SOIL RESOURCES

Soil - Soil allows us to plant that helps us make the world more sustainable and soil plays important role in maintaining the cycle and balance of life on Earth

The Layers of Soil

Just how the Earth has its layers the soil that is part of our lithosphere also has its own layers.

- O Horizon (Organic Layer): This top layer consists mostly of organic matter, such as decomposed leaves, plants, and other organic material. It's rich in nutrients and is crucial for supporting plant life.

- A Horizon (Topsoil): Below the O horizon, the A horizon contains a mix of organic material and minerals. It is often dark in color due to the presence of organic matter and is vital for plant growth as it holds most of the soil's nutrients.

- E Horizon (Eluviation Layer): This layer is characterized by leaching, where minerals and nutrients are washed away by water. It typically appears lighter in color and has fewer nutrients compared to the A horizon.

- B Horizon (Subsoil): The B horizon accumulates minerals and nutrients that have leached down from the above layers. It often contains clay, iron, and other minerals, giving it a denser texture. This layer is crucial for storing nutrients that plants can access.

- C Horizon (Parent Material): This layer consists of weathered rock and mineral material that has not yet developed into soil. It serves as a source of minerals for the upper layers and can vary widely in composition.

- R Horizon (Bedrock): The deepest layer, this consists of solid rock that has not been weathered. It forms the foundation upon which the soil layers develop.

1. Biological Diversity:

A single tablespoon of soil can contain billions of microorganisms, including bacteria, fungi, and protozoa. This microbial community plays a crucial role in nutrient cycling and plant health.

2. Soil Erosion:

It’s estimated that about 24 billion tons of fertile soil are lost each year due to erosion, primarily from agricultural activities. This loss poses a significant threat to food security.

3. Carbon Storage:

Soil is a major carbon sink, storing more carbon than the atmosphere and all plant life combined. Healthy soils can help mitigate climate change by sequestering carbon dioxide.

SOIL HORIZONS

O - Organic Layer

Humus

A - Topsoil

Minerals with humus

E - Eluviation Layer

Leached minerals & organic matter

B - Subsoil

Deposited minerals & metal salts

C - Parent Rock

Partly weathered rock

R - Bedrock

Unweathered parent rock

Soil Moisture

Soil moisture refers to the amount of water present in the soil. It plays a crucial role in plant growth, as it influences water availability for roots, affects soil structure, and impacts various biological processes. Soil moisture can vary with factors like rainfall, temperature, and soil type, and it is typically measured in terms of volumetric water content or gravimetric water content. Monitoring soil moisture is important for agriculture, ecology, and managing water resources effectively.

Monitoring agriculture, predicting droughts and floods, predicting forest fires, managing the water supply, and other operations involving natural resources all depend on soil moisture. Observations of soil moisture can alert observers to circumstances of drought or flooding before other, more conventional signs are activated.

To make sure that farmed plants have access to enough water to stay healthy, irrigation adds water to the soil. Some soils will get wetter while others may become drier since this water needs to be moved, stored, and acquired from another place. Applying more water will increase evapotranspiration, which might result in less water being available downstream and change the energy and water fluxes between the atmosphere and the land surface, thereby influencing the local climate.

Soil Erosion

We frequently pay attention to the plants when we clean our lawns, drive by cornfields, or go on hikes in the woods: the green grass borders, the blooming flowers, and the stalks with tassels above them. But the dirt—what about that? It appears that one of the most undervalued natural resources on the earth is soil. However, good soil is not just the cornerstone of agriculture but also essential for safeguarding our climate, the food we eat, the water we drink, and the air we breathe.

The topsoil, or fertile layer of dirt that is essential to life, is eroded over time and is referred to as soil erosion. The composition of the soil, the amount of vegetation, and the strength of the wind and rain all affect how quickly soil erosion occurs. We possess both the ability and the obligation to address one of the world's most pressing environmental issues, as our actions can also impact the rate of soil erosion.

Soil is a natural substance that exists on the surface of the earth and is made up of solids (minerals and organic matter), liquids, and gases, soil is distinguished from its original material by one or more of the following: horizons, or layers, that are identifiable due to the additions, removals, transfers, and transformations of energy and matter; or the capacity to sustain rooted plants in their natural habitat.

