Introduction: (Initial Observation)
How do you know if a soil is good for agriculture? or what elements need to be added to that to be good for farming. These are some of the question that millions of farmers from around the word are challenged with when they are planning purchase or take over a new land for agriculture. To find the answer they will have the soil tested by specialized laboratories. These tests will help the farmers to make the right decision and protect their investment.
My goal of this project is finding a way to quickly and efficiently test the soil for properties needed for agriculture.
Find out about the properties in soil that are important for growing plants. Read books, magazines or ask professionals who might know in order to learn about the methods that soil can be tested for such properties. Keep track of where you got your information from
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to find out how soil can be analyzed for it’s components and properties needed for agriculture.
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Variables that can affect fertility of soil are moisture, pH, organic matter and soluble minerals and salts. Each of these variables will have a different affect on the fertility of soil. In this project we will not test the fertility of the soil, but we try to analyze a soil sample to rate each variable.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
My hypothesis is that we can weight a soil sample and then let it dry. The weight loss will represent the amount of moisture. We can then burn the sample in high temperature to get rid of organic material. Weight loss at this stage represents the amount of organic mater. Ability to hold moisture must be tested on a dry sample. We can add water to the dry soil to see how much water will stay within the soil.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Collecting a Soil Sample
soil container, such as a coffee can with lid
flags or markers
Sorting a Soil Sample
dry soil sample
set of 4 screen sieves
A dried soil sample can be run through the sieves to prepare it for further tests, such as the pH test.
Measuring Soil pH
Measuring Soil pH
dry soil sample
The pH of the soil sample tells how acidic or basic it is. 7 is neutral. Numbers higher than 7 are basic; numbers lower than 7 are acidic. It is important to know the pH of the soil because it affects the activity of the chemical elements in the soil and it influences what can grow in the soil. Different plants grow best at different pH values. The parent rock, the pH of the soil water, activities of organisms living in the soil, and uses of the land around the soil all affect the pH of the soil.
Measuring Water Temperature
soil temperature probe
12 cm finish nail
5 cm thick wood block with hole
Soil temperatures vary with depth, air temperature and soil moisture, and change more slowly than air temperatures. *Soil thermometers are most sensitive on the 2 cm tip so they should be inserted 2 cm beyond the depth being measured.
Measuring Soil Water Content
soil sample taken using “Z” sampling method
moist soil sample mass:_______
dry soil sample mass: _______
water content of the soil sample =_______
All land plants and animals depend on sufficient levels of water in the soil. Soil moisture (along with other properties of the land and climate) determine what kinds of plants can grow. Soil acts as a sponge and holds water for the roots of plants. Some soils are more effective at this than others.
Comparing Soil Porosity
3 rubber stoppers
3 cotton balls
3 graduated cylinders
50 mls. each of 3 different soil samples
The more porous the soil, the more easily water will pass through it.
Materials and Equipment:
List of material can be extracted from the experiment section.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Write any calculation that you may do in your project report.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.