#soil nutrients

Gardening Soil Types

The knowledge of the characteristics of soils will enable you to choose a gardening soil that favors your plants. Therefore gardeners can improve the fertility of their backyard soil to provide the nutrients required by plants. The properties of the types of soils discussed below will enable you to make the right choice for your garden.

Loamy soil - often seen as the ultimate garden soil because most plants will grow in it, this is brown and crumbly in texture and similar to that found on well-worked allotments. It's rarely waterlogged in winter or dry in summer and supports a wide range of plants. Loamy soil is light and easy to dig and is naturally high in nutrients

Chalky soil - typical of south-east England, chalky soil is very shallow, full of clumps of white chalk or flint and is very free-draining. This means it can be bone dry in summer and plants will need far more watering and feeding than on any other soil. Chalky soils are always alkaline, which restricts the number of plants that can grow on them. Planting may also be difficult as spades frequently hit lumps of hard chalk or flint

Clay soil - this is sticky to handle and can be easily rolled into a ball shape. It is naturally high in nutrients so plants that like these conditions should do particularly well. It does pose some problems. In summer, it is often baked dry, with visible surface cracks, making it difficult to get water to plant roots. Yet in winter, it can be constantly wet and water-logging is common. It is hard to dig at most times of the year

Silty soil - is made up of fine grains, originally deposited by a river. The tiny particles give it a silky feel if rubbed between the fingers. It does not form distinct shapes like clay when wet, but it can be rolled into sausage-like strips. Silty soils can be badly drained but are not prone to water-logging.

Peaty soil - the fens of eastern England are very peaty and are some of the country's best farmland. Plants grow happily in it, as long as they can adjust to the relatively acid conditions. Almost black to look at, easy to dig over and spongy to the touch, peaty soil can be soaking in winter and dry during most of the summer.

Soil Components

In order to understand how best to care for the soil, it’s important to know what’s in it. Every sample of soil contains the same basic ingredients in relatively the same proportions. About 50 percent of a soil sample is mineral fragments resulting from millions of years of erosion and sedimentation. These fragments come in three basic sizes: sands (visible to the naked eye), silts and clays (individual clay particles are flat and can only be seen with an electron microscope). The USDA uses the percentage of soil that falls into each one of these size categories to describes soil texture. Soil texture plays a significant role in determining other soil qualities, so find out what’s in your backyard. Soils with a higher percentage of clay often drain poorly, while soils containing a larger percentage of sand have trouble holding nutrients. A soil testing lab can conduct a texture test on any given soil sample, but this isn’t always necessary. Often a simple "feel” test will suffice.

Use these clues:

Clay soil: forms a dense clump when damp Sand soil: feels gritty; won’t form a clump Silt soil: powdery when dry; forms a loose clump when wet About 35 to 45 percent of a soil sample is pore space, which contains water (with water-soluble nutrients) and air. The amount of pore space and the size of the pores is determined in part by the soil’s texture. Sandy soils have larger pores while clay-based soils have smaller pores but many more of them. Just as a colander with a few large holes drains much faster than one with many small holes, a sandy soil drains more quickly than a clay-based soil. About 1 to 6 percent of the soil sample is organic matter. This tiny percentage is the most important part of the soil. It’s a nutrient source for plants, food for beneficial soil microbes and the main ingredient for developing good soil structure — the most important measure of soil quality. "Soil structure” is the way mineral fragments group together, or aggregate. It’s an essential factor in soil and plant health. Organic matter creates good soil structure by binding soil particles together and changing the way they aggregate. It separates clay particles. It binds sand particles to decrease pore spaces and increase water retention. It eventually leads to loose, crumbly, nutrient-dense soil. Living organisms make up the final soil component. Ranging in size from microscopic bacteria and fungi to mice, moles and earthworms (vermacompost), soil life is essential for plant growth. They process the soil, convert certain nutrients into a useable form and many of them (think earthworms) have nutrient-rich castings. Soil life is also partially responsible for aerating soils and helping build good soil structure. Fungal networks beneath the soil surface form symbiotic relationships with plant roots, enabling the plant to gather more nutrients from a larger area.

Soil pH

The measurement of soil acidity — soil pH — is an important quality. Soil pH is represented on a scale of zero to 14, (seven being neutral). Any measurement below seven is considered acidic soil, while above seven is alkaline soil. At certain soil pH values, nutrients are more readily available to plants while at other levels they are unusable. In general, the broadest range of nutrients are available at soil pH 6.5. The exceptions to this rule are blueberries and evergreens, which use copious amounts of iron, a nutrient primarily available at more acidic soil pH values. The only way to determine soil pH is to test the soil. If the test results determine that the soil is too acidic, add lime to raise the soil pH. If the results are alkaline, add sulfur to drop the soil pH. Most soil-test results will advise on the amounts of these products needed to adjust the soil pH appropriately. Keep in mind that plants will eventually use the calcium and magnesium provided by lime for growth, and that these nutrients, along with any added sulfur, may also leach from the soil. Because of this, the soil-pH change they affect is temporary, lasting three to four years at most. It’s important to retest soil pH regularly because it can change easily.

Testing the Soil

To get a good grip on your soil’s fertility, test the soil. Once existing nutrient levels and soil pH are determined, it’s easy to research what’s needed to appropriately adjust them. Soil tests are available from both independent laboratories (found online) and your county’s cooperative extension agency. Most soil tests come with instructions for acquiring a representative soil sample. Retesting soil every few years is recommended. Soil testing is necessary to determine nutrient deficiencies or excesses, plus it provides an exact soil pH measurement and may reveal important information like organic matter content or the presence of heavy metals. (Consider these uncommon soil tests.) An important note: The practice of regularly adding quality organic matter to the soil may eventually eliminate the need for any additional fertilizers. To generate peak fertility, create a healthy, balanced soil with great structure and plenty of active soil life.

Summing Up Soil