Colorado Agriscience Curriculum Development
Section: Plant and Soil Science
Unit: Environmental Factors
Lesson Number: 11
Lesson Title: Nitrogen Cycle
Agriculture Education Standards:
9.8
10.1
10.3
10.4
Colorado Science Standard:
3.24
3.25
3.31
Student Learning Objectives/Enablers
As a result of this lesson, the student will be able to . . .
1. Summarize the major steps of the nitrogen cycle
2. Understand legumes’ role in the nitrogen cycle
Time: Instruction time for this lesson: 50 minutes.
Resources: Modern Biology, Holt, Rinehart and Winston
Agriscience Fundamentals and applications, Cooper and Burton
Introduction to Horticulture, Schroeder/Seagle/Felton/Ruter/Kelley/Krewer
Tools, Equipment, and Supplies
3- five gallon buckets of soil
Nitrogen test kit
Aluminum turkey pans
PSS.HO.1- one cut out per group
PSS.HO.2- one cut out per group
Blank piece of lined paper- 1 per student
Optional Equipment-
15- plant seeds
Poster board
Markers
Rulers
Key Terms. The following terms are presented in this lesson and appear in bold italics:
Nitrogen cycle
Nitrogen fixation
Nitrogen-fixing bacteria
Ammonification
Nitrification
Denitrification
Interest Approach
Students will test different soils for nitrogen levels. Bring in three buckets filled with soil each bucket having a different level of nitrogen (you can add fertilizer in different amounts for each bucket.) Students are going to run a nitrogen test on each sample of soil. Optional: You can follow this by having student’s plant seeds in each of their samples. Have students work in three groups. Each group uses one of the buckets of soil. Every group has to measure out the amount of water they give the plants each day. They also can chart the growth of the plants once a week as well as make comments regarding the plants’ general appearances, growth, etc. (i.e. plant is yellow and wilty vs. sturdy and green).
We are going to set up a lab today to see the results of nitrogen in our soil. First you will need to find a partner. You have 5 seconds. Good, now do not begin until I say, “Go.” Each group will run one nitrogen test on each of the samples I have brought in. You will first come to the front of the room and grab a handful of soil. Remember that you do not need much soil to perform this test. Then you will use a soil testing kit (you may have enough kits for every group.) Once you have the kit, you will follow the directions in the manual for the nitrogen test. Is everyone clear? If you have any questions as you go through the test, please raise your hand and I will come by to assist you.
This test shouldn’t take more than about ten minutes. It can vary depending on your soil testing kit and how many kits you have.
Now that you have the soil tested. You can tell that each soil has a significant difference in nitrogen levels. How do we get more nitrogen in some of the soil and less in other soil?
Students should answer that you add fertilizer or organic matter. Nitrogen levels in soil can also decrease if it has been used by plants or leached out due to water.
Optional: Now I need you to divide into three evenly sized groups. Each group is going to have one bucket with the soil you just tested. Each group is going to plant the seeds that I am providing in their bucket. Now remember in any scientific process we have to do everything the same to make sure that our outcome is accurate. So each group has to water at the same time of the day and add the same amount of water. You also have to make sure that all three groups plant the same number of seeds. Thus, we are going to plant 5 seeds in each bucket. Once you plant the seeds and get them watered, you are going to make a chart. This chart will show the amount the plant grows each week. So you will have to measure all of the plants each week (plants will take 14-21 days on the average to germinate, so students may choose not to start their chart for a few weeks.)
You can use any seed of your choice, but it is recommended not to use legumes as legumes actually produce nitrogen. You may also have the students test the nitrogen levels each week to see how much the plant has used. This lab is great to refer back to when you teach other areas such as: Law of diminishing return and fertilizer application.
SUMMARY OF CONTENT AND TEACHING STRATEGIES
Objective 1. Summarize the major steps of the nitrogen cycle
Students will find the key terms and definitions on a modified Go Get It E-moment. You will need two aluminum turkey roasting pans for each group. Each pan will be filled with the soil. Preferably there will be two teams of twelve, but you may choose a different number of teams or size of teams, as long as you have no more than twelve to a team and the teams have even numbers. Each team will have two groups, one group for terms and one group for definitions. You will cut out the terms and definitions found on PSS.HO.1 & 2. You will need to print off the same number of copies of PSS.HO.1 & 2 as you plan on teams. Put the terms in one pan with soil and the definitions in the second pan. Repeat this according to how many groups you have. Mix pieces of paper into the soil.
You are now going to compete to find the key terms that relate to the nitrogen cycle. I will divide you into teams by randomly numbering you off. Remember which number I give you. Now team number 1 can come stand right here. Team number two - right here. Team number three, etc. Now within your teams, I need you to form two single file lines facing the aluminum trays I have on the front table. The left line of your group will be looking for a term, while the right line of you will be looking for a definition that matches the term. The first terms person and the first definitions person will go to the pans and start digging for the paper. Once the team has got a term that matches the definition that the other team member found, they return and the next two from that group will go. The rules are: Rule number 1- you cannot get any soil outside of the pan. If you do, you have to put it all back into the pan before you can head back to the line, Rule number 2- you have to head back across the line before your team member can go, Rule number 3- your team members can help by telling you what definition goes with what term, which means that the team members waiting to go may want some resources to be able to help. Most importantly, once a team has all of the terms with their proper definitions, everyone on the team has to have them written down on their own pieces of paper to win. Is everyone clear on the rules and how the game is played? On your marks, get set, GO!
