Soil

TABLE OF CONTENTS Sr. No. | Topic | A | Introduction | B | Types of Soil | C | Crops and Soil | D | Conclusion | E | Bibliography | A. Introduction Soil maybe defined as a thin layer of earth’s crust. It serves as a natural medium for growth of plants as they obtain nourishing substances from it. In fact, much of life on earth depends on soil as a direct or indirect source of food. Animals get nutrients from eating plants in the soil and soil serves as a home to organisms like seeds, spores, insects and worms. Soil is formed when forces of nature such as temperature, rain, wind, waves, animals and plants act on rocks and break them into tiny pieces over a long period of time. Thus soils differ amongst themselves in some or all properties. Some soils are red and some black; some are deep and some are shallow; some are coarse-textured and some fine-textured. Soil is made up of four parts: air, water, minerals, and organic material. Air and water provide nutrients to plants so they can make food for themselves. Organic matter, also known as humus, is made of plant and animal remains in various stages of decay. Minerals are the clay, sand, and silt particles. As the proportions of each of these parts vary from location to location, they form different types of soil which form a system for plant growth. B. Types of Soil Sand Sandy soil has mostly has * mostly sand and no organic matter. It is the heaviest, and allows water and air to move easily through it. * A soil with sandy texture has difficulty in retaining water and thus nutrients are not made available to the plants growing in such a soil. Clay Clay soil has * mostly clay, a little organic matter * Clay is sticky when wet and hard and brick-like when dry. * A clayey soil is poorer in aeration (due to stagnation of water) thus debilitating the plant growth. Loam Soil that is * composed of sand, silt, and clay in relatively even concentration (about 40-40-20% concentration respectively) is called Loam Soil. * It is considered ideal for gardening and agricultural uses. * Loam soils generally contain more nutrients and humus than sandy soils. * Loams retain water easily. * Loam soil is ideal for growing crops because it retains nutrients well and retains water while still allowing the water to flow freely. This soil is found in a majority of successful farms in regions around the world known for their fertile land. Garden C. Crops that grow in it Rich in Loam and Clay / Alluvial soil is a fertile soil rich in potassium. It is highly suitable for agriculture, especially for crops such as paddy, sugarcane and plantain. Sandy to Loam / Red soil has high iron content and is fit for crops like red gram, Bengal gram, green gram, groundnut and castor seed. Loamy Soil Easy to work, good drainage, good fertility, plants love it Clay soil Clay soil is rich in calcium, potassium and magnesium but has poor nitrogen content. Usually very fertile, but has poor drainage and is heavy to work with. It can be rock hard when dry, horribly sticky when wet. * Crops like cotton, tobacco, chilly, oil seeds, jowar, ragi and maize grow well in it. * Roses grow very well in clay soils as they have strong roots and clay provides it with nutrients and anchorage. * Grassy plants and a variety of shrubs can also grown in clay soil. * Potatoes can push their large strong roots and tubers through clay soil. * Legumes, Beans and Peas When the crop is over cut the plants off at soil level, leave the roots to rot under ground so adding organic material and nitrogen from the root nodules that the plants form.  * Soft fruits like apples, pears and plums do well in clay soil as long as it is not waterlogged. Sandy soil is low in nutrient content. Easy to work and easily improved. Free draining - too much so, dries outquickly and relatively infertile. * It is useful for growing trees such as coconut, cashew and casuarinas in areas with high rainfall. * Constantly improving sandy soil with organic matter and use fertilizers has rewards as it is ideal for vegetables, bulbs and annuals. * A large selection of conifers, too, prefer sandy soil. D. Importance of Soil and Its Types “If a healthy soil is full of death, it is also full of life: worms, fungi, microorganisms of all kinds ... Given only the health of the soil, nothing that dies is dead for very long.” - Wendell Berry, The Unsettling of America, 1977 Soil serves as a reservoir of nutrients and water for crops, holds roots, and a favourable tilth. (Tilth refers to a suitable physical condition of the soil and implies, in addition, a satisfactory regulation of soil moisture and air.) Different kinds of soils support the growth of different types of plants and also determine how well that plant life grows. Soil is formed slowly, but can be easily destroyed. Therefore, soil conservation is important for continued support of life. Soil may sometimes get eroded through factors such as wind, running water, overgrazing of animals and human activities such as construction. In addition, soil may also be depleted of its fertility if a particular crop is cultivated repeatedly in the area. High yields and good produce can be achieved only when the right type of soil is used for a certain crop. For areas in which suitable soil is not available, one may add nutrients in the form of fertilizers to enrich it. It forms very slowly and is destroyed easily, so it must be conserved in order to continue to support life. Farmers have very important jobs growing the food and fiber for the world. If we did not have farmers, we would have to grow our own food and materials for clothing. However, a farmer's job consists of many more responsibilities than growing food or fiber. They must also take good care of our soil so we can continue to grow enough food to feed everyone. Soil testing must be done so the farmer knows what type of soil he or she has and can make sure the proper nutrients and the amounts of these nutrients are present. If the proper nutrients aren't present, the levels of these nutrients need to be adjusted so the farmer can grow a healthy crop. By adding fertilizers and rotating crops, farmers replace nutrients that leaching and growing plants have removed. Farmers also make sure there is a high level of organic matter in cultivated soils. Soil is one of the environment’s most important resources. Soil, along with sunlight and water, feeds plants, houses organisms responsible for nutrient cycling, affects primary productivity, and influences plant community diversity. Although it is not an easy medium to study, it is worthwhile to delve belowground because soil is a key component to research involving plant and soil community responses to climate change, invasive weed encroachment, and plant community composition and productivity. Consequently, soil is a resource that must be conserved. In order to be conserved it must be adequately studied and understood. Links http://www.krishiworld.com/html/soils1.html http://www.english-gardening.com