Importance of soil in agriculture - class-VI

The lithosphere is the solid portion of the Earth. It is a dense shell of material, that surrounds the entire planet. Even though most of the Earth's surface is covered with water, underneath, that water is a solid layer of rock. With the exception of ice, basically any solid non-organic material on the Earth is from the lithosphere. This includes soil, rocks, sand, etc.

Soil, as we know an important abiotic component of our environment. It provides nutrition and water to grow crops. They hold the roots of the trees and are extremely necessary for the proper growth of plants and trees. In the absence of proper nutrients in the soil, the plants and trees show nutritional deficiencies and retarded growth.

The roots of the plants are held firmly in the soil. Different types of soil have different texture and particles. They have different levels of minerals and nutrients embedded in them. Roots absorb water from the soil by the process of osmosis. Along with water, mineral nutrients also enter the soil.

Mulching refers to covering of harvested field with plant litter or polythene of low density, in order to decrease run off, prevent growth of weeds and retention of water.

• Pedology is the study of soils in their natural environment. It is one of two main branches of soil science.
  
• Physiology is the branch of biology that deals with the normal functions and processes of living organisms and their parts.
• Kinesiology is the scientific study of human or non-human body movement. Kinesiology addresses the physiological, biomechanical, and psychological dynamic principles and mechanisms of movement.
  
• Limnology is the study of the biological, chemical, and physical features of lakes and other bodies of fresh water.

Soil is the uppermost layer of the Earth's crust that supports plant life and provides essential nutrients, water, and anchorage for organisms.

Pedology is the study of soils in their natural environment. It is one of two main branches of soil science, the other being edaphology. Pedology deals with pedogenesis, soil morphology, and soil classification, while edaphology studies the way soils influence plants, fungi, and other living things. The quantitative branch of pedology is called pedometrics. Hence, pedology is the science of soil.

(a) Soil; because man and animals are biotic factors and temperature is climatic factor.

Edaphology is concerned with the influence of soils on living things, particularly plants. It includes the study of how soil influences humankind's use of land for plant growth as well as man's overall use of the land. It is one of two main divisions of soil science, the other being pedology. Hence, edaphology is the study of soils.

Sheet erosion is defined as the uniform removal of a thin layer of soil from the land surface by runoff water. Unlike rill or gully erosion, it does not create distinct channels.

Option A is incorrectly matched - Therophytes are annual plants with surviving buds above soil, not 'well above'. Cryptophytes have buds underground, Hemicryptophytes have buds on soil surface, and Chamaephytes have buds at ground level.

Top soil is the topmost and outermost layer of the soil, which is usually 2 inches to 8 inches layer. It is generally dark in colour due to humus, i.e., partially decayed organic matter, soil particles and living organisms as soil bacteria etc. 

Decomposers also break down the bodies of dead organisms resulting in nitrogen being returned to the soil as ammonia. In some conditions, denitrifying bacteria in the soil break down nitrates and return nitrogen to the air. This is usually in waterlogged soil. Hence, making it unavailable for plant roots.
So, the correct option is 'Denitrifying bacteria'

The forces like exogenic and endogenic can create a lot of landforms. Examples include Mountains, Plateaus, and Plains.

Soil contains minerals because they are made up of rocks by the process of weathering.

Sticky soil, which contains a high proportion of clay, is pliable and retains its shape well, making it ideal for molding models of vegetables. Other soil types lack the necessary cohesion and plasticity for fine modeling work.

Soil is the primary reservoir for minerals on Earth, resulting from the weathering of rocks and providing essential nutrients to plants.

The wilting point is the minimum amount of water in the soil that a plant requires not to wilt; below this level, the plant cannot extract water and will permanently wilt.

The lithosphere serves as a source of minerals. The minerals supply the basic materials, required for making a variety of commodities, which man uses daily. The lithosphere is also the major source of fuels, such as coal, petroleum and a natural gas. 

Green manures are added to the soil to increase the productivity. Manures is of natural origin. The presence of nutrients in manure have a great role in increasing soil fertility. Biofertilizers are organisms which enrich the soil with nutrients e.g., Rhizobiumin symbiotic association with legume plants.

Lithosphere is the outer solid crust of Earth, which we call land. Its upper weathered part forms the soil.

 Deforestation is a direct cause of the erosion happening in tropical rain forests. Once plant cover is gone there are no roots to hold the soil in place during heavy tropical rains, which then wash away the topsoil and the nutrients necessary to regenerate future vegetation.

As rock becomes broken down through a variety of processes, such as weathering and erosion, the particles become ground smaller and smaller. The four main bases in a soil are Nitrogen, Phosphorus, Iron and Potassium.

Explanation: Virtually all soil profiles are composed of a number of distinctive layers, termed horizons, interpretation of which is the key to understanding how the soil has formed.

Soil provides the physical medium, water, and mineral nutrients necessary for crop growth, making it the most fundamental component for agriculture.

Soil is considered a renewable resource because it is continuously formed through weathering and biological processes, although the rate of formation is slow.