For Release November 3, 1998

Wet Soils Require Extra Care

AGRI-VIEWS
by Chuck Otte, County Extension Agent

I guess there’s no way to deny it, this is going to be a wet fall! Rainy conditions make for wet soils. Wet soils can create lots of problems and situations of their own, some good but many of them bad. If you have fall work that you wanted to do in your yard, garden or field, precautions need to be taken or you will have problems that will haunt you for months or years to come!

What happens when soils get wet? For starters they get muddy (duh!) and that’s where the problems start. Ideally soils are made up of clay, mineral and organic particles in equal proportion to voids, or spaces, between these particles. When the soils get wet, from rainfall or irrigation, these voids or spaces fill up with water. If there is a lot of rainfall all the air will be replaced with water. This is not good. Under conditions known as field saturation, the voids should be 50% water and 50% air. When soils become super saturated through constant rainfall or standing water all the air is displaced with water. Without air in the soil, plant roots start to die or drown.

When soil is super saturated is can become semi-liquid in consistency and how it acts. The most obvious expression of this is in mud slides on steep hillsides. When the soil is saturated we can expect damage if there is mechanical, human or animal traffic on the soil. Since the soil is so liquid the traffic can smash the soil particles together and eliminate many of the voids between the soil particles. There are times when this is unavoidable. Trying to complete harvest in a fall like this will often result in nasty ruts from field equipment. Construction sites will also be fighting this same problem as will any livestock confinement facility that is on a dirt lot.

Surprisingly this is not when we see our most serious soil damage occurring. The damage and problems from super saturated soils are obvious and we will often try to avoid being on soil at these times, and we know that we’ll have to take some measures when it dries down later to fix these problems. The biggest problem comes when the soils are a little drier. The soil may not even be muddy on the surface. It may be dampish when you turn it over with a shovel but you’re not leaving obvious ruts, maybe not even depressions from equipment tires. This is when that vicious demon known as compaction really raises it’s ugly head.

Compaction is the official name that we give when soil particles get pressed together and some of the voids are eliminated. Compaction greatly changes the structure of the soil. Compacted soil becomes harder when it dries. It takes in water more slowly and can hold less water available for plants. Roots have problems penetrating compacted soil making the plants more susceptible to drought stress and nutrient deficiencies. Soil can actually work down pretty good when it’s a little wet, but you will wind up with nasty clods. Time and weathering processes will eventually reduce this compaction and cloddiness, but we often have to take a more serious mechanical approach to reduce compaction problems in the field.

It is unlikely that we will have adequate drying conditions to get the soil dry enough to allow much, if any, garden, yard or field work this fall. If you had plans for fall tillage in the garden or field I would strongly suggest delaying it to next spring. Then use extra care next spring to still avoid working wet soil. Compaction is a nasty creature that we often can blame on no one but ourselves, our haste and our impatience. Let’s keep that compaction creature under control and give that wet soil some tender loving care!

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