Now is the time to begin looking for ways to preserve moisture in your garden soil

Published 9:18 pm Saturday, July 22, 2017

It sure doesn’t take long for a period of near-nonstop rain to morph into to our more normal season of hot and dry in mid to late summer.

It was just a few weeks ago I took a shot at explaining why too many cloudy, rainy days was bad for pollination in vegetable gardens.

For the rest of the summer we’re apt to blame high temperature for sterilizing pollen of some plant species and a shortage of soil moisture for shortcomings of other species.

Except okra, of course. I don’t know that it gets too hot and dry for okra. Garden pest insects and fungi will wither and die before okra.

Back during the wet period the soil moisture discussion was about too much water denying oxygen to plant roots because all the pores in the soil were filled up with water instead of air.

The same soil structure and physics of soil water movement are still out there when it begins to get on the dry side. Underground, water moves downwards, upwards and crossways at every angle.  The downward movement is due to infiltration and gravity.

The upward movement is caused by plants pulling water up and out the leaves by transpiration, aka evaporation. And water moves in all directions via absorption.

This absorption is actually the pull of water away from areas with low pressure into areas with higher pressure, a way of saying from damper spots to dryer spots.

My oversimplified soil hydrology lesson aside, what can we do to help garden soil stay productive during hot, dry spells?

In my opinion, the best thing to enhance soil for vegetable gardens, flowerbeds, shrubs, etc., is to increase the organic matter content.

More organic matter translates into more air pores that let water more easily move to where it is needed.

Plus the fiber of organic matter absorbs water and holds that water in reserve.

Then the dry vs. moist deal pulls that water into the dirt itself.

True, I just recently pointed out soil organic matter is shorter lived in our climate than in cooler, drier ones.

I also know not many hobbyist gardeners are going to haul in loads of composted horse stall cleanings or well-rotted sawdust every year. And gin trash has become hard to find.

But we have our own leaves and probably the neighbors’.

And the age-old green manure crop concept still works for spring and summer vegetables and annual flowers.

I am not at all opposed to folks buying dry manure and ground bark in plastic bags for organic matter, though I don’t do it.

There are more horses than people in my area.

The other thing that’s important for soil moisture management is mulching. Mulch cuts way down on water loss through surface evaporation.

And it keeps the soil a tad cooler.

It can also be the source of future organic matter, especially for undisturbed soil.

Just add a mulch layer every couple of years and the organic matter content will steadily improve.
Terry Rector is spokesman for the Warren County Soil and Water Conservation District.