The process of continuously forming and moving the topsoil due to various factors, particularly water, wind, and mass development, is known as soil erosion, and it eventually leads to the decomposition of the soil. To put it another way, tillage, wind, and water cause the top, most fertile layer of soil to be removed, which is known as soil disintegration.

A system of farming techniques known as "soil conservation" prevents soil erosion, deterioration, and depletion. Future-focused long-term use is the goal of soil conservation management. Farmers improve their fields' performance for years to come by acting appropriately and on time.

Soil texture refers to the relative proportions of sand, silt, and clay in a soil sample, significantly influencing its physical properties. Coarse-textured soils (sandy) typically drain quickly but retain less water, while fine-textured soils (clay) retain water but can become waterlogged. Understanding these properties is crucial for effective agricultural practices, as different crops require varying moisture levels. Ecosystems like forests, grasslands, and wetlands exhibit diverse soil textures shaped by climate, vegetation, and land use. Additionally, human activities such as construction and farming can compact or alter soil texture, affecting its natural functions and health.

Kinds of Soil and Their Characteristics:

Sand:

- Is the soil sandy or gritty? Yes

- Can it be moulded to form a ball? No

Loamy Sand:

- Is the soil sandy or gritty? Yes

- Can it be moulded to form a ball? Yes

- Does the ball of soil break up easily? Yes

Sandy loam:

- Is the soil sandy or gritty? Yes

- Can it be moulded to form a ball? Yes

- Does the ball of soil break up easily? No

- Does the soil feel smooth and silky? No

Sandy silt loam:

- Is the soil sandy or gritty? Yes

- Can it be moulded to form a ball? Yes

- Does the ball of soil break up easily? No

- Does the soil feel smooth and silky? Yes

Silt loam

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? Yes

Sandy clay foam

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? No

- When smeared between finger and thumb does the soil take a strong polish and is it hard to deform? No

- Does the soil feel sandy or gritty? Yes

Silty clay foam

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? No

- When smeared between finger and thumb does the soil take a strong polish and is it hard to deform? No

- Does the soil feel sandy or gritty? No

- Does the soil feel smooth and soapy? Yes

Clay foam

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? No

- When smeared between finger and thumb does the soil take a strong polish and is it hard to deform? No

- Does the soil feel sandy or gritty? No

- Does the soil feel smooth and soapy? No

Sandy Clay

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? No

- When smeared between finger and thumb does the soil take a strong polish and is it hard to deform? Yes

- Does the soil feel sandy or gritty? Yes

Silt Clay

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? No

- When smeared between finger and thumb does the soil take a strong polish and is it hard to deform? Yes

- Does the soil feel sandy or gritty? No

- Does the soil feel smooth and soapy? Yes

Clay

- Is the soil sandy or gritty? No

- When moulded into a ball, is it buttery and easily deformed? No

- When smeared between finger and thumb does the soil take a strong polish and is it hard to deform? Yes

- Does the soil feel sandy or gritty? No

- Does the soil feel smooth and soapy? No

Sandy:

• most porous (amount of air spaces in it) soil and has bigger particles

• allows water to drain easily warms very fast during season of spring

• easier to cultivate because of the organic material, nutrients, & moisture

Silty

• smooth to touch and very fertile

• retains water pretty well

• can hold more moisture w/c makes it much easier to work with

Clay

• have smallest or fine particles

• has greater water retaining capacity rich in mineral content

• becomes heavy when wet and difficult to cultivate

Loamy

• combination of silt, sand, clay, and a little humus

• very good for gardening

• retains water very easily

Horizons and their characteristics

1. O Horizon: This is the topmost layer, rich in organic material like decomposed leaves and plants.

Parent Material: The underlying geological material from which soil forms, impacting the soil's mineral content.

Human Activity: Farming, construction, and other activities that can alter the O horizon's composition.

2. A Horizon: Known as topsoil, this layer contains a mix of organic material with minerals and is critical for plant growth.

Time: The age of soil, affecting its development and nutrient composition.

Soil pH: A measure of acidity or alkalinity, which influences nutrient availability for plants.

3. B Horizon: Also called the subsoil, this layer accumulates minerals leached from the topsoil and has less organic material.

Climate: Temperature and precipitation that affect soil formation and nutrient cycling.

Soil Fertility: The ability of soil to support plant growth, impacted by nutrient levels in this layer.

4. C Horizon: This layer consists of weathered parent material and little organic matter, often serving as a transition to bedrock.

