<<–2/”>a >a href=”https://exam.pscnotes.com/soil/”>Soil consists of rock and sediment that has been modified by physical and chemical interaction with organic material and rainwater, over time, to produce a substrate that can support the Growth of Plants.” Soils are an important natural resource. They represent the interface between the lithosphere and the Biosphere – as soils provide nutrients for plants. Soils consist of weathered rock plus organic material that comes from decaying plants and animals. The same factors that control weathering control soil formation with the exception, that soils also requires the input of organic material as some form of Carbon.
Soils have many different properties, including texture, structure or architecture, water holding capacity and pH (whether the soils are acid or alkaline). These properties combine to make soils useful for a wide range of purposes. Soil properties govern what type of plants grow in a soil or what particular crops grow in a region.
Physical Properties
Soil Texture indicates the relative content of particles of various sizes, such as sand, silt and clay in the soil. Texture influences the ease with which soil can be worked, the amount of water and air it holds, and the rate at which water can enter and move through soil.
Soil texture influences many soil physical properties, such as water-holding capacity and drainage. Coarse-textured Sandy soils generally have high infiltration rates but poor water holding capacity. Silt particles are much smaller than sand, have a greater surface area, and are generally quite fertile. Silts do not hold as much moisture as clay soils, however more of the moisture is plant available. Fine-textured clay soil generally has a lower infiltration rate but a good water holding capacity.
Soil permeability
Soil permeability is a broad term used to define the ability of the soil for transmitting water. It is important to understand the water dynamics and the water balance of the soil and it must be known for accurate management of Irrigation . It is determined partly by texture, with sandy soils having high permeability as compared to clay soils and it can be altered by soil management .
Soil structure refers to the arrangement of soil separates into units called soil aggregates. An aggregate possesses solids and pore space. Aggregates are separated by planes of weakness and are dominated by clay particles. Silt and fine sand particles may also be part of an aggregate
There are 5 basic types of structural units:
- Platy: Plate-like aggregates that form parallel to the horizons like pages in a book.
- This type of structure may reduce air, water and root movement.
- common structure in an E horizon and usually not seen in other horizons.
- Blocky: Two types–angular blocky and subangular blocky
- These types of structures are commonly seen in the B horizon.
- Angular is cube-like with sharp corners while subangular blocky has rounded corners.
- Prismatic: Vertical axis is longer than the horizontal axis. If the top is flat, it is referred to as prismatic.If the top is rounded, it is called columnar.
- Granular: Peds are round and pourous, spheroidal. This is usually the structure of A horizons.
- Structureless: No observable aggregation or structural units.
- Single grain-sand
- Massive-solid mass without aggregates
Chemical Properties
Nutrient availability and cation exchange capacity
In the soil, a large portion of plant nutrients are bound up in complex compounds that are unavailable to plants. The smaller portion is in simpler, more soluble forms, which are useable by plants. The complex compounds are gradually changed into the simpler compounds by Chemical Weathering and biological processes. Thus, the chemical fertility of a soil depends in part on how easily the plants can access the nutrients in a form they require. This is referred to as the availability of a nutrient. The availability of nutrients within the soil is also dependent on a range of factors such as soil pH, soil solution, soil type and the plant age, type and root system of the plant.
The pH value of the soil layers which will later make up the dikes and the bottom of your ponds will greatly influence their productivity. In acid water, for example, the growth of microscopic organisms which serve as food for the fish may be greatly reduced. In extreme conditions of acidity or alkalinity, the Health of your fish may even be endangered, and their growth and Reproduction affected.
For good productive conditions, the pH value of pond soil should be neither too acid nor too alkaline. Preferably, it should be in the range of pH 6.5 to 8.5. Soils with a pH value lower than 5.5 are too acid and soils with a pH value greater than 9.5 are too alkaline. They will both require special management techniques which will considerably increase the costs of fish production. If the soil pH is either lower than 4 or higher than 11, it should be considered unsuitable for the construction of pond dikes or for use as pond bottom.
Biological Properties
Soils host a complex web of organisms which can influence soil evolution and specific soil physical and chemical properties. For instance earth- worms activity increases infiltration rate, or microbial activity decreases soil organic matter due to mineralization. Soil biology plays a vital role in determining many soil characteristics, yet, being a relatively new science, much remains unknown about soil biology and about how the nature of soil is affected. Soil organisms break down organic matter and while doing so make nutrients available for uptake by plants. The nutrients stored in the bodies of soil organisms prevent nutrient loss by leaching. Microbes also maintain soil structure while earthworms are important in bio-turbation in the soil.
