What is Soil?
Soils are a complex combination of organic matter, gasses, minerals, organisms, and liquids, that altogether support our life. Earth's body of soil is called the pedosphere, which has four important functions. It is a medium for plant growth, it stores water, supplies, and purifies, it is a modifier of the earth's atmosphere, it is a habitat for organisms. Soil is one of the principal substrata of life on earth, which is a participant in the cycling of carbon and other elements through the global ecosystem. To study the texture of soil samples and a few more go through the experiment below.
Soils are a complex combination of various organic matter, gasses, minerals, organisms, and liquids, all of which support our life. The Earth's body of soil is known as the pedosphere, which has four important functions:
Soil is used for the growth of plants. Soil helps to store water. Soil is said to be the modifier of the earth's atmosphere and also is a habitat for organisms.
To study soil samples from two different sites and in order to analyze their properties like the texture, moisture content, water-retaining capacity, and pH of the soil, the soil collected from the roadside is to be used. Apart from the soil samples, the following materials and apparatus are also needed:
Tile.
Beaker.
Funnel.
Burner.
Dropper.
Crucibles.
Petri dish.
Glass rods.
Test tubes.
Wire gauze.
Filter Paper.
Distilled water.
Mortar and Pestle.
pH paper booklet.
Measuring cylinder.
Universal pH indicator solution.
Tin Box with a perforated bottom.
Weighing scale or Electronic balance.
An Experiment to Study the Texture of Soil Samples
Aim:
To study the texture of soil samples,
To study the moisture content of the soil samples,
To study the capacity of holding water of soil samples,
To study the pH of the soil samples.
Apparatus Required:
Roadside and garden soil to be used. Other materials apart from the samples are:
Dropper
Beaker
Tile
Measuring cylinder
Filter paper
pH paper booklet
Test tubes
Distilled water
Funnel
Universal pH indicator solution
Wire gauze
Burner
Crucibles
Weighing scale
Mortar and pestle
Petri dish
Glass rods
Tin box with perforated bottom
Procedure:
The steps to analyze various properties:
To Study the Texture of Soil Samples,
Collect 50 gm of soil in a cylinder.
Pour a little water into the cylinder and shake.
Wait for the particles to settle down.
The particles in the measuring cylinder will start settling down in layers. Record the thickness of these layers.
To Study the Moisture Content of the Soil Samples,
Put the two samples of soil in different crucibles.
Weight the samples using a weighing balance.
Place the crucibles over the Bunsen burner and heat it until it becomes dry.
Weight the crucibles and record the weight of the dry soil samples.
The samples are now ready to be used to determine the moisture content of the soil.
To Study the Holding Capacity of Water of Soil Samples,
Take a soil sample in a mortar.
Grind it into a fine powder.
Place a filter paper at the bottom of the box.
Weigh the entire contents of the tin box and add the powdered soil into the box.
Use the glass rod to press and tap the box so that the soil is uniformly layered.
Measure and record the weight of the tin box.
Take two glass rods placing them parallel to each other. Ensure that the distance between the two is not significant.
Position the tin on the two glass rods such that the bottom is in contact with the water.
This setup should be left undisturbed until the water seeps through the upper surface of the soil.
Remove the tin and allow all the water to flow out from the bottom.
Wait until no more water percolates from the tin. Then, wipe the bottom dry and note down the weight using the weighing machine.
To Study the pH of the Soil Samples,
Take the roadside soil and put it into a beaker containing water. Repeat the steps for the garden soil sample as well.
Take a test tube and pour the soil solutions separately through filter papers using a funnel.
The collected filtrates in the test tube are ready for pH testing.
Put a few drops of universal indicator solution using a dropper in the test tube.
Finally, observe the changes.
Observation:
To Study the Moisture Content of the Soil Samples: The sample where the initial and final weight is the larger indicated higher moisture content and if lower indicates the lower moisture.
To Study the pH of the Soil Samples: The color changes are trackable using the pH color chart. Roadside soil has a pH level of 7 while garden soil has a pH level of 6. Maximum crops grow between pH levels of 6.0 and 7.0.
