[Market-farming] Hard soil inside the High tunnels

Bill Shoemaker wshoemak at inil.com
Tue Nov 23 15:20:22 EST 2004

I think it might be possible that the tunnel is part of the problem re: hard
soil in Hi-Tunnels. We've experienced the same thing in our tunnel at the
research center. I think at least two things are contributing to the
problem. First, lack of moisture from Fall til Spring means the ground
thoroughly dries out, especially with the warm temps that often come during
the day inside the tunnels. In our area we can't provide moisture because of
the constant freezing conditions, which would break up the pipelines and
water control systems. Second, we use a tiller to prepare the soil, which,
by the way, is a very black silt loam soil, not usually a soil with
friability problems. Tillers break up soil too much, leading to collapse of
the soil structure, unless roughage (compost, green manures, aged manure,
other organic matter) is added. So I've come to the conclusion that soil
management, and especially moisture management, is a critical issue in
tunnels. I'd almost like to see tunnels that can be opened up in the off
season to allow natural sources of moisture to enter the tunnel. We lift the
roll-up sides all the way for the Winter.

By the way, the sand discussed earlier is called mason's sand around here.
It's also called sharp sand because it has sharp corners, unlike beach sand,
which is highly eroded and very round. I used to be a concrete finisher and
when it was explained to me they said the sharp edges work better in mortar
and concrete because the cement "grabs" it better. In soil it likewise works
better structurally.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center

>It's unlikely the hoop house is the reason for poor soil condition.  What
is the soil like growing *outside* the hoophouse?  Have you had the soil
structure tested? Is it caliche?  It may be that it's just not enough
compost, or that it will take much longer and much more mixing with the
right amount of moisture present. Not all soil can be amended enough to make
good growing medium.  Due to its structure, some soil has been compacted too
much before trying to compost and grow in it.
>paul at largocreekfarms.com
>*********** REPLY SEPARATOR  ***********
>On 11/23/2004 at 9:30 AM robert schuler wrote:
>>Hoop house growers around here  plant on plastic covered raised beds
>>with drip. There is little compaction after the plastic is in place.
>>Sunny Meadow Farm
>>Bridgeton, NJ.
>>Marlin Burkholder wrote:
>>>      While this "High Tunnels" thread is going strong, I have yet
>>>      another question I would like to insert.  In 2000 I built my
>>>      first permanent hoophouse.  I chose the site primarily
>>>      because of it's proximity to the house and water supply and
>>>      because it fit well into the building landscape.  The soil
>>>      on the site was of high sticky clay content, not my best
>>>      soil.  I reasoned that because of the high cation exchange
>>>      content of dominantly clay soils, I would eventually be able
>>>      to build it into a highly productive soil by the diligent
>>>      application of compost. It is now four years later, and
>>>      despite what I thought was a valiant attempt to improve the
>>>      soil by yearly deep digging in of compost and earthworm
>>>      castings, I am still a little underwhelmed by the quality of
>>>      the soil inside that hoophouse.  Rather than acquiring a
>>>      soft crumbly structuture, the soil has gravitated more
>>>      towards an aggregate of hard gravel sized clay lumps mixed
>>>      with a dark brown dusty, almost gritty residue which I
>>>      presume to be the remains of the compost applications.
>>>      When I began to dig up the beds this fall,  I found the soil
>>>      to be tight, and it dug up as head sized mottled red and
>>>      brown clods that were difficult to break apart.  I ended up
>>>      loading up most of these clods into a wheelbarrow and
>>>      dumping them outside the hoophouse.   There they will be
>>>      exposed to freezing temperatures this winter which I hope
>>>      will soften them up.  I then replaced this soil with an
>>>      equal volumne (about 15 wheelbarrow loads in 220 square
>>>      feet) of fresh compost and worked it in once again.  Despite
>>>      all my efforts, I still feel like I am working with dirty
>>>      gravel instead of real soil. Could it be that the lack of
>>>      normal freezing and thawing of the soil inside the hoophouse
>>>      during the winter, and the baking effect of summer's heat be
>>>      the cause of the hard soil?  I have had some kind of mulch
>>>      (old hay or cardboard) on the soil during the summer, and
>>>      usually a pretty good gound cover of salad greens during
>>>      much of the winter.  I walk on the beds as little as
>>>      possible.   I wonder if this isn't a common problem for
>>>      hoophouse growers. Marlin BurkholderVirginia Shenandoah
>>>      Valley
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