Organic matter in the soil improves soil structure and increasing the nutrient and water holding capacity of the soil. Organic matter also provides a food supply for soil biology. Soils with low organic matter can have ‘poor’ structure, hold little water, and erode or leach nutrients easily. The exception is cracking clay soils where clay Minerals have the main effect on structure. Soils with high organic matter levels have ‘good’ structure, good water-holding capacity, and reduced erosion and nutrient leaching.
,
Soil is a complex and dynamic system that is essential for life on Earth. It provides a medium for plant growth, helps to regulate the Climate, and filters and stores water. Soil is made up of four main components: minerals, organic matter, water, and air. The physical, chemical, and biological properties of soil are all important for plant growth and soil health.
Physical properties
The physical properties of soil include texture, structure, porosity, bulk density, water holding capacity, aeration, and temperature.
- Texture is the relative proportions of sand, silt, and clay particles in soil. Sand particles are the largest, followed by silt and clay. The texture of soil affects its ability to hold water and nutrients, as well as its drainage and aeration.
- Structure is the arrangement of soil particles into aggregates. Soil structure can be described as granular, blocky, prismatic, or crumbly. The structure of soil affects its water holding capacity, aeration, and drainage.
- Porosity is the amount of empty space in soil. Porosity is important for water infiltration, drainage, and aeration.
- Bulk density is the mass of soil per unit volume. Bulk density is affected by soil texture, structure, and organic matter content. High bulk density can make soil difficult to work and can reduce water infiltration and drainage.
- Water holding capacity is the amount of water that soil can hold against gravity. Water holding capacity is affected by soil texture, structure, and organic matter content. High water holding capacity is important for plant growth.
- Aeration is the movement of air through soil. Aeration is important for root Respiration and the decomposition of organic matter.
- Temperature is the Average temperature of soil. Temperature affects the activity of soil organisms and the growth of plants.
Chemical properties
The chemical properties of soil include pH, organic matter, nutrients, salinity, and heavy metals.
- pH is a measure of the acidity or alkalinity of soil. The pH scale ranges from 0 to 14, with 7 being neutral. Soils with a pH below 7 are acidic, while soils with a pH above 7 are alkaline. The pH of soil affects the availability of nutrients to plants.
- Organic matter is the dead remains of plants and animals. Organic matter helps to improve soil structure, water holding capacity, and nutrient cycling.
- Nutrients are essential for plant growth. The three main nutrients required by plants are nitrogen, phosphorus, and potassium. Other important nutrients include calcium, magnesium, sulfur, iron, manganese, copper, zinc, boron, molybdenum, and chlorine.
- Salinity is the amount of salt in soil. Salinity can affect plant growth by reducing the availability of water and nutrients.
- Heavy metals are metals that are toxic to plants and animals in high concentrations. Heavy metals can be found in soil due to natural processes or human activities such as mining and Industry.
Biological properties
The biological properties of soil include soil organisms, soil microbial activity, soil respiration, soil ENZYMES, and soil nutrient cycling.
- Soil organisms include bacteria, Fungi, algae, protozoa, nematodes, earthworms, and insects. Soil organisms play an important role in the decomposition of organic matter, the cycling of nutrients, and the control of pests.
- Soil microbial activity is the metabolic activity of soil organisms. Soil microbial activity is important for the decomposition of organic matter, the cycling of nutrients, and the production of soil humus.
- Soil respiration is the release of carbon dioxide from soil by soil organisms. Soil respiration is an important component of the carbon cycle.
- Soil enzymes are proteins that catalyze chemical reactions in soil. Soil enzymes are important for the decomposition of organic matter, the cycling of nutrients, and the plant growth.
- Soil nutrient cycling is the movement of nutrients through the soil, plants, and animals. Soil nutrient cycling is important for the maintenance of Soil fertility.
The physical, chemical, and biological properties of soil are all important for plant growth and soil health. By understanding these properties, we can better manage our soils to ensure their long-term productivity.
What is soil?
Soil is a mixture of minerals, organic matter, water, air, and living organisms. It is the foundation of life on Earth, providing plants with the nutrients they need to grow. Soil also helps to regulate the climate, filter water, and protect against erosion.
What are the different Types of Soil?
There are many different types of soil, each with its own unique characteristics. Some of the most common types of soil include:
- Sandy soil: Sandy soil is loose and well-drained, but it does not hold water or nutrients well.
- Clay soil: Clay soil is dense and holds water and nutrients well, but it can be difficult to work with.
