A soil test is a great tool for improving the quality and quantity of your garden.
Soil testing is a procedure used to determine any chemical deficiencies in the soil before planting is done. It is best to perform a soil test at least two months ahead of planting schedule. This allows enough time for the right amount of fertilizer and lime to be added if needed. It also gives the soil enough time to react to the additives. Using too much fertilizer can be just as harmful as not having enough nutrients in the soil. You can always add more fertilizer to the soil but if too much is applied; there is little that can be done to remedy the situation.
In order for plants to grow properly and at an optimum rate, certain elements must be present in the soil. There are a total of sixteen elements that are essential to plant growth. These sixteen elements consist of both minerals and non-minerals. The non-mineral elements are present in water and air. A farmer has little control over these elements. They are carbon (C), hydrogen (H), and oxygen (O). Soil testing does not measure these elements. The other thirteen mineral elements are all found in the soil. When the soil becomes wet from rain or watering, the minerals dissolve and are absorbed by the plant through its roots. If the soil does not contain enough of these minerals, plants will not grow properly. A soil test provides an accurate measurement of these minerals at a given time. It helps farmers and gardeners decide which nutrients to add to the soil and the amount to add. It is a good idea to perform a soil test every two to three years since soil composition can change drastically. Plant growth and harvesting on a regular basis depletes the soil of its nutrients. The fertility of the soil will change during the crop season.
Elements derived from the soil are classified into two groups. The first group is the macronutrients. These are nutrients that plants require an abundance of to grow well. The three major macronutrients are nitrogen (N), phosphorus (P), and potassium (K). It is not uncommon for soil to be deficient of these nutrients. These are also referred to as the primary macronutrients. The secondary macronutrients consist of calcium (Ca), magnesium (Mg), and sulfur (S). These nutrients usually occur at an acceptable level in most soils. If there is a deficiency it will most likely be the amount of sulfur in the soil. The second group, micronutrients, is also needed for proper plant growth but plants require a much smaller amount of these nutrients than the macronutrients. The micronutrients group consists of boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo), and zinc (Zn). Boron, iron, and zinc deficiencies are the most common. However, these are likely to occur only in certain regions.
Another major factor that affects growth is the pH level of the soil. This is often referred to as the most valuable part of the soil test. The soil pH level, which can range from 0-14, affects the availability of elements in the soil. It will determine whether the soil is acidic, alkaline, or neutral. Every plant has a different optimum pH level but at 6.5 most elements respond well. If soil is outside of the pH level, nutrients are trapped and plants cannot absorb them. A level of 6.5 increases bacterial growth and causes decomposition. It is during this decomposition that elements are released in the soil for plant roots to absorb. If the soil level is too acidic, the pH level needs to be increased. This is most often accomplished by the use of lime. When there is too much acid in the soil it does little good to use any fertilizers because plants cannot absorb them until the pH level is corrected. If the soil contains too much alkaline, the pH level is lowered by the use of compost or other organic materials. A pH level of 7.0 is considered neutral. Any reading below 7.0 is on the acidic side and anything above is on the alkaline side.
How to Perform a Soil Test
It is most common to conduct a soil test in the spring before planting. If the pH level of the soil is suspected to be at an undesirable level, you can conduct the test in the fall, which will give the soil plenty of time to adjust.
Steps:
1. Request kit from a soil-testing lab
2. Use the proper equipment to obtain samples. A soil probe is best but a spade or garden shovel can also be used.
3. Collect several samples from each area to be tested. The samples from each area should be mixed together but do not mix soil from different test areas. For example, soil taken from the garden test area should not be mixed with soil taken from the flowerbed test area.
4. Be sure to measure the proper level for the soil sample. Four to six inches is usually appropriate for vegetables or flowers. If you are sampling an area where only grass will be grown, four inches should be a sufficient level.
5. Package and send the soil as instructed.
The results of a soil test are only as accurate as the test itself. Be sure to follow all directions as closely as possible. If done properly, a soil test can provide you with all the information you need for a healthy abundant garden or lawn.
