RE: greenhouse-tomatoes: Water Retention of Media

["Michael Pierce" <michael@mrhydro.com>]

greenhouse-tomatoes - an email list for growers of greenhouse tomatoes.
Sent by "Michael Pierce" <michael@mrhydro.com>.
-

Media. As far as I'm concerned commercial operations do not have many viable
choices. Not only do you have up front costs to contend with, which frankly
is not my first concern, you also have disposal issues (disposal costs) and
more importantly a media that offers a minimal impact on your growing
conditions. 

For example, many people spend countless hours measuring and monitoring
leach content, root temperature, bucket/bag moisture, etc. and grow in an
organic media. The organic media is a huge variable that will skew any of
the above mentioned tests. Further, if the organic media is not properly
composted or prepared, your have introduced a whole set of other issues from
bacterial and fungus to nematodes and fire ants. On the other hand, a grower
can use rockwool or perlite and minimize many variables in the root zone. I
realize that people use what is readily available and usually use dollar
signs as part of the decision process. However, more often than not, if you
cut costs up front, you will cut revenue in the end. 

If this concept is factored into your budget realizing that production and
revenues will be reduced, great. But if you think that you are going to get
60# per plant while feeding cow manure tea and grow in shredded news paper,
You Got Another Thing Coming 

I always find it interesting that many small commercial growers have time to
tinker with things that have long been proven to be effective or not
effective but never have time to keep the dead plant material off the floor.

I think 'ole Doug's saw dust system can work, but the irrigation side of it
will have to be addressed with a simple solution (a home sprinkler system
timer can work).

By the way, the unit you mentioned already exists. It is called WOC. Water
Holding Capacity!

Michael Pierce
M & R Hydroponic Farms


-----Original Message-----
From: owner-greenhouse-tomatoes@Lists.MsState.Edu
[mailto:owner-greenhouse-tomatoes@Lists.MsState.Edu] On Behalf Of Wayne
Fugitt
Sent: Thursday, June 10, 2004 11:56 PM
To: greenhouse-tomatoes@Lists.MsState.Edu
Subject: greenhouse-tomatoes: Water Retention of Media

greenhouse-tomatoes - an email list for growers of greenhouse tomatoes.
Sent by Wayne Fugitt <wfugitt@direcway.com>.
-

Evening Michael,

Lots  of food for thought in your message.

>I'm going to see if I can get some saw dust to see what water holding
>properties it has.

  Once I mixed some witches brew media.   I poured a measured amount of 
water into the container,
measure the amount that drained out in a short interval of 5 or 6 
minutes,  then the amount over the next 30 minutes.

There was a percent perlite, but I don't recall the amount.

I was surprised at the small amount of water retained.  I suppose if there 
was a defined system of units for retention, it unit would be defined using 
a standard material like perlite.  The granulation size and uniformity 
would have to be specified as well.   So what would we call the unit?

This may exist already.

Many experienced growers have quit gambling with media by now, have they
not?

Wayne







>  My first reaction is to ditch that stuff and go with
>perlite.
>
>As a general rule, water cycle timers and individual thermostats will not
>suffice for commercial tomato greenhouses. They are very limiting and do
not
>allow for the flexibility that is needed to manage proper environmental
>needs.
>
>BTW - flushing with non-pH corrected water is going to exacerbate your
>wilting problem because it's going to knock the pH to hell and back and
then
>your anions are going to be defibrillating with the cations.
>
>In other words, there will be a fluctuation in the eddy currents that will
>incapacitate the flux capacitor!
>
>Michael Pierce
>M & R Hydroponic Farms
>
>
>-----Original Message-----
>From: owner-greenhouse-tomatoes@Lists.MsState.Edu
>[mailto:owner-greenhouse-tomatoes@Lists.MsState.Edu] On Behalf Of Eng, Doug
>MSER:EX
>Sent: Thursday, June 10, 2004 11:59 AM
>To: 'greenhouse-tomatoes@Lists.MsState.Edu'
>Subject: RE: greenhouse-tomatoes: Want to automatically trigger irrigation
>cycles
>
>greenhouse-tomatoes - an email list for growers of greenhouse tomatoes.
>Sent by "Eng, Doug MSER:EX" <Doug.Eng@gems3.gov.bc.ca>.
>-
>
>Hello,
>
>Thank you for your feedback.  The autopot system is very interesting
however
>the
>switchover for me would be too expensive because I would need enough for
>4000 plants.
>Also, I have a system in place already. The lysimeter sounds like what I am
>after.
>
>Here is bit of info on how I am doing irrigation. I have about 4000 tomato
>plants in sawdust
>filled plastic bags.  2 per bag. The irrigation is delivered by a 115v pump
>through 2" pvc
>pipe. The pipe sizes decrease until it eventually arrives at the bag as a
>pair of .045 speggetti
>feeding tubes.  I have a pair of timers (intermatic electronic - max 4
>cycles) that cycle on/off
>the irrigation pump. At this time of year each timer is programmed for 4
>cycles ( 6 minutes = 1 feeding)
>and together they feed 8 times a day.  On a cloudy day I disable one of the
>timers to get 4 feedings.
>
>This crude setup usually works okay. I try to give enough feedings to see
>drainage on a sunny day.
>Unfortunately as the plant's needs increased, I did not increase the
>feedings.  The result was
>the leachate stopped happening and thus salt builtup in the bag.  The top 1
>foot of the plant looks
>wilted and the leaves are drying out.  In desparation, I am going around
>with a garden hose and
>manually flushing each bag with plain water in hopes of correcting this
>condition.
>
>I could have avoided all this if I had implemented something like a
>lysimeter.
>
>Doug Eng,