Colorado Agriscience Curriculum

Section: Plant & Soil Science

Unit: Soils

Lesson Number: PS U6 L6

Lesson Title: Organic Matter in the Soil

Colorado Agricultural Education Standards: Ag. II 10.9: The student will demonstrate an understanding of soil fertility and its effect on crop production.

Colorado Science Standards: 4.1: Students know and understand the composition of Earth, its history, and the natural processes that shape it.

Student Learning Objectives (Enablers) As a result of this lesson, the student will …

1. Identify sources of organic matter in the soil. 2. List ways organic matter benefits the soil. 3. Understand soil organic matter’s effect on fertility and land use.

Time: Instruction time for this lesson: 50 minutes.

Resources Soils in our Environment, 7th Edition, Miller & Donahue

Tools, Equipment, and Supplies  Overhead projector or computer with projector  PowerPoint: PS U6 L6 Instructor PowerPoint  1 copy per student of PSU6L1 Job Sheet  1 copy per student of PSU6L6 Student Evaluation  Student Notebooks  Writing tools  Correct number of concentration game packets (student groups of 4)

Key Terms: The following terms are presented in this lesson and appear in bold italics:  Organic  Protozoa  Fallow  Green manure  Humus  Legumes  Bacteria  Organic matter  Rhizobia  Fungi  Tilth

Interest Approach Use the concentration game cards at the end of this lesson plan to introduce the key terms. This will get students out of their seats and create some initial understanding of words used in the lesson.

Today we are going to talk about an essential part of the soil. To begin today’s lesson, I need you to get into groups of four. You may chose your own group as long as you move quickly when I say go. Are there any questions? Ready – Go. Allow students to move quickly into the groups. Be sure to have made enough complete concentration packets for your number of students. It is handy to make each set a different color of paper to allow them to be used year after year. Be sure to mix up the order of the papers as they are made into packets. Now that you are in your groups, I am going to give you a stack of papers. I need you to keep the papers face down. Spread them out on the table or floor in the middle of your group. Do not peak at the other side of the paper. When I say “concentrate” – this is what you are to do. You are to match the definitions with the terms. You can have no more than two papers turned up at a time. Each group needs to designate a counter. The counter needs to have a piece of paper and writing utensil. Each time you return a paper to face down because they do not match – make a tally mark on your paper. The group that gets all of their definitions and terms matched with the least number of tallies will be the winner. Please be sure to use integrity when tallying for your group. When you have a match – you may remove those two papers from the group. Are there any questions? Ready – set – concentrate. Roam around the groups to ensure compliance with the objectives and rules. We are now going to see how many each group got correct. Go through the terms – answers listed below. Good job – I hope you will now understand some of the terms used in today’s lesson. I need you to pick up the papers, return them to me and take a seat. Thank you.

Answers to matches: Organic: Containing C (carbon) and/or other elements such as N (nitrogen) and S (Sulfur) and synthesized by living organisms.

Green Manure: Crops such as legumes or grasses that are grown to be plowed or spaded into soil to increase humus content and improve soil structure (cover crop).

Bacteria: Single celled microorganisms; some cause human, animal or plant diseases; others are beneficial

Fungi: Plantlike organisms that have no chlorophyll; they get their nourishment from living or decaying organic matter.

Protozoa: A group of one celled organisms that generally do not contain chlorophyll; including amoebae, paramecia, flagellates and certain spore-forming organisms; sometimes classified as one-celled animals.

Humus: Brown to black substances or relatively high molecular weight formed during random synthesis reactions in soil. The stable fraction of the organic matter in soil that persists once readily decomposable material is gone.

Organic Matter: Matter found in, or produced by, living animals and plants, which contain carbon, hydrogen, oxygen and often nitrogen and sulfur. Tilth: The physical condition of a soil in relation to the ease of its tillage and fitness as a seedbed for crop growth.

Fallow: Leaving uncropped or untilled.

Legumes: A family of plants, including valuable food and forage species, such as peas, beans, soybeans, peanuts, clovers, alfalfas, sweetclovers, lespedezas, vetches, and kudzu. With aid of symbiotic bacteria, they can convert nitrogen from the air to build up nitrogen in the soil. Many of the nonwoody species are used as a cover crop and are plowed under for improvement of the soil.

