How is soil important in plant growth ?
..answer, it depends on the plant as each plant may have it's own ideal soil condition that enables good growth.
Sandy soils have a light texture and loose structure, which cause them to drain quickly and not hold water well. This can lead to low fertility, but with the addition of some compost, manure or leaf mold, sandy soil can grow a satisfactory garden. This type of soil is dries quickly and is easy to work.
The size of the particles that make up soil determine its texture. Sand particles are large and surrounded by air pockets, which provides plenty of open spaces for water to move through. When you pour water onto sandy soil, the water doesn't pool on the surface, but soaks right in. This is a real advantage in damp weather, but can be a problem during a dry spell. Water drains so quickly through sandy soil that it washes away most of the nutrients. Adding organic matter, such as compost, manure, leaf mold or some clay soil, before planting can help increase water retention.
The way soil holds together is determined by its structure. Sandy soil has a loose structure with large pore spaces, which allows for easy movement of roots through the soil. But sandy soil doesn't hold together well and needs to be amended with organic matter to give it better structure. The ideal garden soil, often described as having "a crumb-like structure," is created from a combination of large sand particles, smaller loam or clay particles and organic matter for fertility.
The optimal soil pH level for most vegetables and flowers is between 6 and 6.5, with a pH of 7.0 being neutral. Test the pH of your soil using a test kit, which you can buy at garden centers or home improvement stores. An advantage of sandy soil is that pH level is more easily changed than in heavier soils, such as clay.
Advantages of Sandy Soil
Sandy soil has its good points. It is easy to dig and can be worked earlier in the spring than other soil types. It is not as susceptible to frost heave as clay soils. This is a condition where the soil is lifted up when the water inside the soil freezes, and it can push plants out of the ground. With the addition of some organic matter, the light texture and open structure of sandy soil is good for growing many varieties of vegetables and flowers, and is well suited to annual root crops, especially potatoes (Solanum tuberosum). Also, use compost to improve the fertility and water retention of sandy soils.
A good gardener will consider the soil type in relation to the needs of a plant.
Each soil type has different properties - divided into several categories.
Sometimes called basic soils, they are always very alkaline. Chalk is a solid, soft rock which breaks down easily. It is very free draining, and chalky soils hold little water and dry out easily. Chalky soils are fertile, but many of the nutrients are not available to plants because of the high alkalinity of the soil, which prevents the absorption of iron by plant roots.
The clay forms a heavy mass which makes it difficult for air, water and plant roots to move through the soil when wet. Once dry they form rock-hard clots. Blue or grey clays have poor aeration and must be loosened in order to support healthy growth. Red colour in clay soil indicates good aeration and a "loose" soil that drains well. Plants can take advantage of the high level of nutrients if drainage is adequate.
Considered to be the perfect soil, a mix of 40 % sand, 40% silt and 20% clay. Due to mix variations loam can range from easily workable fertile soils full of organic matter, to densely packed sod. Characteristically they drain well, yet retain moisture and are nutrient rich, making them ideal for cultivation.
Provided they are not too acid and have effective sub drainage, these are rich in plant foods. Converting existing soil into a peat type soil is achieved by adding large amounts of organic matter. You must avoid making your soil too acid though, and careful choice of organic matter is needed.
Sandy soils generally have a fine grained texture. They retain very little in the way of water, fertilizers or nutrients which means they are extremely poor. Prone to over-draining and summer dehydration, and in wet weather can have problems retaining moisture and nutrients and can only be revitalized by the addition of organic matter. Sandy soils are light and easy to dig, hoe and weed.
Silty soil is considered to be among the most fertile of soils. Silt is often found in river estauries, because the fine particles are washed downstream and deposited when the water flows more slowly. It is also soft and smooth, with individual pieces close together. It too holds a lot of water, but the slightly larger particles make it a little better at draining than clay.