The type of soil in your garden plays a huge role in determining how well plants grow. Different plants are adapted to different types of soil and growing them in the wrong type of soil negatively impacts growth. Understanding the different properties of soil and how they affect your plants helps you select the best plants for your garden. It also serves as a guide for whether or not to amend the soil and how often to fertilize and water.
The main 3 Key factors of soil that affect plant growth
When gardeners talk about soil texture, they’re referring to the size of particles in the soil. Particle sizes are categorized as clay (small particles), sand (large particles), or silt (particle size between clay and sand). If the soil is mostly composed of tiny particles, it is clay soil.
If the soil is mostly composed of large particles, it is sandy soil. Loamy soil has roughly equal parts of sand, silt, and clay.
Soil texture affects how well the soils retain water. how quickly the soil drains and the speed at which soils warm up in the Sun.
Clay soils do not drain well, hold high amounts of water and warm up slowly. Sandy soils drain very quickly, do not hold water well, and warm up quickly.
Loam and other soils that fall in between sand and clay have varying characteristics depending on the size of the particles.
Different types of plants do best in different soil textures. Citrus trees (citrus spp, U.S. Department of Agriculture plant hardiness zones 9 through 11), for example, grow well in sandy soils because they need loose soil that drains well and warms up quickly.
Clay soils would be too heavy for citrus trees and hold too much water around their roots. some plants, however, grow well in clay soils, especially if you loosen the surrounding soil before planting and add organic amendments to improve the soil structure. One example is the Tartarian dogwood (Cornus Alba, USDA zones 3 through 7), which adapts to most soil conditions.
2. Soil Structure
Soil structure describes how the sand, silt, and/or clay particles are arranged in the soil. It also refers to the pores, or spaces, in the soil, as well as the soil particles’ ability to group together and form aggregates. The soil structure affects drainage, water holding capacity, how much air is in the soil, and how easy it is for roots to grow.
Good garden soil typically has a granular structure, with several sizes of particles and aggregates about 50% pore space.
Heavy clay soils and compacted soils develop a platey or massive structure, which allows very little drainage and has few pores.
Sandy soils have a single grain texture which drains quickly but since the particles and pores are all about the same size it doesn’t retain water well.
Soils with blocky and prismatic structures have larger aggregates and pores to allow moderate drainage.
Best Soil for plant growth
Plants typically grow best in soils that contain 40 to 45 percent loamy soil, 5 to 10 percent organic matter, and 50% pore space occupied by both air and water. Soils that have a Platey or massive structure are hard for plant roots to penetrate and will stunt plant growth. Soils with a grainy texture don’t hold water well, and plants that aren’t drought-tolerant wilt easily in these soils.
You can improve soil structure for most garden plants by adding organic matter. Organic amendments improve the water holding capacity of sandy soils and the drainage in clay soils. For most planting beds, apply by spreading a 1 to 2-inch layer of organic matter, like well-rotted compost, over the planting bed, and working into the soil to a depth of 6 to 8 inches.
Keep in mind that some plants grow best in unamended soils. blanket flower (gaillardia X Grandiflora, USDA zones 2 through 10), for example, needs well-drained soil with low fertility and grows best in sandy soils without organic amendments.
Other plants, like daylilies (Hemerocallis SPP. USDA zones 3 through 10, depending on cultivar) thrive in a variety of soils, including sand or heavy clay.
The cation exchange capacity, or CEC, describes the soil’s ability to hold positively charged ions. this is important for gardeners because CEC affects nutrient availability in the soil. The smaller the particle size, the higher the CEC of a particular soil. this means that clay soils hold nutrients longer than sandy soils.
Gardeners can add larger amounts of fertilizer less frequently to clay soils because the nutrients will stay in the soil longer.
In sandy soils, gardeners can fertilize more frequently using smaller amounts of fertilizer since the nutrients leave the soil quickly. you can check the CEC of your soil with a soil test.
The pH scale describes the acid / alkaline reaction in soil. Soil pH directly affects plant growth because it helps determine the availability of nutrients.
Soils with a pH of 7.0 are described as neutral. A pH between zero point zero and 6.9 is described as acidic, and a pH between 7.1 and 10 is described as alkaline. Most soils have a pH range between 4.0 and 8.0. you can check the pH of your soil with a soil test.
Most plants grow well in a pH range of 6.0 to 7.0, though some plants thrive in different pH conditions. Plants like Japanese Barberry (Berberis thunbergii, USDA zones 4 through 9) and Sargent crabapple (Malus sargentii, USDA zones 4 through 8a) grow well in neutral or slightly acidic soil and also tolerate alkaline soils. Other plants, like azalea bushes (Rhododendron spp., USDA zones four through nine, depending on the species), require acidic soil — pH 4.5 to 5.5 — to thrive and won’t grow well in soils that are neutral or alkaline.
Why is soil so important to plants?
The plants that produce fruit and vegetables are rooted in soil, but what exactly is soil? Soil is a living substance different elements whose interaction determines the health of the plants it supports. Soil contains minerals such as sand. silt and clay. The proportion of minerals in the soil determines its texture. It is the organic matter called houmous that determines the soil’s fertility. The humus is constantly being regenerated by the living organisms it contains.
Soil is a rich reservoir of microorganisms. The microorganisms facilitate the absorption of carbon in the soil, reducing the polluting effects which contribute to climate change and by merging with roots bacteria and fungi these earthy heroes protect the plant from disease and provided with water and all the nutrients it needs.
One gram of plant-covered soil contains around 1 billion bacteria from between 5,000 and 25,000 species. The other starve of the soil is the earthworm of which there are some 25,000 per hectare. In one year several hundred tons of Earth passed through the digestive tract of just a single one of these tireless workers. Worms also create tunnels that help plants access nutrients and speed up the absorption of air and water which also prevents soil erosion.
Soil health has a direct impact on human health but the soil is in danger the use of pesticides and chemical fertilizers are sterilizing the soil and killing living organisms. Deprived of organic nutrients plants are becoming dependent on chemicals. Their natural defenses are weakened and they need ever greater amounts of artificial inputs just to survive.
Farmers who have until relatively recently benefitted from the free and natural service provided by soil are in turn at the mercy of chemical inputs. A vicious circle develops whereby ever greater sums of money are required to buy more and more products.
Plants that are deprived of natural nutrients produce fruit and vegetables of inferior quality which are low in vitamins and essential nutrients. They also contain potentially harmful pesticide residue. urgent action is needed and there is a solution the solution is agroecology.
Agroecology respects the soil’s natural life cycle. It can also reinject new life in infertile soils by counteracting the harmful effects of chemicals. How? By feeding the soil with compost, fertilizing it with green manure, practicing crop rotation, and by not harming its underground organisms by digging or plowing it up.
Agroecology allows us to practice a form of Agriculture that respects soil life. whilst providing enough healthy, varied, and tasty food for everyone.
It is crucial for us to remember that living and healthy soil is good for our health, good for farmers, good for the environment and the climate, and good for the earth.
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