Soil types are defined ultimately by particle size which dictates its behavior and ability and inability to perform different tasks.
Clay soils contain smaller particles that stick together and are not very porous. Although these soils are typically nutrient rich and will not leach these nutrients quickly, it is also nearly impossible for a plants root system to cut through it to be able to absorb the available nutrients. Making the soil more porous by amending it, allows plants to get a deeper, vaster root system that can absorb more nutrients. Clay soils can turn into a brick in the summer heat or a soggy marsh in lowland areas, making it unsuitable for most plant life either way. Improving porosity allows plants to establish a deeper root system allowing for better winter hardiness as well.
Knowing what your soil has and what it is lacking will help you make the right decision when it comes to amending it. If clay needs more porosity and better drainage then it would make more sense to amend it with larger particle matter. If clay is nutrient rich, adding nutrients can become less of a priority. Soil pH is the first step in planting anything, as this is what determines the plants ability to work efficiently.
Think of sand particles as little rocks. There is more air between them because they are larger particles than those of clay but with an absence of organic matter, so there is nothing to slow water and nutrients from just leaching right out. Since porosity is not the issue as it is in clay, you are going to amend it differently. Sandy soil is nutrient deficient and does not hold moisture very long so let’s work on fixing this.
Soil conditioner does not add much nutritional value to soil when added to clay but it does help make clay soil more porous. It is a bigger particle; therefore helps aerate the soil and make it more navigable for roots in search of water and nutrients. Since soil conditioner has the ability to hold onto water, it makes a good addition to sandy soils as well as clay.
Peat moss may be a better addition to sandy soils because it has the ability to hold 20 times its weight in water. It also gives nutrient a better vessel to adhere to. Peat moss makes a great amendment for many trees and shrubs because many plants prefer acidic soil and peat has a pH in the range of 4.
Composted manure is used by farmers to improve soil fertility organically and to add beneficial microorganisms to the soil. It is a great addition to clay and sandy soil to improve fertility and a great organic way to improve fertility to any soil. Composted cow manure is aged and mixed with other organic matter, so the smell is about gone by the time it gets to your garden.
Top soil is used more of as a filler. Where it is good for filling holes in the yard, it is not known for its great nutritional value, water retention capabilities or its ability to improve any type of soil much.
Having dealt with Georgia’s tough clay, amending the soil has become a science to me. Having planted in it professionally for the last 26 years, I have come up with my method for amending the soil. Because planting with anything that is a wood product can tie up available Nitrogen I use 25% composted manure with 25% soil conditioner and 50% existing clay soil. The manure brings nitrogen with it and the beneficial microorganisms as well. You can substitute Garden Soil for the Soil Conditioner or Peat Moss because it’s just a combination of both.
Plants grow natively where they do because of their ability to adapt to their surroundings. Whether it is climate, rainfall, temperature or soil type, different plants have different requirements. It is usually the non indigenous plants that require the largest swing in soil change. Planting vegetables in sand usually requires heavy amending and constant feeding since they are heavy feeders and not designed so well for sand. Supplemental nutrients like Iron and calcium are mandatory to prevent diseases like Blossom End Rot.
Water soluble fertilizers like Miracle Gro include the essential micro-nutrients that plants need and can be used as frequently as every 2 weeks. Specialty fertilizers like Vigoro Vegetable Fertilizer also include these micros and can feed for over 2 months.
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