Solved Examples
Question: What are the layers of soil?
Answer: The layers of soil are topsoil, subsoil, and parent rock.
Fun Facts
It contains more organisms in one tablespoon of soil than there are people on earth.
Even to form an inch of topsoil it may take nearly 500 years.
0.01 percent of the water on earth is held in the soil.
Soil lies at the bottom of the food chain. Still, it is the cornerstone of life on the earth.
FAQs on Collect and Study Soil from at Least Two Different Sites
1. What is the main objective of collecting and studying soil from two different sites?
The primary objective is to understand that soil is not uniform. By comparing samples from different locations, such as a garden and a roadside, students can observe and analyse variations in key properties like texture, colour, moisture content, and pH. This experiment highlights how environmental factors and human activity directly influence soil composition and overall health.
2. What are the key physical properties to observe when comparing soil samples?
When comparing different soil samples, several key physical properties should be noted:
- Texture: The feel of the soil, which indicates the proportion of sand, silt, and clay. It can be described as gritty, smooth, or sticky.
- Colour: The soil's colour, such as dark brown, red, or light grey, which provides clues about its mineral content and the amount of organic matter (humus).
- Moisture Content: The quantity of water held within the soil sample, which is essential for plant life.
- Water-Holding Capacity: The ability of the soil to retain water after being saturated, which varies greatly between soil types.
3. How is the pH of a soil sample tested and what does it indicate about its health?
To test the pH of a soil sample, it is typically mixed with distilled water, and then a universal indicator solution or pH paper is used to measure its acidity or alkalinity. The pH value is crucial as it indicates the soil’s chemical health. Most plants thrive in a neutral pH range of 6.0 to 7.5. A pH level outside this range can lock up essential nutrients, making them unavailable to plants and hindering their growth.
4. What is the water-holding capacity of soil, and why does it differ between sandy and clay soils?
The water-holding capacity is a measure of a soil's ability to retain water against the pull of gravity. This property differs significantly based on soil texture. Clay soil, composed of very fine particles, has a high water-holding capacity because the small pore spaces between particles hold water tightly. In contrast, sandy soil has large particles with large gaps, which allows water to drain through quickly, resulting in a very low water-holding capacity.
5. Why might soil from a roadside and a garden show different textures and pH levels?
Soil from a roadside and a garden often exhibits major differences due to their distinct environments. Roadside soil is typically more compacted due to traffic and may have a higher pH from alkaline construction debris. It also tends to be grittier from accumulated dust. In contrast, garden soil is usually rich in organic matter (humus), making it darker, more aerated, and often slightly acidic—a condition that is ideal for the growth of most plants.
6. How does the presence of living organisms, like earthworms, affect the properties of a soil sample?
Living organisms, particularly earthworms, are vital for soil health. Their burrowing activity aerates the soil, which improves water drainage and allows plant roots to penetrate more easily. Furthermore, as earthworms consume organic matter, their castings (excrement) enrich the soil with essential nutrients, significantly boosting its fertility. The presence of a healthy earthworm population is a strong indicator of a thriving soil ecosystem.
7. If a farmer discovers their soil is too acidic (low pH), what can be done to improve it for better crop growth?
If a farmer's soil is found to be too acidic for their crops, they can apply alkaline substances to neutralise it. The most common agricultural practice is liming, which involves adding powdered limestone (calcium carbonate) or dolomite to the soil. This process raises the soil pH to a more neutral level, which in turn improves the availability of crucial nutrients for the plants, leading to better growth and yield.
8. Besides pH and moisture, what other factors are crucial for determining soil fertility?
Beyond pH and moisture, soil fertility is determined by several other critical factors. These include the nutrient content (especially levels of nitrogen, phosphorus, and potassium), the amount of organic matter or humus which improves soil structure, and the presence of a diverse community of soil microorganisms. These microbes are essential for decomposing organic material and converting nutrients into forms that plants can absorb.
