Change soil every year?
 

We've had a very late and wet spring and to work around some of this I now have more than 200 tomatoes planted in 25 gallon cattle feed containers. They are much tougher than black nursery containers, plus they don't have holes punched in the bottom that let's all the water drain out. We drilled holes aboutt 4 inches up to serve as small reservoirs.

Two hundred containers x 25 gallons each is theoretically 5,000 gallons of "soil." I just a mix of rich topsoil and cotton gin trash, which is great organic matter that is like compost that we have in abundance here.

I'm aware of the reasons to not plant tomatoes in the same spot each year, but I also know that Earth-tainers and container growing is very popular, and i doubt that all people can afford to replenish their containers with fresh compost or soil mix every year.

Is there an effective way to treat the soil mix at the end of the year that renders it safe and harmless for re-use the next year? What is the best way to deal with the problem of not growing in the same dirt or soil-mix every year?

Thanks in advance!
Don

Don,
Here is a link about my raised bed I had at work which was no till and was amended at the end of each growing season with horse manure after the plants were removed. Used old bricks taken
from an adjacent building that was torn down to make the bed. As the bricks were stacked one on top of another offset from the brick below provided stability and adequate drainage from rain.
Ami
[url]http://www.tomatoville.com/showthread.php?t=25589&highlight=surrogate[/url]

Hi Don! I’m planning to heat bake my container soil by enclosing in clear heavy-duty plastic garbage bags and leaving out in the sun for July and August, when it’s too hot for tomatoes.
I’m using a mostly soilless 5-1-1 style mix but the type of soil doesn’t matter from what I understand. My plans are based on the experiences of Marsha, Barb_fl and others here in TV.
- Joyce

The most important thing you can do for container soil is to remove all of the tops and leaves at the end of season. Unless you have soilborne trouble with nematodes or fusarium, the other disease overwinters on plant material, not if you remove it. I dig out some of the bigger roots as well. Then make sure it is kept moist enough for worms to thrive and eat up the small roots during the off season.

For an organic/garden soil type mix you need to replace 1/3 of the material with fresh compost every year.
I really regret my decision to change out my container mix after 5-6 years, because of pests overwintering in the greenhouse. It didn't really change the pest situation, but the mix which got better and gave better yields every year had to be replaced with more peat in the mix than before, and I am still struggling to get it back to the point that I started from.

IMO unless you have soil borne disease you are better off to keep grooming the mix that you have and it will reward you just like any ground that you plowed good things into.

Hey Don,
I agree with "bower" above...I grow all my peppers in the same feed tubs you're using. I'm heading into year 5 with the same mix...I just keep amending it with compost, coffee grounds, etc....

Wow that is news to me. In general, I wouldn't re-use the soil used for tomatoes... but I am going to use the remaining soil I still have in one of my containers and will sow some lettuce / corn salad in it.

What is the culprit? When renders the soil unfit to use year after year? Fungus, bacteria, bugs, nematodes? Couldn't the soil be treated for this? We all know that gardeners use the same place in the back yard or at the farm over and over with no significant problems. A family here used the same garden spot at their old family farm for over 100 years and they never mentioned having to alternate it with other ground. I know a lot of people like to use old half whiskey barrels in patio gardens and I would be surprised if they have discard the soil and add new soil each year. With limited space, another issue for them would be where to keep putting the old soil mix, unless it might could be alternated every other year.

I hope there is some way to treat the soil mix because I expect to have 250 twenty-five gallon container grown tomatoes this year and if this works I'd like to double it to 500 next year. It would be a significant investment of time and money to completely replace the soil in all of them every year. Also, what might be practical and work well on a small scale will probably require too much labor to be a practical solution on a large scale.

Any suggestions will be appreciated. This best I can think of is to treat each container with fungicide at the end of the year when the plants are pulled, but I doubt that would be enough to treat all the other possible issues.

Thanks in advance.
Don

Fungus gnats will be a problem only if the containers don't drain well. They have only been a problem for me indoors, fwiw, they don't thrive where the air circulation is good. So you may find the reservoir in the bottom of your containers is a problem, if so the answer is to drain them better, and treat with BTi, that is Mosquito Dunks, Mosquito Bits or similar product which kills the gnat in larval stage. I just soak a dunk in a gallon of water and pour that on. I believe you can keep soaking it until used up. You can also crumble the bits or dunks onto the surface or lightly mixed in, and it will continue to release whenever you water. The BT israelensis products are specific to larvae of flies and don't harm any beneficials (unless they are flies!).



People who change out container mix regularly are mainly using a soil-less mix and liquid ferts. The rationale I believe is that the fibrous particles in the mix break down and no longer give the desired texture. An organic mix, well you have to keep adding organic matter, make sure it is well aerated and well drained enough, and being outdoors it should have no more pests or soil problems than any other soil/plants in the area.


Worth posted some interesting discussion of a method without drainage in the container that seems to work in the dry and hot climate of where he's living. There is a drain installed so in case of heavy rain flooding the container, it can be siphoned off. This could be a lot of work though if it rains often. I also suspect that waterlogging encourages rots and unhelpful microbes instead of the good ones.



@Goodloe, what are you doing with coffee grounds? Looking for ways to tweak my mix. :)

Plants in pots have a finite amount of soil to live in. They change the soil. They remove minerals, trace elements, and nutrients such as nitrogen, phosphorous, and potassium. Also, watering a pot, the water picks up water-soluble things (fertilizer, minerals, etc) and over time flushes these out the bottom of the pot. Furthermore, soil in a pot breaks down into a finer and finer texture, which changes its structure making it more dense. This is why you add compost to the soil in buckets every year. (Soil out in the world gets that sort of addition (leaves, dead plant matter, etc) naturally.) Compost adds new nutrients and better structure to the soil. Take some out to make room for the new compost.

[B][SIZE=4][FONT=Garamond]I use fresh mix every year (Pro-Mix HP)... mainly to avoid the inevitable salt build-up from water-soluble fertilizers. Also, as was mentioned, the mix becomes denser after a full season of use. [/FONT][/SIZE][/B]

If we're talking about the red plastic protein tubs I use you should at least amend the soil. Either dump all the old soil onto a tarp and add new compost and organic matter, plus enough sand or pea gravel to assist with drainage. Or just use the old soil for layering in your compost pile and use fresh mix.

If you have problems with disease or pest dumping the soil on a hard flat surface, spreading it thin, and giving it a week of sunlight to kill some of the bad microorganisms will help. This is a good idea anyway because it helps to prevent sour pockets developing in the contained soil.

I think 4 inches is a pretty generous reservoir. I go with a little over one and still worry about steamimg the roots in hotter weather although depending on climate that may not be an issue for you.

I've been using the same mix for several years in earthtainers. When I pull out the old plants by the roots, some volume is lost, some is also lost to compression over time, and some maybe even washes out in heavy rains. Every year I replace the volume lost (10% or less I estimate) with a mix that is heavy on pink bark fines and has some perlite in it. Both are good for keeping mix from getting too heavy/dense.

Should I ever get a serious disease issue, I'll consider a complete new soil, depending on whether it is a soil borne disease. I do not notice any decrease in vigor or production using this method.