Walking subsoiler

[wild millers]

I know that I have found a few threads on the forum talking about subsoiling, though they seemed older, I would love to hear any updated feedback on test results or findings. I bring this up because I wanted to throw this out to the community here that we have converted an old walking potato digger into a walking subsoiler and next sunday July 7th we will have two teams going. One team on the walking plow set as deep as it will run, followed by another team pulling the subsoiler. If anyone is free and interested to see how it goes you would be welcome to come by. We have never run this before, nor found anyone with any experience running it so it may take some adjustment and futzing. We will be covering a garden plot of approx. 6600 square feet. This is in our market garden with some of our easiest to work soils, free of any stones larger than a baseball. Our intention here is to break through the hardpan that came with this field that we have been working now for 5 years. Through this we hope to make the overall soil moisture more available for our un-irrigated vegetable crops by allowing their roots to penetrate deeper into the soils water reserves. We’ll be starting just after lunch and I expect putting in 2 or 3 hours. Anyone that comes would be welcome to stay for a potluck supper after chores. Of course this is all weather depending, so I will post an update late next week. Cheers -Joel

[dominiquer60]

I am looking forward to hearing how this goes, short term and in the long term.

I have no experience sub-soiling, but I have some serious compaction in one field that I have been working the last couple of weeks.

Last year at the Nordell’s Columbus Day Farm Tour I asked Eric about his zone ripper (sorry I don’t remember what he called it) that I have seen pictured in SFJ, I was interested in seeing it and using something like it for the water reason and to loosen the soil for crops like carrots. He had sold it because he no longer used it, because the rows where it was used actually dry out verses no/min till methods that rely on capillary action to keep moisture near the surface, but with a soil or plant mulch to keep water from escaping at a high rate.

I am going to try to address compacted soils with cover crop roots when space and time allow for such species.

I tried a little experiment last week with the opposite idea, drying a field out. Sam wanted to disc it so that it would start to dry, I wanted to leave it so that the natural cracks and fissures dry it without another pass with the tractor. I scratched a tiny patch of this 5 acre field with a rake to break the crust and to create a soil mulch and mostly due to lack of time we waited a few days to work it with the tractor. The field dried out nicely on its own to a very nice workable moisture content (it was like pudding before), and that little patch that I scratched just for kicks certainly held more moisture under the dry layer on top.

What I am starting to realize is that it is important to address compaction, but the deeper you dig the less moisture you retain at the surface. It is all a balancing act. Tim Harrigan recommended to me in another thread to try the sub-soiling in a swath or two to see if it actually helps or not, rather than doing it all and wondering later if it actually helped or not without a control for comparison. We never were able to find a sub-soiler to borrow, but I am leaning toward legume or radish roots to break up compaction these days.

Happy Plowing!

[wild millers]

Erika, thanks for your thoughts.
Your questions are also my own for the long term effects of this operation. This particular field in our market gardens has been participating in a study on soil health through Bianca Moebius-Clune and her team at the Cornell University soil health lab, for the past 2 years. The study runs a 4 year course and is being replicated on about 10 farms in NH, it is being tested on crop ground, pastures, and hay field alike. Soil health testing means she is testing for physical and biological activity in the soil as well as aggregate stability and depth/hardness of hard pan. As opposed to just the chemical readout of available nutrients. More can be found out about this here.. http://soilhealth.cals.cornell.edu/index.htm

This fit in with our goals of making our market gardens drought proof since we do not irrigate the field crops and would like to build our resiliency to erratic weather patterns. Anyway, we divide this field into four sections to help facilitate our cover crop and cash crop rotations. We will be attempting to subsoil the far left plot in the photo this time around and hopefully the near left as well soon after. We consider this subsoiling to be a one time effort as once the pan is ripped we hope it will stay broken under our low till horse powered operations. The two plots on the right in the photo are both also dealing with the hard pan issues, but they both have a few spots where the soil is a bit thin and bony. Stoney, and we couldn’t subsoil very easily. In these plots we are focusing on tap rooted cover crops..tillage radishes, and sudex. The near right plot in the photo is a solid stand of tillage radishes last fall. The tillage radishes were part of our no-till onion experiment that we will be putting together a small photo essay about. Possibly contributing to to a multiple farm collaboration about tillage radishes in Anne and Eric’s CQ column in the SFJ in the near future.
Anyway the jist of all of this is that two plots will be tap rooted or bio-drilled using cover crops to break the pan, and two will be mechanically subsoiled by live horse power for a directly side by side look at results. The soil health experiment will continue for this season and next and we will be looking forward to what we find.
Finally to be clear I should say that the plots we will be subsoiling this coming week will be on their way into a summer bare fallow period before being cover cropped in august for spring veggie planting. I wanted to fit this into a slot in our rotations that didn’t have a cash crop following it for the reasons Erika stated about the evaporation of soil moisture to the depth its been worked. -Joel

