Properties of Soil, Agriculture and Water Availability Impacts Laboratory

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Question Description

Properties of Soil, Agriculture and Water Availability Impacts Laboratory

This lab enables you to analyze the natural porosity and particle size of soil samples along with the chemical composition and profile of different soil types.

The Process:

Take the required photos and complete all parts of the assignment (calculations, data tables, etc.). On the “Lab Worksheet,” answer all of the questions in the “Lab Questions” section. Finally, transfer all of your answers and visual elements from the “Lab Worksheet” into the “Lab Report.” You will submit both the “Lab Report” and the “Lab Worksheet” to Waypoint.

The Assignment:

Make sure to complete all of the following items before submission:

Carefully review the Grading Rubric (Links to an external site.)Links to an external site. for the criteria that will be used to evaluate your assignment.

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ENVIRONMENTAL SCIENCE Properties of Soil: Agricultural and Water Availability Impacts Investigation Manual PROPERTIES OF SOIL: AGRICULTURAL AND WATER AVAILABILITY IMPACTS Table of Contents 2 Overview 2 Outcomes 2 Time Requirements 3 Background 10 Materials 11 Safety 11 Preparation 12 Activity 1 13 Activity 2 14 Activity 3 15 Submission 15 Disposal and Cleanup 16 Lab Worksheet 18 Lab Questions Overview Earth’s soil plays a major role in the world’s agriculture and has a substantial effect on water availability in a given area. In this investigation, students will analyze the natural porosity and particle size of soil samples along with the chemical composition and profile of different soil types. Outcomes • Examine the properties of soil and their effects on agriculture and water availability. • Describe and identify soil horizons based on their chemical and physical composition. • Distinguish between the particle sizes of three different types of soil: sand, silt, and clay. • Determine the porosity of different soil types. • Analyze soil samples for a variety of nutrients to determine soil fertility. Time Requirements Preparation ....................................................................... 5 minutes Activity 1: Particle Size Distribution and Determination of Soil Texture Day 1 ...................... 20 minutes, then let sit for 24 hours Day 2 ............................................................. 30 minutes Activity 2: Porosity of Different Soil Types ...................... 60 minutes Activity 3: pH Test Comparison of Soil Samples ............ 30 minutes Activity 4: Nitrogen, Phosphorus, and Potash Test Comparisons of Soil Samples Day 1 ...................... 20 minutes, then let sit for 24 hours Day 2 ............................................................. 60 minutes Key Personal protective equipment (PPE) goggles gloves apron Made ADA compliant by NetCentric Technologies using the CommonLook® software 2 Carolina Distance Learning follow link to video photograph stopwatch results and required submit warning corrosion flammable toxic environment health hazard Background Soil Horizons and Chemical Composition The type of dirt that makes up the dry surfaces of the earth has numerous effects on humans and the environment, and vice versa. Humans can modify the suitability of some areas for agriculture based on prior land use. The properties of soil also determine water availability in a given area. Areas that contain the most suitable soil for farming are often limited. Certain properties of soil determine whether an area is suitable for human activity. When considering the properties of soil, its texture, shape, particle aggregation, and suitability for growth come to mind. These properties all play a major role in determining the capability of an area to retain water and air, which are necessary for several agricultural processes that are vital to human life. It is important to understand the profile and chemical composition of soil to understand how they affect agriculture and water availability. For instance, some farmlands have been plowed for hundreds of years yet the soil has remained very fertile. However, in other areas with a similar history, much of the soil has been adversely affected (over one-third of the soil in the United States is now deemed as destroyed). With years of continuously turning over the soil to cultivate crops, the damage accumulates and many areas are left vulnerable to erosion, weathering, and deterioration of nutrient and organic material. Why then is there such great disparity in the way certain soils flourish? It is because of the various layers, or horizons, of the soil. Soils differ greatly depending on the proportion of each of these horizons (see Figure 1). If you were to dig a hole or drive a corer (a special drill that uses a hollow steel tube to remove a cylindrical dirt sample) deep into the ground to extract a sample of soil, a visible color difference would be evident in the soil profile, or horizon composition. The colors of the various horizons differ based on the organic content and mineral composition of each soil. Each horizon can also vary in texture, which is determined by the makeup of sand, silt, or clay. Figure 1. As shown in Figure 1: • The O-horizon is the most nutrient-rich part of the soil profile, mainly because of its abundance in organic matter. This layer is often referred to as the humus layer and is usually dark brown or black in color. continued on next page 3 PROPERTIES OF SOIL: AGRICULTURAL AND WATER AVAILABILITY IMPACTS Background continued • The A-horizon, also known as topsoil, is the next layer down. This layer contains some organic matter in addition to a mixture of minerals. This horizon tends to be lighter black to brown in color. • Further down is the B-horizon, or the subsoil. Much of the soil in this region has undergone some degree of weathering and is composed almost entirely of mineral material. Its high iron and clay content usually imparts a reddish color. • The C-horizon is generally composed of weathered rock fragments and material from the layers above. • The lowest region is known as the R-layer (sometimes referred to as the D-horizon), which mostly consists of unaltered bedrock material. It is important to note that all these layers are not necessarily present in every soil profile and the proportions of each layer can vary drastically among various soil samples. Thus, with the farmland example earlier, much of the fertile soil may have had thicker O- and A-horizons, making it more suitable for agriculture even after many years, whereas the damaged soil may have had much thinner top layers. The ages of these soils may make a considerable difference as well. Older soils tend to have almost all horizons present, and younger soils tend to