Time and time again I speak of the need for good drainage.  Proper drainage is critical to successful gardening be it tree, shrub, flower, herb, or vegetable.  What goes on beneath the surface of the soil dictates the growth of the upper portion of the plant.  Much like our main arteries and capillaries, a tree has large roots and smaller feeder rots.  The feeder roots are very tender and fibrous.  The feeder roots are like a powerful sponge, absorbing the bulk of the water and nutrients a plant needs to survive and flourish.  Left to soak for long periods of time, feeder roots decay, thus ceasing the transfer of life sustaining materials to the upper portion of the plant.

    The color of soil tells us lots about its content.  In addition to good drainage, soil needs organic matter and microbial (bacterial) activity.  The organic matter provides moisture and nutrient retention, and the "critters" (or microbes) perform the task of breaking down nutrients into an available form for use by the plant.  Clay, which we curse, has an ionic charge which holds nutrients in place.  The proper amount of microbes, moistures, and pH will release these nutrients from the particle for use by the plant.  The uncharged sand holds nothing and the moisture quickly washes the nutrients down past the root zone.

    Dark brown soil indicates a high content of organic matter and good air content.  This is a gardener's dream.

    Soil which is reddish in color indicates a low level of organic matter, which is correctable, but a high level of air.  The air in the soil oxidizes the minerals yielding a reddish color.  Rust on iron is red due to "oxidation" or the presence of oxygen.

    Soils which are yellow or gray indicate a low level of organic matter and very poor air content.  I have seen soils on slopes the color of mustard, or as gray as the Old Mare herself.  The bacteria which might be living in this soil could be "anaerobic" meaning that it grows in the absence of oxygen.  The critters are generally detrimental to feeder roots.  Anaerobics are the same guys that make us so unpleasant when we forget  to use our Right Guard.

    I mentioned poor drainage on slopes earlier.  Often, when I suggest to a customer that they may be experiencing a drainage problem, their first response is, "This is a sloped area."  Sloped areas have often lost all of their organic matter and loaminess to erosion, leaving only hardpan which is incapable of absorbing surface moisture, rocky, and very tightly packed with residual clay soil.  Indeed, slopes often have the worst drainage.

     A visual inspection as described above is very helpful in determining soil drainage properties.  Additionally, in questionable drainage situations, pre-dig your hole and fill it with water.  In periods of heavy rainfall your hole should drain empty in 8 to 10 hours.  In dry periods, the water in the hole should be gone in an hour or two.  If water continues to stand, do not plant anything which would require good drainage.  Exciting stuff, eh?  The subject is important to success.  See you next week.