Rhizobia: Collective name for bacteria of the genus Rhizobium, which are capable of symbiotic nitrogen fixation with legume plant roots

Summary of Content and Teaching Strategies

Now that you have had in introduction to this important soil component – who can tell me why it is so important. Display PS U6 L6 Slide #2. Encourage a variety of class discussion.

I would like you to take notes today as we move through this lesson. Students can either take general notes into their notebooks or the job sheet provided with the resources at the end of this lesson plan can be utilized.

Objective 1: Identify sources of organic matter in the soil.

Slide # 3 What is Organic Matter?  all plant and animal residues in the soil

Slide #4 What things make up soil organic matter?  Plant & animal residues  Barnyard manure  Green manure  Dead roots  Insect & worm carcasses & excrement  Dead soil micro-organisms (bacteria, fungi, protozoa)

Slide #5 What is Green Manure?  a crop grown for its organic matter  green manure crops are generally plowed under while they are still green  Examples = sweet clover, rye Discuss other examples relevant to your area.

Slide #6 What two things have greatly lowered the Organic Matter content of soil?  soil erosion  continuous cropping

Objective 3: Understand soil organic matter’s effect on fertility and land use.

Slide #7 How can organic matter be increased?  crop residues  barnyard manure  green manure

Slide #8 What is the difference between organic matter & humus? Organic matter is dead plant & animal life before it has been broken down Humus = relative stable product of the decomposition of organic matter

Slide #9 What is Mineralization?  organic matter is broken down into simple mineral compounds  Due to the action of bacteria & fungi

Slide #10 When organic matter breaks down, what is released for the crop's use?  Nutrients (sulfur, nitrogen, phosphorous, potassium, calcium, magnesium + micronutrients)

Objective 2: List ways organic matter benefits the soil.

Slide #11-12 How does Organic Matter Improve Soil? 1) increase water holding capacity 2) nutrients attach to O.M. 3) O.M. improves tilth (aggregate) 4) The amount of humus in soil is directly proportional to the amount of nitrogen in soil 5) Soils high in O.M. are easily worked and may be described as having good tilth. 6) Improves soil structure 7) Improves aeration

Slide #13 Benefits of Organic Matter  Organic Matter promotes granulation of soil by binding soil particles into granules.  O.M. makes clay soils less sticky and improve tilth.  Deeper root growth and water entry and storage are improved as well as aeration of the soil.

Slide #14 Organic Matter & Sandy Soils • Sandy soils have good aeration but dry out quickly. Sandy soils increase water holding capacity and have less erosion as O.M. is added? Slide #15 What is the largest source of O.M. in the soil?  plant roots

Slide #16 Which is the most preferred green manure, legumes or non-legumes?  legumes- added nitrogen

Slide #17 What is nitrogen tie-up?  microorganisms in the soil use the nitrogen in the soil to break down organic matter, thus it is temporarily "tied up" (used as food)  this is very important when considering re-cropping and not allowing the soil to have a year in fallow to allow for mineralization in order to reduce the nitrogen tie-up.

Slide #18 Is organic matter a good mulch? Yes  Reduces surface evaporation  Equalizes soil temperature  Increases soil animal life  Reduces soil erosion

Slide #19 Detrimental effects of soil organic matter  Energy source for many disease organisms – ensuring their survival in the soil  Excessive amounts of plant residues are difficult to incorporate into the soil and hinder some planting operations  Addition of organic matter into soil may temporarily increase the carbon:nitrogen ratio – thus limiting the available nitrogen to the current crop

Slide #20 – 23 Now that we have covered most of the material – let’s put our thinking caps on.

How many square feet are in an acre?  43,560 What is an acre-six inches?  six inches of soil over an acre An acre-six inches weighs how many pounds?  2 million Soil Conservation A typical farmer is doing a "good job" of soil conservation if he loses less than 1/16" of topsoil each year. How many pounds of soil does he/she lose each year if he/she loses 1/16"? How many tons? (extra credit)

Slide #24 How long does it take to create soil? It takes 100 to 400 years to create 1" of topsoil. Review/Summary

Use the Cartographer e-moment to summarize the days’ lesson.

Are there any questions about today’s material? I need you all to take out a blank piece of scratch paper and a pencil. I would like for you to listen to the directions and then begin. I want you to draw a summary of what is happening in the soil as it gets organic matter. You can draw this cycle in your own way – just be sure to cover the basics of soil organic matter. Are there any questions? You may begin.

Ensure students understand the basics by roaming around the room and viewing the sketches.

Application Extended classroom activity: Take a walk around the school property looking for signs or evidence of organic matter.

