Cold winter days don't necessarily stimulate excitement about outside garden chores. But a fire in the stove, a cup of coffee, and some gardening magazines provide opportunity to plan for and daydream about your 2015 garden.
If you need help continuing to the next step in the process (nap time), let's consider a basic soil science principle: soil pH.
Soils in the Arkansas Ozarks tend to be naturally acidic. Extremely acidic conditions can exist which negatively impact soil fertility. Specifically, plant nutrients are present in the soil, but in compounds unavailable for plant uptake. Imagine a similar situation in which an American tourist is trying to spend U.S. dollars at a street market in a foreign country. The dollar must first be exchanged into a currency acceptable to the street vendor before it has purchasing power. Likewise, northwest Arkansas soils may contain nutrients needed for plant growth, but before they can be absorbed by plant roots, they must first be "exchanged" into a different "currency" acceptable to the plant.
For acidic soils, lime is the "teller" which allows conversion of nutrients from unusable compound into plant-acceptable forms. Ideally, lime should be applied three or four months ahead of planting date because chemical changes that raise soil pH occur slowly. However, the correct time to apply lime is when you learn you need it.
Similarly, if acid-loving plants are placed in a soil whose pH is too high, stunted growth and yellow leaves with green veins are common symptoms. This is due to lack of available soil iron, a condition created by, you guessed it, iron in the wrong form. We commonly see this in azaleas and blueberries when soil pH is higher than 5.2 or so. To correct the condition and lower pH, sulfur applications are usually recommended.
If yours is a productive garden, soil pH is probably already acceptable. But, when cropping new ground, the prudent gardener will determine soil fertility and pH well ahead of planting (using soil testing). You should also research the pH requirements of the desired plant and remember different species within plant families may have differing soil pH preferences. For example, inkberry (Ilex glabra) prefers a pH between 4 and 5, while Japanese holly (Ilex crenata) does best when pH is between 5 and 6.5. Although these differences may seem small, remember that a soil with pH 4 is one hundred times more acidic than a soil of pH 6. Blah, Blah, Blah, ZZZZZZ........ ZZZZZZ.........
Alright, wake up! The soil science lesson is over and your coffee is cold. Let's summarize. If it has been two or more years since you collected garden soil samples, or if you are planning to crop new ground, make plans to submit samples to the Extension office for a free analysis. You still have time to soil test before gardening chores begin in earnest, but time's a wastin.' Call our office if you have questions about sampling procedures or for help interpreting the report.
Neal Mays is the Benton County extension agent. He may be contacted at [email protected] or by calling 479-271-1060. Opinions expressed are those of the author.
Editorial on 03/04/2015