Clay soil is a challenge, since heavy clay soil drains slowly and retains moisture longer. After the soil dries completely, it becomes hard and brittle, often with fissures on a cracked surface (courtesy: gardendesign.com).
By John Green, Texas Certified Expert Gardener, Orange County, TX
Can we all agree that summers arrived in SETX? Early morning temperatures are 70+ degrees…moist and muggy which leads into daytime temperatures of 90 F or greater. According to The Old Farmer’s Almanac (a reference publication initially published in 1792), summer officially begins June 20th. The publication is ‘semi-reliable’ resource having twelve-month insights useful for gardeners and farmers (weather prediction accuracy is nearly eighty percent)! Farmers and gardeners have used this publication as a valuable resource for hundreds of years, to aid them in making planting decisions. Drum roll, please…the summer temperature prediction for our area of Texas and Oklahoma is anticipated to be the hottest in the country! News flash…was this not anticipated?
Fortunately, most local areas have received ample rainfall this past week, which was a welcome respite and truly needed. It is enjoyable for me walking through the gardens immediately following rain events. The air is cooler and fresh, that makes harvesting fruits and vegetables or even weeding beds…more pleasurable!
Most plants share one common characteristic- they require soil to grow and flourish (there are scores of exceptions), regardless of whether plants are large or small, annual or perennial, flowering or not. Sadly, soil is most often overlooked by many new and seasoned gardeners that simply don’t take soil seriously. Some gardeners purchase the least expensive soil available and ‘hope’ for the best. Seasoned gardeners have learned through trial and error, to appreciate the value of a robust soil medium even though the cost can be considerable. Good quality soil will make the difference in a successful gardening experience over a poor soil mix, which often leads to plant failure and poor yields! Most gardeners are familiar with garden terms such as pH, microbes, and humus but how do they affect the soil?
Let’s start with pH, which is critical for plants, since different plants require soil with various pH ranges, such as acidic (less than 7.0), alkaline (greater than 7.0), or neutral (7.0). Ask yourself why plants need different soil pH’s? It is important to note that nutrients ‘move’ through the soil at different rates and the more acidic the soil, the faster the rate of movement. Acid-loving plants such as blueberry, camelia, hydrangea, or azalea, when planted in alkaline soil, will not receive nutrients at a rate fast enough. Applying fertilizer will not correct the issue since the soil pH is too high, minimizing nutrient availability. Diminished nutrient availability ‘flowing’ means these type plants will languish, succumbing to nutrient deficiency, in other words, starving.
Determining soil pH is one of the main reasons to have soil tested before planting anything and again every 2 or 3 years. The soil analysis report provides useful information including amendments required with amount necessary for growing plants of choice. It is always best to gather soil samples and have them analyzed following guidance provided from the local County Extension office, which for us is Texas A&M AgriLife County Extension Services.
It is important to note that ‘salt buildup’ within soil is problematic over time. Utilizing commercial synthetic fertilizers contain mineral salts. Salt causes soil nutrients to bind together to a point where plants can no longer uptake nutrients. Another issue created by salt build up is soil compaction which decreases the activity of beneficial soil microbes and increases pathogen activity that is known to cause disease. Organic fertilizers contain zero salts and are much better for the soil. Plants are unable to determine whether fertilizer is synthetic or organic, but the soil can!
Humus is finished compost, an organic matter that provides beneficial microbes and nutrients. Humus also absorbs 4 to 5 times more moisture than clay soil, storing it thus making nutrients easily available for plants. Humus reduces nutrient leaching and reduces the need for additional fertilizer. Humus plays an important part in reducing soil erosion.
Microbes present in the soil are the key to producing humus without them, organic matter will remain intact, requiring a greater time interval to break down. The initial 2-4 inches of good quality garden soil contains almost a billion microbes! It takes many types of organisms (bacteria, algae, fungi) to break down organic material to humus. Remember, humus (compost) is a gardener’s best friend and will help the garden soil thrive, allowing gardeners to reduce or eliminate synthetic fertilizers!
Soil in Southeast Texas (especially Jefferson and Orange County’s) is nutrient dense (soil type is known as Coast Prairie Soil) but is not optimum for most ornamental or vegetable plants, as it can be difficult to cultivate. Clay soil is a challenge, since heavy clay soil drains slowly and retains moisture longer. When the soil does dry out, it becomes hard and brittle with a cracked surface.
Creating ‘good’ soil structure is a process which takes time and requires soil amendments to loosen the soil, free up nutrients while retaining moisture. There are numerous ways gardeners can build soil structure. Adding organic matter, elevating planting areas, top-dressing, and incorporating amendments into the clay soil will build structure.
Organic Matter– improves drainage and soil structure by lightening heavy clay soil. It provides beneficial nutrients that feed microorganisms in the soil. Adding aged manure and compost multiple times during the year by incorporating a 2 to 3-inch layer, then gently working the organic matter into the soil. Continue adding organic matter throughout the season, such as shredded leaves, grass clippings, or additional compost.
Raised Beds- elevating planting areas (raised beds) can greatly assist drainage. Raised beds can be simple mounds of soil such as in a conventional vegetable garden, or defined and structured, physically elevated from ground level. Often raised beds are constructed of wood, brick, stone, or other materials. If constructing a raised bed, ensure the beds’ size (width) allows for easy reach from the middle to either side. Raised beds should not utilize existing soil from the landscape… as this will defeat the purpose of building the raised bed. Purchase quality garden soil, compost, and aged manure to fill the beds.
Mulch- helps to keep weed growth and evaporative moisture loss to a minimum during the seasons, especially summer. Before planting the area, remove the mulch and place it on the garden path since it may not have decomposed enough to be worked into the soil.
Expanded Shale- is a sedimentary rock comprised of flakes of clay and other minerals such as quartz and calcite. Expanded shale is found in Texas (eons past when Texas but an enormous lakebed). It is lightweight, gray, porous gravel, closely related to perlite and vermiculite. Adding it to heavy clay soil lightens and aerates the soil but can retain approximately 40% of its weight in water. Expanded shale does not easily break down, meaning clay soil will remain friable for many years once incorporated into the soil.
Greensand– is an organic fertilizer containing mineral deposits from the ocean floor. It enhances soil structure, allowing for increased root growth and excellent for overall plant health, providing required nutrients. Greensand isn’t water soluble, so it needs to be incorporated into the soil at a rate of 30lbs per 1000 feet.
So long for now fellow gardeners, let’s go out and grow ourselves a greener, more sustainable world, by maintaining ‘good’ soil structure, one bed at a time! For answers to your gardening questions, send me an email: jongreene57@gmail.com.
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