Cooking Up a Recipe for Improved Soil Health

Published online: Feb 17, 2020 Articles Alexis Kienlen
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Source: Alberta Farmer Express

In some ways, soil health conferences are like recipe swaps — with attendees always on the lookout for a mix of ingredients that will produce better results.

One of those recipes presented at the sold-out Western Canada Conference on Soil Health & Grazing last month came from a Colorado potato grower who farms in high-elevation, near-desert conditions and no longer uses chemical inputs.

Brendon Rockey calls the set of practices employed by himself and his brother as “biotic” farming. And it’s proved to be a winning formula, he told the 550 people who packed a hotel conference hall.

“We were able to maintain the yield of the crop, but we managed to reduce the number of inputs to grow that crop,” said Rockey, a third-generation producer who grows table potatoes and 25 varieties of certified seed potatoes. “And we were increasing the quality of the crop at the same time. That approach has a huge economic impact for us as well.”

The family decided about 20 years ago that conventional farming was no longer paying off.

The amount — and cost — of inputs was a big part of the problem, prompting them to question their use of insecticides, herbicides, nematicides (used to kill nematode worms) and fungicides.

“We were trying to kill off our problems, but it wasn’t just that simple,” said Rockey. “We were forgetting about a lot of other factors — like beneficial insects and life that lives on the soil and in the plant. We were really forgetting about carbon capture.

“Those were things we weren’t having conversations about, and that’s where we were running into trouble.”

Fertilizer was another issue. Adding synthetic fertilizer would produce a bump in yield but then the yields would start diminishing. The problem, the Rockeys concluded, was that they were inadvertently shutting down nitrogen-fixing bacteria in the soil, hurting mycorrhizal fungi and adding more salt.

Because they irrigate, they were also concerned about water infiltration — and didn’t like what they were seeing.

“When we had poor soil structure with tight aggregates and little pore space, when we irrigated, the water did not go where it belongs,” said Rockey. “So we ended up putting more water on the soil.”

Reduced pore space also meant there was less air movement and not enough available oxygen in the soil. And at the same time, moving their irrigation rigs was difficult because they would sink deep into the soil.

All of these issues had a common denominator, the brothers concluded.

“We had to accept that we were the source of the problem,” said Rockey.

Although their south-central Colorado farm is far different than those of his audience, he said many of the lessons learned on his potato operation apply to any farm.

One is to use weeds as an indicator of what is right, and what is wrong, with the soil on their farm, he said. Weeds can be an indicator of fertility imbalances and Rockey encouraged his audience to find out more about the weeds on their land and see what they indicate about soil health.

Because water conservation is a top priority in their area (and an increasingly worrying one as levels of the aquifer they pump from continue to drop), the brothers are big on cover crops. (They can both reduce evaporation and remove excess moisture in wet years, he noted.)

The shift away from chemical inputs was a slow one, he said.

“We had to go back in and figure out how we can build the system up so we don’t need these chemicals,” he said. “That was an important part for us.”

That eventually resulted in their ‘biotic’ system, which is based on carbon cycling.

Cover crops are part of that as they help increase levels of bacteria and mycorrhizal fungi while adding nutrients and more carbon to the soil.

Initially, Rockey said they put too much emphasis on biomass on top of the soil, instead of focusing on the root systems, which is where the real action happens. Particular attention is given to the rich mix of cover crop species, which includes ones with long roots. The breakdown of the root systems adds to the soil structure and feeds the fungi in the soil.

“Bacteria and fungi break down the roots and you end up with a release of energy,” he said. “That plays an important role in soil structure.”

Having long roots opens the soil and brings oxygen down there.

The Rockeys also add compost (a fish and soybean product) and manure, but no longer use any synthetic fertilizers. They’ve also connected with a neighbour whose cows graze the cover crops and also have flowering plants to encourage higher levels of beneficial insects.

“The value of carbon is keeping it in motion,” he said. “I don’t like to see it in one place. We need that carbon coming in and coming out. Cycling is the most important part of all this, in my eyes.”

Collectively, these changes have increased carbon levels, improved soil structure (water infiltration is better and pivots are easier to move), and reduced water usage while maintaining yields, and improving crop quality.

And they’ve reduced input costs, which are about half of those of a potato-growing neighbour, Rockey said.

“We have eliminated a lot of expenses, really emphasized investing in our soil, and that’s what has allowed us to continue to do this for a long time,” he said.