view counter

Rain, Rain, Go Away!

When water replaces air in the soil, plants die

If plants are wilting in your gardens despite all of the rain we have been having, it is due to a lack of oxygen in the soil. This is a bigger problem in heavy-loam soils than in sandy loam or loamy sands. Heavy soils become saturated with water faster than sandy soils because the pores are smaller and thus exclude all the air.
    The roots of plants need oxygen to function. We have received so much rain that air in the soil has been replaced by water. If the problem persists for more than a couple of weeks, there is a good possibility that root rot will kill plants. Under these conditions, it is not uncommon to harvest carrots with rotted taproots. Or to see tomato plants developing roots near the base of stems to replace the dying roots killed by excess water in the soil.
    The problem is worse in gardens that have been plowed and/or rototilled at the same depth year after year. Working the soil to the same depth once or twice each year causes a plow pan to form below the tilled or plowed layer. Plow pans are a compacted layer of soil that prevents the downward movement of both water and roots.
    Plow pan can occur in both sandy and heavy loam soil but happens more rapidly in heavy soils. To determine if your soil has plow pan, try pushing a half-inch-diameter piece of pipe or dowel into the soil. If you have plow-pan, you will most likely be able to force the pipe only six inches deep. In many instances, I have uncovered plow pans so dense that I was not able to penetrate them with my stainless steel auger.
    The problem can be solved by sub-soiling with a special tractor-mounted attachment, by double digging or by varying the depth of plowing or rototilling season to season.
    Sub-soilers are plow-like attachments that penetrate the soil to a depth of 18 to 24 inches, forcing the soil upward and fracturing the pan layer. Sub-soiling should be done when the soil is as dry as possible to maximize fracturing of the pan layer.
    If you spade the garden by hand, double digging means that when you first press your spade in the ground, you remove a spade full of soil and place it to one side, followed by removing another spade full of soil from the same hole. In other words, you are digging into the sub-soil, thus removing the pan layer, then blending it with the surface layer of soil.
    You can delay the formation of the plow pan by varying the depth that you plow or rototill. One year you plow or rototill at a depth of three inches, the next four inches, the next five inches and the next six inches before returning to a depth of three inches.


Share the Bounty

    Let others benefit from your gardening skills by contributing surplus fresh produce to local food banks or pantries. The Bay Gardener donates his surplus vegetables to SCAN Food Bank at St. James Episcopal Church on Rt. 2, which is open for those in need on Thursday and Saturday from 8am until noon.


Ask Dr. Gouin your questions at DR.FRGouin@gmail.com. Please include your name and address.