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[dominiquer60]

Now I am really looking forward to knowing how it all works out 🙂

[bendube]

I’m to understand that one issue in sub-soiling in New England is soil moisture. If you’re trying to really bust up hardpan, the soil should be dry so that the chisel shatters the hardpan. If its too wet, the tool will cause smearing instead. This year especially, getting the subsoil dry enough could be very difficult. On our fairly wet bottomland soils, its a pretty rare year that we don’t have a lot of subsoil moisture. Also, if the pan is usually wet, then this means the biodrilling would work more easily, roots would penetrate easily.

Cool project, excited to see the results.

[wild millers]

Well, we had at it today. Taking breaks every now and then we were able to work around the 90 plus degree heat, we started around 11, took a break for the afternoon then started again at 6 or so and finished up around 7:30. I say finishing up, but we had to leave the last few furrows un-finished because a mighty thunderstorm blew in. Overall I think it was a great success. We were running the subsoiler at a consistent 15-16 inches deep, sometimes a little more sometimes less. The three horse hitch was definitely necessary. They were able to pull it, and quite readily they did so, though they were working for it.
I was driving the young team out front with the plow and some friends pitched in to drive the three abreast with the subsoiler behind me. A few observations made…I was pleased with the vertical suction of the subsoiler, though I wish that I had been able to set the point at a steeper angle so that the beam would have been able to run a but more parallel to the ground. I set it at this angle by taking measurements off of a yeomans plow shank, and if we set it any steeper it would interfere with the potato plow, when we wanted to bolt it back on, which will bolt back on with two bolts. As it was, we had to flip the vertical clevis upside down to gain enough of a hitch angle to get the subsoiler to bite at this depth. That said though, we were able to make it work, so I’m not sure I have any complaints about it. The beam just looks a bit funny. For the most part when they laid into a stone, it would tend to pop it up onto the surface, though they did hit at least 2 that stopped them dead. The team stopped quickly though and it wasn’t much work to lift the shank out and let the team re-set it again past the stone. For those observant enough, you may have already recognized what the point for the subsoiler is made of. Take a look again and you will see the spike of a pick ax, cut off at the head and welded on the bottom on the beam! I’m debating at this point whether we should try to finish the field as we started or leave the last little bit as a final variable for the comparison of the sub-soiled, non-subsoiled, and bio-drilled gardens. I think we may do this whole plot again next year to finish the field for good. As it was we were running the subsoiler every 12″ or so across the field in each furrow bottom, so we ended up with pretty good coverage I think, but again, if we do it next season as well we would probably break it all up for good!

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[wild millers]

bendube, thanks for the thoughts. With those concerns in mind when we went to the field today I was curious to see what we would find. We aren’t on what you would call bottomland in this garden, though about half of it is lower than the other and it doesn’t drain very well right now. When the subsoiler had past through, we went back and excavated a little to see what it looked like and found the hard pan to be moist, though not soggy and while I wouldn’t say that we “shattered it” we also didn’t “smear it” it was pretty cleanly cut through with a few chunks of compacted hard pan broken up and pushed up near to the bottom of the furrow.
A few more pictures…

also you will notice that with three abreast, one horse was walking on the plowed ground, one in the furrow, and one on the land. I was able to justify this because for one it made the subsoiler track straight in the furrow behind the middle horse, and the other reason is because I was using our little hillside plow. At each headland we were swinging it around and alternating from left handed to right handed plowing. This meant that at each headland turnaround the outside horses swapped positions from land to plowed ground, thus not leaving one horse walking on the plowed ground all afternoon.

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[Eli]

It would be interesting to see a cross section. We did this years ago with several different tractor tillage tool. A ripper worked the best a ripper is like a sub spoiler with a horizontal bar to shatter the hard pan. Eli

[bendube]

Nice job putting that tool together! Looks like everybody had a good time.

Thanks for sharing this work and please let us know how this field plays out next year.

[Author]

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