbial environment.

“There are established ranges and guidelines of where you should be to be in a good functioning soil,” he said.

“That is all pre-existing. We are just trying to get ourselves back up to where it was before we stuck a plow in the ground 100 years ago.”

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