Biological Activity: The presence of microorganisms and roots, affecting soil structure and nutrient cycling.

Leaching: The process by which water carries minerals downward through soil layers, impacting nutrient distribution.

5. R Horizon: The bedrock layer, mostly unweathered, which influences the mineral content of the soil above.

Topography: The landscape shape, affecting water drainage, erosion, and soil depth.

Water Retention and Loss: Soil’s ability to hold water, essential for plant growth, varies with soil type and composition.

These factors collectively influence soil formation, fertility, and suitability for different types of vegetation.

Questions:

1. How does soil texture influence water retention and drainage? Soil texture is really important because it affects how water is held in the soil and how well it drains. For example, sandy soil has bigger particles, so water flows through it quickly, which means it doesn’t hold water well. On the other hand, clay soil has tiny particles that keep water tightly, but it doesn’t drain well, which can lead to puddles. Loamy soil is a mix of sand, silt, and clay, which helps it hold some water while still allowing drainage. So, knowing the texture helps us understand how water will behave in different soils.

2. Why is it important to understand soil texture when planning agricultural activities? It is important to understand soil texture when planning agricultural activities due to its management of nutrients in plants. A cycle of nutrients from the soil to plants helps maintain the nutrients essential required for the growth of the plant. Additionally the soil when it’s dry or wet also contributes to the growth of vegetation. For example, clay soil is is nutrient-dense but is difficult to cultivate due to its density when it is wet and hardness when its dry, and has poor draining. On the other hand, loamy soil is considered one of the best types of soil for agriculture due to its ability to hold moisture and plenty of nutrients efficiently, its high water retention and good drainage resulting in sufficient air reaching the roots.

3. How might soil texture vary in different ecosystems, and what environmental factors could cause these differences? Soil texture can vary across different ecosystems due to several environmental factors. In forests, the soil tends to be rich in organic matter and often has a loamy texture, which supports diverse plant life. In contrast, deserts typically have sandy soils that drain quickly and retain less moisture, making them less fertile. Climate plays a major role; areas with heavy rainfall can lead to more clay-rich soils due to leaching, while dry land regions have sandy soils. Vegetation also influences soil texture; plants contribute organic material that improves soil structure. Additionally, human activity like agriculture and urban development, can affect soil texture by compaction or adding different materials. In summary, the cooperation of climate, vegetation, and human impact shapes the soil texture of various ecosystems, resulting in distinct characteristics suited to each environment.

4. How can human activities (like farming or construction) alter soil texture over time?

Agriculture can lead to erosion, especially when there’s overgrazing and plowing that removes ground cover. Plowing up and down slopes can make erosion even worse compared to plowing along the slope. While soil texture doesn’t change easily, we can improve it over time by continuously adding organic matter like manures, tank silt, green manures, and leftover materials from crops like paddy roots and sugarcane trash. These practices can help change the surface soil’s structure, texture, and porosity, but they may not have much effect on the subsoil.

Agriculture also affects the natural cycle of nutrients in the soil. When we intensively cultivate and harvest crops for food, we can deplete the soil of essential nutrients. To keep the soil fertile and ensure good crop yields, we usually need to add soil amendments. On the other hand, construction projects can cause soil erosion too because they dig up the land and disturb the natural ground. While erosion happens slowly over time, construction speeds it up, which can lead to more serious issues.

Construction projects often have measures in place to prevent erosion, but these aren’t always 100% effective. To really protect the soil, we need to be careful about how we manage both agricultural practices and construction activities. By combining good farming methods with effective construction techniques, we can minimize erosion and help maintain healthy soil for the future.

5. The environment has grass and crops like calamansi, camias, and tomatoes, which shows that the soil is already supporting plant life. This means that the loamy sand soil can handle more planting. Loamy sand is known for draining well, which is good for plants that don’t need too much water. The fact that these crops are growing indicates that the soil is providing enough nutrients for them to thrive.

However, sandy soil like this doesn’t hold onto water and nutrients as well as other types of soil, which could be a problem for some plants. To improve this, adding organic matter like compost would really help. It can make the soil better at holding water and nutrients, which would benefit plants that need richer soil.

Overall, since we already see crops growing, the soil seems good for planting. But we could make it even better by adding some organic material. This would help support a wider variety of plants and promote healthier growth, ensuring that the soil remains productive in the long run.