Keyline plowing results: 522,720 worms for $280

Categories: On The Farm

Even though originally, we were trying to address soil compaction, active carbon was the key characteristic for us to watch. It responds quickly to management changes, because active carbon is tied to changes in biological activity, meaning that if there is much more food available for soil microbes, there would be more active carbon present. If changes were afoot, we should see it in active carbon measurements. 

Out of the hundreds of samples, and readings, and measurements, we saw no changes. No changes to the very responsive indicator, active carbon, and no changes in other soil or forage characteristics, such as soil organic matter or bulk density, or forage NDF. What this trial told us is: keyline plowing didn’t change soil or forage quality on these four farms over the 2 ½ years we were monitoring pastures.  There may be additional conclusions to draw, but first let’s talk with the farmers.

The farmers told us some more. They were pretty frustrated by what keyline plowing did- three of the four said it made those paddocks very bumpy to walk across. For the ones that hayed or mowed pastures in addition to grazing them, they said that the tractor ride was very uncomfortable. The shanks of the plow pulled up stones, and that was really irritating. Mark added a roller behind the plow to smooth the surface, but the slices still made the pastures a pain in the tush.

A couple of the farmers were dealing with moisture issues in their pastures. In one case, the farmer noted that it seemed like the plow lines were moving water away from wet spots, and that was appreciated. In another case, though, the farmer said it seemed like the plowing dried the pasture out more rapidly, and the plants looked like they were drought stressed.

There was another group we still wanted to hear from. Earthworms are pretty good indicators of soil quality, and we were counting on them to shed more light on the situation.

Epigeic, endogeic, and anecic. Useful for naming worms and for playing Scrabble. - See more at:!prettyPhoto

There are three main types of worms: Endogeic, epigeic, and anecic. The endogeic and the epigeic stay closer to the surface. The anecic, though, burrow deep into the ground. Those deep burrows can translate into lost nutrients, when the materials the anecic worms have transported are washed deep into the soil profile, sometimes reaching the groundwater. The worm counts told a story that we didn’t find anywhere else. We found higher numbers of endogeic and epigeic worms in the keyline plowed pastures than in the control. The numbers of anecic worms were not that different though. 


Worms per square foot, under keyline plowing and a neighboring paddock that was not plowed. There were more epigeic and endogeic worms in the plowed paddock, translating to about 522,720 more worms per acre. 

There was an average of 27 endogeic and epigeic worms per square foot in the keyline plowed pastures, versus the 15 per square foot in the control. An acre has 43,560 square feet. With an extra 12 worms per square foot, there were 522,720 more worms per acre in the keyline-plowed pastures. The presence of more worms suggests faster turnover of nutrients and better aeration.

The cost of keyline plowing was about $280/acre, or about 1867 worms for every dollar. Since we didn’t find any increase in forage, forage quality or other soil quality indicators, we’re left wondering if opening up the soil to more worms is worth it. More worms has usually been considered a good thing, and at almost 20 worms for a penny, those worms seem like a great price. 

It turns out that worms might not be the best things for climate change, though. The process of churning and digesting organic matter seems to increase the release of greenhouse gases and doesn’t seem to increase the amount of carbon being stored in the soil.

With the verdict on worms not 100% positive (sorry, worms, we really do love you!), we’re still asking, what will we see in the long run? We haven’t seen the 8” of topsoil that was touted, with no increase in organic matter or active carbon. Since we burned a good bit of diesel for those worms, we definitely didn’t do the environment any favors.

Is it that keyline plowing is more suited for drier climates, where water is a limiting factor in production? We’re still working on that answer, and we’ll get back to you. Keyline plowing has been out there for decades, though, so if you have any evidence or data, please share it!

Until then, it’s hot out. Let’s dig up some worms and go fishing.

by Rachel Gilker / via OnPasture

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