FFA activity: Develop a worm farm in the classroom or to use with PALS.

SAE activity: Have a student investigate the organic matter on their farm or garden.

Evaluation Use the attached evaluation as needed.

Answers to Assessment:

J G I F C A E H B D K PS U6 L6 Student Question Sheet

Enterprise: Soils Name: Job: Organic Matter in the soil Date:

1. What is organic matter? 2. What things make up soil organic matter? 3. What is green manure? 4. What two things have greatly lowered the organic matter content of soil? 5. How can organic matter be increased? 6. What is the difference between organic matter & humus? 7. What is mineralization? 8. When organic matter breaks down, what is released for the crop's use? 9. How does organic matter improve soil? 10. What are the benefits of organic matter? 11. How does organic matter affect sandy soils? 12. What is the largest source of O.M. in the soil? 13. Which is the most preferred green manure, legumes or non-legumes? 14. What is nitrogen tie-up? 15. Is organic matter a good mulch? 16. What are the detrimental effects of soil organic matter? 17. How long does it take to create top soil? PS U6 L6 Student Evaluation

Organic Matter Evaluation

Name: Date:

Match the following terms and definitions.

______Bacteria B. A family of plants, including valuable food and forage species, such as peas, beans, soybeans, peanuts, clovers, alfalfas, ______Fallow sweetclovers, lespedezas, vetches, and kudzu. With aid of symbiotic bacteria, they can convert nitrogen from the air to build ______Fungi up nitrogen in the soil. Many of the nonwoody species are used as a cover crop and are plowed under for improvement of the soil. ______Green Manure C. A group of one celled organisms that generally do not contain ______Humus chlorophyll; including amoebae, paramecia, flagellates and certain spore-forming organisms; sometimes classified as one-celled ______Legumes animals.

______Organic D. Brown to black substances or relatively high molecular weight formed during random synthesis reactions in soil. The stable ______Organic Matter fraction of the organic matter in soil that persists once readily decomposable material is gone. ______Protozoa E. Collective name for bacteria of the genus Rhizobium, which are ______Rhizobia capable of symbiotic nitrogen fixation with legume plant roots

______Tilth F. Containing C (carbon) and/or other elements such as N (nitrogen) and S (Sulfur) and synthesized by living organisms.

A. G. Crops such as legumes or grasses that are grown to be plowed or spaded into soil to increase humus content and improve soil structure (cover crop).

H. Leaving uncropped or untilled.

I. Matter found in, or produced by, living animals and plants, which contain carbon, hydrogen, oxygen and often nitrogen and sulfur.

J. Plantlike organisms that have no chlorophyll; they get their nourishment from living or decaying organic matter.

K. Single celled microorganisms; some cause human, animal or plant diseases; others are beneficial

L. The physical condition of a soil in relation to the ease of its tillage and fitness as a seedbed for crop growth.

Organic Containing C (carbon) and/or other elements such as N (nitrogen) and S (Sulfur) and synthesized by living organisms. Green Manure Crops such as legumes or grasses that are grown to be plowed or spaded into soil to increase humus content and improve soil structure (cover crop). Bacteria Single celled microorganisms; some cause human, animal or plant diseases; others are beneficial Fungi Plantlike organisms that have no chlorophyll; they get their nourishment from living or decaying organic matter. Protozoa A group of one celled organisms that generally do not contain chlorophyll; including amoebae, paramecia, flagellates and certain spore-forming organisms; sometimes classified as one-celled animals. Humus Brown to black substances or relatively high molecular weight formed during random synthesis reactions in soil. The stable fraction of the organic matter in soil that persists once readily decomposable material is gone. Organic Matter Matter found in, or produced by, living animals and plants, which contain carbon, hydrogen, oxygen and often nitrogen and sulfur. Tilth The physical condition of a soil in relation to the ease of its tillage and fitness as a seedbed for crop growth. Fallow Leaving uncropped or untilled. Legumes A family of plants, including valuable food and forage species, such as peas, beans, soybeans, peanuts, clovers, alfalfas, sweetclovers, lespedezas, vetches, and kudzu. With aid of symbiotic bacteria, they can convert nitrogen from the air to build up nitrogen in the soil. Many of the nonwoody species are used as a cover crop and are plowed under for improvement of the soil. Rhizobia Collective name for bacteria of the genus Rhizobium, which are capable of symbiotic nitrogen fixation with legume plant roots.