Soil Problems, The Science, and Common Solutions by Rebecca Radtke, LCMP Behind The Science and Reading Soil Tests Lab soil tests are a great way to know the ground and better understand solutions. According to Greg LaBarge — Professor, Field Specialist, Agronomic Systems, Ohio State University Extension — in an article on Ohioline, soil test reports help us understand the soil's ability to retain and supply nutrients and organic matter. LaBarge explains that there are three defining soil test factors that are inherent and portray limiting change. For example, while Cation Exchange Capacity (CEC) cannot be altered by management, organic matter can be changed, but it takes years. Further, according to the Oklahoma State University Extension, toxic elements like aluminum and manganese are major causes of plant failure in acidic soils. Because these elements are more soluble, they are problematic in acidic soils. They recommend liming the soil to rid it of toxic elements, as liming raises the soil pH and causes aluminum and manganese to go from the soil solution back into solid form. A soil pH between 6.0 to 7.0 is desirable for nutrients.  Above: Featured in LC in 2018, humates, not be confused with humectants, are prehistoric plant matter that is mined by companies like Live Earth Products, which then incorporates it into various manufactured goods, such as fertilizers and soil amendments. When added to the soil, these humate-based products are credited with enhancing its structure, improving the transformation of nutrients from the soil to the plant, increasing water saturation, and repairing decelerated biological activity. PHOTO CREDIT: LIVE EARTH PRODUCTS PennState Extension explains how to read a soil test report, which is broken down into four sections. The first section includes the contact information. The second shows measured soil fertility levels like pH, phosphorus, potassium, and magnesium. These elements are essential to a successfully growing plant and can be measured in parts per million or pounds per acre. Further, soil pH measures acidity or alkalinity which show readings between 0-14. Under seven means that you have an acidic pH, seven is neutral, and over seven is a basic pH. Nitrogen is difficult to measure despite being integral to plant growth. Some suggestions PennState makes for healthy soil are that acidity is not the same as soil pH and that while recommendations are not given for trace minerals a typical range is found on the back of soil tests.   These graphics show examples of a variety of soil test report ranges. PHOTO CREDIT: GREG LABARGE, OHIO STATE UNIVERSITY EXTENSION Further, the USDA has developed a broad soil property map to give users an idea of their type of soil, however a lab test is the most accurate and should be taken every three years. Some Common Problems and Their Solutions The Western United States faces soil issues such as erosion, salinization, and pesticide pollution. According to Alluvial Soil Lab, precision fertilizer use, based on soil testing, helps prevent nutrient imbalances, which mitigates pollution. They recommend rotating crops to improve soil structure and nutrients, irrigate appropriately, adjusting pH, utilizing Integrated Pest Management, and conserving. An article published by LC in 2018 said that improving the aeration and water absorption qualities of the soil is the main purpose of soil amendments. Dry peat, though it can contain two percent nitrogen, is generally thought of as the most popular of these additives. Coir, bark, and sawdust also fall into this category. North Carolina State Extension says that landscape professionals may confront two issues in densely populated areas. Soil infertility due to poor nutrient availability and compaction leading to improper drainage are commonly seen. These common issues can be tackled in several ways including increasing the size and amount of pore spaces as they recommend having 40% pore space to allow drainage to small pores that then store the water. To achieve this, add sand to clay soil or add topsoil. However, this recommendation is best added to small spaces as it can be costly. For compacted soils, tilling helps loosen the ground and reduce compaction even without amendments. Common Problems Common Solutions Common problems that landscape contractors may encounter other than soil compaction may be yellowing leaves on plants which can be caused by low nitrogen or potassium according to Mississippi State University Extension, which can be remedied by amendments. Further, low magnesium displays itself with interveinal yellowing and can be reduced with added magnesium. Early Blight (Alternaria linariae) — a fungus — will show with small circular brown lesions and a yellow halo around the lesions. According to the University of Maryland Extension, this fungus overwinters in soil and plant debris and can be transmitted on seeds and transplants. It can be treated with adequate spacing, close monitoring, and mulching. Additionally, synthetic and fixed copper fungicides can also be helpful. Another common issue you may come across is low producing plants. When plants have small leaves, adding a balanced fertilizer to the soil is the best solution as these smaller yields could signal a nitrogen, phosphorus, and potassium deficiency. On the other hand, tilling the soil before planting will help a tree grow successfully. According to McCullough Tree Service, adding soil amendments to a tree can assist in successful growth. For example, organic matter with soil conditions and manure promotes growth. Amendments like tree bark that break down slowly help as well. Basic Field Soil Testing Healthy soil provides nutrients to plants and trees so knowing your soil type is key to success. The Penn State Extension explains that the ideal soil is equal parts sand, silt, and clay, referred to as loam. This type holds its shape but crumbles when held lightly, but it is good for planting as it is fertile and drains easily. Clay soil, however, is dense and has 25% more clay particles but holds its shape and doesn't crumble easily. These descriptions can help you distinguish the soil type in the field. If you would like to see what kind of soil you're encountering before a proper lab soil test, utilize the USDA Web soil survey platform "websoilsurvey.nrcs.usda.gov" for a basic idea of your area's soil type. For a basic field test, check out the color of the soil before placing and shaking it in a jar with water to see if it holds shape or crumbles to verify that you have a loamy soil variety. Once the soil has settled and the clear water is at the top of the jar you can read the results. Organic matter may sit at the top or be floating, above that are tiny clay particles, then come small silt particles and at the bottom will be the heavier particles like sand and rocks. Based on that if you have 20% clay, 40% silt, and 40% sand you have loamy soil according to the National Environmental Satellite, Data, and Information Service.  This image shows how desirable soil will crumble in a basic field test. |
