Simple irrigation question

[luke]

My plants have been in the garden for about 4 weeks (started from seed; inside for about 7 weeks). The majority are healthy and strong looking, with a few stragglers. For the first several weeks I watered about every three days. I have mulched on top of cardboard and newspaper.

My soil is a clay base, and I am on the way to getting it improved, but it does hold some moisture. Daytime temps are in the 80's, night temps will probably be in the 70's and up here on out, and we should soon be in the 90's with high humidity (zone 8/edge of zone 9).

I am starting to hold off on watering to about once a week in the hopes that the plants will develop a deeper root system. Should I stick to the once a week watering (as long as they look good) or stick to the watering every 3 days?

[riceke]

Ah Luke...got the same type soil here...all my ground except where I have tomatoes is hard as concrete from no rain as well. If I didn't water, hoping the roots would go deeper, I wouldn't have tomatoes because their roots can't penetrate that hardpan. Now if you have cultivated deeply and have a lot of humus in your soil it's a different story.

[luke]

Well, I've tilled as deep as I can - probably 8 inches down. I have added alot of peat, but it still needs work. To truckloads of soil mixture will help that.

I did raise my rows pretty high this year, so I would guess that the top of the rows to the pan might be around 12 to 15 inches.

[ireilly]

Beliee it or not red clover is supposed to put roots down about 5 feet deep and will bring subsoil nutrients to the surface, and break up the subsoil as much as it can.

[Worth1]

Originally Posted by ireilly

Beliee it or not red clover is supposed to put roots down about 5 feet deep and will bring subsoil nutrients to the surface, and break up the subsoil as much as it can.

I dont know about red clover but crimson clover will put about 100 pounds of nitrogen in the soil to the acre if you cut it before it puts out seeds.

Clay soil may hold nutrients but not all plants can get the nutrients from this type of soil.

Microscopically true clay soil is tiny little platelets layered one on top of the other.
from experience my red oxidized clay soil by its self does not do tomatoes well.
If I amended it with compost and sandy loam it improves the growth of the plant a 100 fold.

In doing this I only need about 9 inches of good soil the roots just spread out for their food.


Worth

[ireilly]

Originally Posted by Worth1

I dont know about red clover but crimson clover will put about 100 pounds of nitrogen in the soil to the acre if you cut it before it puts out seeds.

Clay soil may hold nutrients but not all plants can get the nutrients from this type of soil.

Microscopically true clay soil is tiny little platelets layered one on top of the other.
from experience my red oxidized clay soil by its self does not do tomatoes well.
If I amended it with compost and sandy loam it improves the growth of the plant a 100 fold.

In doing this I only need about 9 inches of good soil the roots just spread out for their food.


Worth

All too true. Clay soil is a blessing and a curse. It keeps leaching down to a minimum unlike sandy soils, but it is difficult to work and needs a lot of organic material to reduce compaction. I dug fence posts last weekend so I know this firsthand. Green manures like the clovers will provide both nitrogen as well as the nutrients pulled from the subsoil. You usually turn or till them in, unless you do no-till.

Sorry to hijack the thread, but most of this is related to your kind of soil. How often you water depends on how porous your soil is. In a manner of speaking, you may not want to replace your soil too far down as it will hold water better. Loose soils without sufficient organic material to hold water require a lot of watering and leach heavily.

Also, like Worth, I find that the clay helps with nutrients, if mixed with the other things he mentioned.

I'm a big fan of leaves, turned under. Everyone else wants to get rid of them and I pick them up. All that organic matter helps loosen the topsoil. Even barks can be used.

Compost is great stuff too.

You get enough of these organic materials and free up the topsoil and you won't have to worry too much about the subsoil, I believe. Your plants will do fine laterally, as Worth said.

YMMV

[luke]

Fighting with a clay based soil is a noble battle, obviously. I make light of all the comments because I am fighting the battle, too. Bill Clinton felt your pain, and so do I. I have not been happy with any of the results until I abandoned adding supplements by the bag and added two bucket loads recently

How about the watering issue?

[b54red]

It takes a long time and tons of organic mater to change clay soil. All my beds are on a clay hardpan and one in particular has a very high clay content in the bed itself due to me foolishly tilling a lot of the clay when I was building that bed. It took twenty years of adding organic mater for it to attain a nice loamy quality. The trouble with most organic things added to clay is that they breakdown too fast and leave the bed packed hard by the end of the season. I'm going to add about 50 bags of bark fines to my beds at the end of the season this year since they take so much longer to breakdown, I'm hoping they will keep the soil looser and slow compaction.

[Worth1]

Originally Posted by luke

Fighting with a clay based soil is a noble battle, obviously. I make light of all the comments because I am fighting the battle, too. Bill Clinton felt your pain, and so do I. I have not been happy with any of the results until I abandoned adding supplements by the bag and added two bucket loads recently

How about the watering issue?

How well drained is your soil?

Is it red oxidized or black bottom land soil?

Many people mistake the black gumbo soil for clay when it really isn't clay.

If you dig a hole and fill it with water will it hold water for over an hour like all night?

I would water before the plants show water stress and only you can figure that one out.

I would stick to about every 4 days then go to 5 days and see what happens.
The bigger the plants get the more water they will need so watering less would not be an option unless they showed lack of growth from too much water.
With your hard pan so close to the surface you really wont get a long tap root anyway.

Tomato plants get their moisture and nutrients from the lateral roots.


Worth

[Chapinz8]

Based just on my experience, I believe you should only water tomato plants when they look like they are starting to get stressed. The roots will reach for all the moisture they can find. When watered infrequently, water deeply. I believe overwatering results in tomatoes with less flavor. Your mileage may vary.

[riceke]

I have some tomatoes in pots. Yesterday in the 90+ degrees we are experiencing I notice the leaves and branches of those plants were wilting. But feeling down into the pot I felt moist soil. There are times when even though the soil is moist the plant can't absorb water fast enough to overcome it's expiration rate. It is possible if you water too much even though the plant is wilted you could actually drown the roots in too much moisture. After the somewhat cool of the evening came about the plants recovered. I guess you could relate it to heat exhaustion in humans.

[ireilly]

Everyone's situation is different, soil, climate, etc., but you need to get those wet/drying cycles or the plant won't prosper. In a heavily clay soil if you don't amend you could at least drive some rebar down and get some aeration holes opened up. That's what you do anyway when the plant basically is drowning from too much water. It's the organic material that will hold moisture and provide air voids, in general. Not too wet and not too dry - the goldlocks conditions.