have far fewer horizons. Identifying Soil Types: Texture and Structure In addition to distinguishing the chemical and biological makeup of soil, it is also important to understand the impact of soil on water availability in a given area. Particle size is 4 Carolina Distance Learning one of the most important aspects of soil type descriptions that helps to determine the holding capacity of the soil as well as its ability to filter water. The size of soil particles determines the soil’s texture, which can be classified into smaller subcategories (primary units) depending on the mineral components of the soil. Texture is determined by the ratio of sand, silt, and clay in the soil sample (see Table 1). Table 1. Soil Type Particle Size Sand Particles with a diameter greater than 0.05 mm Silt Particles with a diameter between 0.002 and 0.05 mm Clay Particles with a diameter less than 0.002 mm Every soil sample will have different proportions of these primary units. Based on these proportions, each soil sample can be further categorized and identified. Figure 2 shows a soil analysis chart that illustrates the different classes of soil based on their combinations of sand, silt, and clay. Loam is a close-to-equal mixture of these three primary units and can be used to identify multiple soil types. Determining particle size (based on these subcategories of soil texture) is the first step in soil characterization. The next step is determining the structure of the soil, which defines how the individual particles aggregate. continued on next page The soil structure affects how easily air, water, and the roots of plants are able to move within the soil. The arrangement of soil particle aggregates can be broken down into peds, or secondary units of the primary soil particles— sand, silt, and clay. Knowing the type of soil present by first identifying the primary and secondary particle types can help determine whether the soil is suitable for agriculture. Soil permeability (ability of water to flow through a soil) is directly related to the particle size (texture) and the aggregation of those particles (structure) (see Figure 3). Rounded, granular peds are particularly suitable for plant growth because their structure easily permits penetration by air, water, and roots. Clay Figure 2. continued on next page 5 PROPERTIES OF SOIL: AGRICULTURAL AND WATER AVAILABILITY IMPACTS Background continued and loamy soils often have blocky peds that are angular and somewhat irregular in shape and permit the flow of air and water. In platy peds, however, some passageways are blocked because the soil particles are tightly packed. A platy soil usually has high clay content and often occurs in areas that are frequently flooded. These classifications are not applicable to sand because of its inability to form aggregates; thus, instead of clumping, it falls apart. The roots of plants require air and water. Just as a plant can die from lack of water, it can also die in waterlogged soil owing to a lack of air. Soil must retain water and permit root penetration to support plant life. However, certain particle sizes and arrangements of particles allows for permeability conditions that could be detrimental to agriculture. Therefore, particle size and arrangement need to be identified to determine proper soil usage. Porosity is defined as the amount of void space between individual soil particles. With high porosity between particles, a greater volume of water can permeate but might also waterlog certain systems. Porosity is another major property of soil that has a significant effect on water infiltration and soil fertility, or the ability of soil to hold sufficient nutrients for plant growth. In the following section, nutrient availability and chemical composition—and their effects on different soil types—are discussed. Granular Processes Affecting the Fertility of Soil Determining the productivity of the soil in a given area is crucial. The pH value, or the number of hydrogen ions present in the soil, is a major indicator of soil fertility. The pH scale ranges from 0 to 14, with a value of 7 being neutral. Anything less than 7 is acidic, and anything more than 7 is considered basic. This scale is logarithmic, so if a solution has a pH of 6, it has ten times the number of hydrogen ions (or is ten times more acidic) than a solution with a pH of 7 possesses. There are wide ranges of pH for a variety of soils; for example, quartz-rich sandstone is rather acidic, whereas limestone tends to be basic. Columnar Rainwater, which has a pH of approximately 5.5, has a significant impact on soil pH. The low pH of rainwater is caused by the mixing of water with carbon dioxide in the atmosphere. Carbonic acid is formed when the precipitation Figure 3. Platy Blocky continued on next page 6 Carolina Distance Learning makes contact with the earth’s surface. As this rainwater flows into and along soil surfaces, it transmits many nutrients into the depths of the soil. Iron, along with other minerals such as calcium and magnesium, tends to flow through the higher horizons, which are usually flourishing with life, and continues into the lower horizons that tend to be lacking in nutrients. Besides pH, decomposition is another important factor in determining the health of soil. Organisms such as bacteria and fungi decompose (break down) organic matter that plants and animals produce at the surface and deposit into the soil, allowing for the survival of organisms deeper in the soil. The rate of decomposition can be increased by worms and Figure 4. other organisms living near the surface. These organisms break down detritus (debris and waste) into smaller bits that sink farther into the soil, feeding the bacteria and fungi. Nutrients are essential for plant growth. One major issue regarding the health of certain soil types in some areas is the inability of the soil to retain sufficient nutrients. Adding fertilizers and pesticides helps replenish crops and soil, but an excess of these nutrients can also exert negative effects. Macronutrients are nutrients needed at high concentrations by all living things. Nitrogen, potassium, phosphate, and magnesium are examples of these nutrients necessary for plant growth. Micronutrients—such as the metals zinc, iron, and copper—are those needed in smaller quantities. Fertilizers are useful to replace macronutrients lost from the soil. Many fertilizers, such as manure, are either purely or mostly organic matter; however, numerous synthetic fertilizers have also been developed. Nitrogen, phosphorous, and potassium are commonly regarded as the limiting nutrients in crop production and are therefore typically added to soils in specific amounts via fertilizers. Nitrogen is a special case; plants require nitrogen in the form of ammonium or nitrate, and atmospheric nitrogen can only be converted synthetically, or by