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Editorial: Still lots to know about mechanisms of soil health

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The maintenance of soil health has come into much greater prominence in the past five to 10 years. That’s an important step — our soils are the basis of civilization and those that have not understood that have had civilizations collapse. Check out the Nile River delta today.

We’re a long way from the lack of understanding that doomed ancient civilizations. We understand erosion and can test organic matter. We know declining soil health means lower future potential in those soils.

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But we still have a lot to learn. It will be years — if ever — until we have a completely solid set of best management practices for soils. That’s OK as long as we keep the focus on improving soils.

One of the interesting things about growing crops or raising animals is that you are dealing with biological systems. That means challenges and no year is ever the same, which keeps farming interesting. It also creates great frustration.

We’re only now really understanding the complexity of soil and how challenging it is to build, maintain and manage organic matter and other soil health factors.

Take a look at a couple of the presentations at the recent SouthWest Agricultural Conference (SWAC).

Adam Gillespie, of the University of Guelph and OMAFRA’s Anne Verhallen talked about the connection between microbes and soil health. There’s more research that says that more than 50 per cent of soil organic matter is formed through microbial pathways. What does that mean? And how do farmers manage microbes? There’s a farming couple in Saskatchewan, Derek and Tannis Axten, who monitor and manage microbes on their farm. They say they farm with a microscope.

What about root exudates? Root biomass has a significant effect on soil organic matter formation.

Then there’s the whole debate over cover crops. There’s no doubt they perform numerous services on farms — sequestering carbon, increasing organic matter, holding soil over the winter, keeping nutrients in place. But there’s still a lot to learn about what the best route is in cover crops. There’s massive on-farm experimentation going on, which is excellent, but I expect the end result will be: it depends.

Humberto Bianco of the University of Nebraska-Lincoln, also spoke at SWAC on whether farmers should be using single or multi-species cover crops. There have been some wildly complex mixes used out there, with the thought being that diverse species better mimic nature.

However, Bianco argues that, so far, the research says that limiting cover crop diversity will mean more biomass, a better route to improvement in compacted soils and better weed suppression.

He says that if cover crops only exist for several months of the year (they are usually planted in the late summer or fall and terminated in the spring before the next annual crop), then a diverse cover crop mix might not make as much sense.

There’s still a lot to learn.

Then there’s the economics of soil health improvement. Yes, there’s little argument that soil health is important, but if you have to pay for a cover crop, or more expensive or diverse equipment (such as a strip-till unit), it’s difficult to make that pay year over year — because the bills have to be paid each year.

I’ve argued before that investing in healthier soils needs to be amortized (including by a lender) like a piece of equipment or a farm building — it’s an investment in future efficiency and it might take time for it to cash flow positively, but the investment can make sense over time.

We’re still trying to figure out how to value soil organic matter. Should it factor into the price of a farm? Judging by the steadily high prices for farm land, I’m guessing it doesn’t. I haven’t heard of anyone saying that the soil organic matter is five per cent, so I’m going to pay more. But I know that people will say they’ll pay more for a farm with good soil (or more accurately I hear consternation about how much people paid for a farm with poor soils).

In most cases that local reputation of a farm for good soil is based on organic matter (as well as soil type — also
influenced by organic matter — and long-term management).

And there’s the challenge that yields keep going up, even though our soil organic matter continues to decline. That can’t continue forever.

The drive to better understand soil health is critical if North America hopes to continue the agriculture productivity needed to feed other parts of the world.

We still have more to learn yet.

About the author

Editor

John Greig

John Greig has spent his career in agriculture journalism and communications. He lives on a farm near Ailsa Craig, Ontario. Contact John at [email protected] or follow him on Twitter @jgreig

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