- Loam soil: Loam soil is a mixture of sand, clay, and organic matter. It is the most fertile type of soil and is ideal for growing most plants.
What are the physical properties of soil?
The physical properties of soil include texture, structure, and porosity.
- Texture refers to the size of the particles in the soil. Soils can be classified as sandy, loamy, or clayey based on the Percentage of sand, silt, and clay particles they contain.
- Structure refers to the way the soil particles are arranged. Soils with good structure have a crumbly texture and are well-drained.
- Porosity refers to the amount of air and water that can be held in the soil. Soils with good porosity are well-drained and have good aeration.
What are the chemical properties of soil?
The chemical properties of soil include pH, organic matter content, and nutrient content.
- pH is a measure of how acidic or alkaline the soil is. Most plants prefer a pH between 6 and 7.
- Organic matter is the decaying remains of plants and animals. It helps to improve soil structure, fertility, and water retention.
- Nutrients are essential for plant growth. The most important nutrients for plants are nitrogen, phosphorus, and potassium.
What are the biological properties of soil?
The biological properties of soil include the number and types of organisms that live in the soil. Soil organisms include bacteria, fungi, nematodes, earthworms, and insects. These organisms play an important role in the cycling of nutrients and the decomposition of organic matter.
What are the benefits of healthy soil?
Healthy soil provides many benefits, including:
- It supports plant growth.
- It helps to regulate the climate.
- It filters water.
- It protects against erosion.
- It provides habitat for wildlife.
What are the threats to healthy soil?
The main threats to healthy soil are:
- Soil erosion: Soil erosion is the removal of soil from the land by wind or water. It can be caused by human activities such as deforestation, agriculture, and mining.
- Soil contamination: Soil contamination is the presence of harmful chemicals in the soil. It can be caused by industrial activities, agricultural practices, and improper waste disposal.
- Soil compaction: Soil compaction is the squeezing of soil particles together, which makes it difficult for water and air to penetrate the soil. It can be caused by heavy machinery, Livestock, and foot traffic.
What can be done to protect healthy soil?
There are many things that can be done to protect healthy soil, including:
- Reduce soil erosion: Soil erosion can be reduced by planting trees and shrubs, using cover crops, and practicing conservation Tillage.
- Reduce soil contamination: Soil contamination can be reduced by using safe disposal practices for hazardous waste, implementing pollution prevention measures, and cleaning up contaminated sites.
- Reduce soil compaction: Soil compaction can be reduced by using Light machinery, rotating livestock grazing areas, and planting deep-rooted plants.
- Improve soil health: Soil health can be improved by adding organic matter to the soil, rotating crops, and practicing no-till farming.
Soil is a mixture of four main components:
(a) mineral particles, organic matter, water, and air
(b) water, air, organic matter, and minerals
(c) minerals, organic matter, water, and air
(d) air, water, minerals, and organic matterThe mineral particles in soil are made up of:
(a) sand, silt, and clay
(b) sand, gravel, and clay
(c) sand, silt, and gravel
(d) gravel, sand, and clayThe organic matter in soil is made up of:
(a) plant and animal remains
(b) plant and animal waste
(c) plant and animal products
(d) plant and animal byproductsThe water in soil is important for:
(a) supporting plant growth
(b) providing nutrients to plants
(c) transporting nutrients to plants
(d) all of the aboveThe air in soil is important for:
(a) supporting plant growth
(b) providing Oxygen to plants
(c) providing carbon dioxide to plants
(d) all of the aboveThe physical properties of soil include:
(a) texture, structure, and drainage
(b) color, texture, and structure
(c) color, drainage, and structure
(d) texture, drainage, and colorThe chemical properties of soil include:
(a) pH, fertility, and salinity
(b) pH, salinity, and alkalinity
(c) pH, alkalinity, and fertility
(d) pH, fertility, and alkalinityThe biological properties of soil include:
(a) microbial activity, earthworm activity, and root activity
(b) microbial activity, earthworm activity, and plant activity
(c) microbial activity, plant activity, and root activity
(d) earthworm activity, plant activity, and root activitySoil erosion is the process of:
(a) the removal of soil from the land by wind or water
(b) the deposition of soil on the land by wind or water
(c) the movement of soil from one place to another by wind or water
(d) the mixing of soil with other materials by wind or waterSoil conservation is the practice of:
(a) preventing soil erosion
(b) restoring eroded soil
(c) both preventing soil erosion and restoring eroded soil
(d) neither preventing soil erosion nor restoring eroded soil