soil-dwelling microbes, as part of the nitrogen cycle (see Figure 4). continued on next page 7 PROPERTIES OF SOIL: AGRICULTURAL AND WATER AVAILABILITY IMPACTS Background continued Additional ways in which nitrogen can enter the soil include via the death and decomposition of plants and by the production of nitrogenous waste from plants being eaten by animals. Nitrogen is vital for plant growth; it is a very important structural component of chlorophyll, the compound used by plants in photosynthesis to produce oxygen and sugars. Nitrogen is also a major component of amino acids, which are the building blocks of proteins. Since it is not retained by soil, excess nitrogen can leach onto the surface or into groundwater, causing algal blooms and a loss of oxygen. Although nitrogen is an essential element, because it is not retained by the soil, farmers frequently need to reapply fertilizers containing nitrates, which in turn can lead to environmental challenges. Phosphorus is usually present in the form of phosphates in the soil. Phosphate is an important component of adenosine triphosphate/adenosine diphosphate (ATP/ADP) in plants and is therefore necessary for energy transport and storage. Phosphates, along with pentose sugars, make up the backbone of DNA and RNA. Phosphorus availability frequently limits plant growth and flowering; therefore, the introduction of phosphates into soil can lead to rapid plant growth. This element also plays a major role in keeping the root systems of plants strong and thriving. However, like excess nitrates, too much phosphorus can lead to algal blooms, which can harm aquatic ecosystems (see details of the phosphorus cycle in Figure 5). The last main nutrient in fertilizer is known as potash. It is a mixture of various salts that contain soluble potassium, which is vital for the development of many flowers and fruits. Potassium is required for the activation of numerous enzymes and for the regulation of pH as well. It also controls the opening and closing of the stomata (pores in the leaves), which affects photosynthesis, water and gas transport, and temperature regulation. In this investigation, you will conduct experiments to determine the texture and structure of soil samples as well as the ability of water to permeate each sample. You will also perform chemical tests to determine the fertility of two soil samples. continued on next page 8 Carolina Distance Learning Figure 5. 9 PROPERTIES OF SOIL: AGRICULTURAL AND WATER AVAILABILITY IMPACTS Materials Needed from the equipment kit: Included in the materials kit: Bag of clay, ½c rapitest® Soil Tester kit 3 Plastic tubes 6 Twist ties 3 Rubber bands 5 Test tubes Test tube rack Permanent marker Cheesecloth 2 Pipets Ruler Plastic cup Needed from the Groundwater and Surface Water Interactions investigation materials kit: • 2 small handfuls of sand from the large bag of sand Graduated cylinder, 100 mL Graduated cylinder, 10 mL Needed but not supplied: • Sheet of white paper • • 2 Soil samples • • Distilled water • Tap water • • Liquid hand soap • Tool for digging soil (trowel, large spoon, etc.) 10 Scissors Stopwatch (or cell phone with a timer) Camera (or cell phone capable of taking photographs) Carolina Distance Learning Reorder Information: Replacement supplies for the Properties of Soil: Agricultural and Water Availability Impacts investigation can be ordered from Carolina Biological Supply Company, item number 580822. Call: 800-334-5551 to order. Safety Wear your safety goggles, gloves, and lab apron for the duration of this investigation. Read all the instructions for these laboratory activities before beginning. Follow the instructions closely, and observe established laboratory safety practices, including the use of appropriate personal protective equipment (PPE). Avoid contact with skin, eyes, and mouth when working with rapitest® Soil Tester capsules. Wear PPE at all times when using these capsules. Wash your hands immediately following the use of these capsules. Do not eat, drink, or chew gum while performing these activities. Wash your hands with soap and water before and after performing each activity. Clean the work area with soap and water after completing the investigation. Keep pets and children away from lab materials and equipment. Preparation 1. Read through the activities. 2. Obtain all materials. 3. Identify a location where you can easily collect a small amount of soil out of the ground (e.g., at the edge of your yard or at a nearby park). 4. Using your digging tool, collect a few handfuls of soil from about 3 inches below the surface and place it in a plastic cup from the equipment kit. (There should be enough to fill the cup approximately halfway.) This sample will be known as “Soil Sample A” and will be used in all the activities. Before using the sample, remove excess grasses, roots, and other plant materials and break up any large clumps. 11 ACTIVITY ACTIVITY 1 Particle Size Distribution and Determination of Soil Texture Day 1 1. Take three test tubes from the equipment kit and label them “Sand,” “Clay,” and “Soil Sample A” (one for each sample). 2. Fill each vial halfway with its designated soil sample. For each test tube, add tap water to about 1 cm below the top. Then add one drop of liquid hand soap to each sample (this helps settle the particles). 3. With gloved hands for each test tube, place your thumb over the opening. Shake each test tube for 30 seconds. Allow the samples to settle overnight in the test tube rack. Place a piece of paper over the top of the three test tubes to prevent contamination of the samples. 3. Use a ruler to measure the thickness (in centimeters) of the sand, silt, and clay layers in “Soil Sample A.” The silt layer is the layer formed between the clay and sand layers, owing to its particle size that is larger than that of clay but smaller than that of sand (see Figure 6). Record these values in Data Table 1 of the “Observations/Data Tables” section of the Lab Worksheet. All layers may not be visible or may vary substantially in depth in “Soil Sample A.” 4. Measure the total depth of the soil. Be careful to exclude the humus layer containing floating dirt and grasses at the top of the sample (see Figure 6). Record the total depth in Data Table 1 of the “Observations/Data Tables” section of the Lab Worksheet. Figure 6. 4. Hypothesize what percentages of sand, silt, and clay you expect to find in “Soil Sample A.” Remember: your percentages must add up to 100%. Record your hypothesis in the “Hypotheses” section of the Lab Worksheet. Day 2 1. Place a sheet of white paper behind the test tubes containing the settled soil samples, and observe the layers that have formed in each. Take a photograph of the three samples with the paper behind them, and upload it to the “Photographs” section of t ...
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Tutor Answer

