Tips for improving organic soils

Soil scientist Jill Clapperton met with farmers at the SaskOrganic annual meeting in Regina March 31. Photo: Laura Rance

By Laura Rance
OrganicBiz editor

Fababeans are gaining ground in both organic and conventional cropping rotations because they are a good source of nitrogen for the soil and less susceptible to diseases that affect some of the other pulse crops.

But soil scientist and consultant Jill Clapperton said farmers need to be ready for the weedy hangover that follows.

“What I’ve learned is …fababeans release every weed seed that has ever been in my soil the next year,” Clapperton said in a recent interview.

Organic farmers who don’t use herbicides need to consider growing highly competitive cereals the following year, and using a high seeding rate.

“And if I’m an organic farmer, I want to be sure my Pheonix harrow is in there taking all those little plants up,” she said.

Farmers might also consider following fababeans with a warm season crop or “something I can grow later in the year so I can get all those red root pigweeds and all the lambsquarters that are going to come up.”

When you are standing on your ground, you are standing on a huge city. Your soil is alive. – Jill Clapperton

Less disease

Anecdotally, organic farmers are experiencing lower rates of fusarium infections and other diseases on their farms.

Respondents to a recent poll of research priorities for organic growers didn’t cite diseases as a top concern.

A recent Western Producer article quoted multiple industry sources who had observed the phenomenon.

Clapperton said she has no definitive answers as to why, but suspects organic producers follow more diverse crop rotations. They also use more tillage which reduces the amount of diseased residue that might be a source of new infection.

As well, they don’t use fungicides, which in a roundabout way, may reduce their susceptibility to fungal attacks.

Spraying a fungicide kills the target fungi, but it also kills all the fungi in the soil, some of which is healthy. It also kills off all the soil “predators” which feed off fungi, she noted.

By maintaining a high level of biological activity in the soil, disease-causing fungi are less likely to take over.

Focus on micronutrients

Organic farmers need to add elemental sulphur to their fields every year.

“It’s really important that you buy elemental sulphur that is finely ground so it has a lot of surface area,” she said. “Put some on every year because it takes about a year for the population of microbes to build up that break it down. so if you don’t feed, them every year then the population goes down.

Clapperton said that’s “really important” to crop farmers because sulphur is critical for wheat for bread quality. The other thing is that sulphur is absolutely critical for plant defence so if I’m going to have fight diseases naturally, I need to make sure our sulphur is up.

Five steps to healthier soil

Clapperton says cutting back on tillage is the number one step organic farmers can take towards building healthier soils.

“Am I ever going to get an organic farmer out of tillage, no. I know that,” she said. “Because they are going to have perennial weeds and they are going to choose not to spray it.”

But she said some of the new tillage tools that are available offer new options that cause less disturbance.

“If you are going to do tillage, then I don’t want to see a lot of disturbance,” she said.

Tillage operations disrupt the microbiological ecosystem beneath the surface, which forces the plants and insects to focus on recovery rather than performing the functions they normally provide.

“When you are standing on your ground, you are standing on a huge city,” she said. “Your soil is alive.”

Farmers can minimize that damage too by timing tillage differently. They do less damage if tillage operations are carried out in the late fall.

Less tillage also fosters a healthy predator-prey relationship beneath the surface, which is an important driver for nutrient recycling.

Mulches and cover crops, which are commonly used as sources of fertility, can serve a multi-faceted role on organic farms. For example, sweet clover is a good herbicide, she said.

Companion planting and relay cropping is another tool that helps build soil quality and structure, she said. So does integrating livestock into the cropping system.

How do you know?

Farmers with healthy soils have fewer pests, less weeds and better crops, but how do you know your soil is healthy?

One hint is to dig a shovelful of dirt and turn it over to observe how much it has by way of earthworms and other insects.

“A handful of healthy soil will be crawling with living things,”

She recommends picking 10 to 12 sites and marking them with GPS.

“You can pick places in your field and do a baseline.,” she said. “Count the number of earthworms that are in there. Know where those places are in your GPS and every two years come back.”

Water infiltration rates are another measure.

“Look at your ponding. Are you ponding up? If it’s not ponding anymore, that’s an excellent indicator that you have better infiltration,” she said.

Farmers can buy or make their own infiltrometre to measure how quickly water is absorbed by the soil.

Or you can take a handful of soil and place it in water to observe the amount of bubbles it emits and how well it holds together under water. If it is releasing lots of oxygen, that’s a sign of biological activity. If it disintegrates into muck right away, biological structure is lacking.