School: UT Austin





Properties of Soil
SCI 207: Our Dependence upon the Environment
Instructor’s Name


Properties of soil: Agricultural and Water Availability Impacts
It is important to know the topic of this lab because it gives clear directions on how to
analyze natural porosity and particle sizes of soil samples. In addition, the chemical composition
and soil types will be studied. Soil plays a crucial role in the world’s agriculture and also water
availability effect in an area due to its chemical compositions. Soil properties determine human
activities in a certain area as soil properties and texture is put into consideration (Ma, Du, Zhou
& Shen, 2018). Understanding the impact of soil on water is an important aspect in a given
locality. The sizes of particles will determine the type of soil descriptions so that it helps in
determining how long certain soil types can hold water.
The main purpose of this lab is to make an examination on soil properties and their
agricultural effects and water availability. Besides, describing and identifying the soli horizons
based on the chemical properties will be studied. In addition, we will be able to differentiate
between the particles sizes of sand, clay and loam soil. Finally, the porosity of and analysis of
different soil types will be determined.
Activity 1: The concentration of clay soil is low while silt is higher. The concentration of sand
soil in sample A is the highest. The percentages are 15, 25 and 60 respectively.
Activity 2: Clay soil has the highest porosity with 55%, while silt is medium, with 51%. Sandy
soil is the lowest with 40%. Coarse soil has the lowest porosity while fine soil has the highest



Activity 3: The sand soil tends to be more acidic unlike clay soil which is alkaline. Silt soils are
very fertile and recommended for farming. Sandy soils drain water very easily and also it can
warm quickly.
Activity 4: Clay has a higher nutrien...

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Thanks, good work

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