Once the first team is done, you will need to review their answers to make sure they are correct. Urge the rest of the teams not to stop in case the first team doesn’t have all of them correct. This way, every student must have it written on his/her piece of paper. Once teams have all finished, you may use PSS.PP.1 to show them the nitrogen cycle.
Objective 2. Understand legumes role in the nitrogen cycle
Students will learn that legumes actually put nitrogen back into the soil. This can play a large role in the choices farmers make with their crop rotations. Students will learn this by using the “Little Professor e-moment.” You will need to divide the class into two groups: one group of “Einstein’s,” one group of “Picassos.” You will teach the Einstein’s the lesson while the Picassos sit quietly. Einstein’s will need a blank piece of paper.
Everyone has five seconds to find a partner. 5...4…3…2…1…Time. You now need to decide which one of you is going to be an “Einstein” and which one will be a “Picasso.” You have 5 seconds. 5…4…3…2…1… Time. Now the Picassos will sit silently while I teach the Einstein’s. Picassos, you may read or doodle or whatever you want. Your only rules are as follows: you must stay in your seat, you cannot make any noise, and most importantly, you cannot listen to what I am teaching the Einstein’s. Picassos, are you ready? Okay, Einstein’s, pay attention. We are going to talk a little more about the nitrogen cycle. Now we discussed how organic material, such as dead animals and plants produce nitrogen in the ground. We also discussed how plants then use up that nitrogen. Now we are going to discover something that somewhat contradicts that process, legumes. Do any of you know what a legume is? Okay, it is a plant that actually produces nitrogen. Legumes are very important because they not only produce nitrogen but they are some of the most common agriculture crops. Legumes include crops like alfalfa, peas, peanuts, lima beans and soybeans. In fact these crops are seen all over the United States. However, we know corn is grown in all fifty states and is not a legume, so this raises an interesting question. Do we plant corn in the same field every year? Chances are we do not. However, there are many reason for this. One of the most common is nitrogen levels. Since corn uses up nitrogen, we can actually rotate it with a legume in order to minimize our costs of fertilizer and help replace the nitrogen levels in the soil. This does not mean that we do not have to add fertilizer to legumes or corn crops that are in a rotation. We may still have to add other important nutrients to our soil for any of these crops to have maximum production. Einstein’s, do you have the material? Okay, Picassos, come back to us. The Einstein’s have been educated on an important topic, and now it is their job to teach it to you. Picassos, look at your Einstein, and say, “Oh wise one, please share your knowledge with me.”
Allow five minutes for the Einstein’s to teach the lesson to the Picassos.
Review/Summary
Have students do a Party Host Moment. Ask nine students to volunteer. You will pick one to be the party host. Ask him/her to leave the room for a couple of minutes. Then have the remaining volunteers pick what they want to be. It is recommended to use the following: Corn, Legume, Nitrogen cycle, Nitrogen fixation, Nitrogen-fixing bacteria, Ammonification, Nitrification, and Denitrification. Challenge them to use what they know about each one to demonstrate who they are supposed to be. Remind them that they cannot tell the party host who they represent. Once the party host figures out who they are, they may take a seat. You may need to give your volunteers a minute to review what functions their personality performs.
Application
Extended Classroom Activity:
Have students set up a composting station in the greenhouse, outside, or in the shop. Students can test nitrogen levels and try to make a productive compost.
FFA Activity
Have students compete in the local speaking contest and utilize the topic of crop rotations. Encourage them to explain how legumes can help producers.
SAE Activity
Have students set up a composting station in the greenhouse, outside, or in the shop. Students can test nitrogen levels and try to make a productive compost. Students may create their own compost either for their own garden or to sell to gardeners in the area as their SAE.
Evaluation
(PSS.Nitro.ASSESS)
Answers to Assessment:
1. The pathway that nitrogen follows within an ecosystem
2. Nitrogen fixation- The process by which gaseous nitrogen in the air is converted into ammonia
Nitrogen-fixing bacteria- Lives in the roots of legumes and convert atmospheric nitrogen into ammonia
Ammonification- in the nitrogen cycle the formation of ammonia compounds
Nitrification- The process in the nitrogen cycle by which nitrites and nitrates are produced
Denitrification- A final step in the nitrogen cycle, during which nitrogen gas is returned to the atmosphere.
3. Crop rotations with legumes can help minimize the cost of fertilizer and fertilizer application.
Suggested Scoring:
1. 5 points
2. 3 points per answer
3. 5 points
Total- 25 points
(PSS.Nitro.ASSESS)
Name: ______
The Nitrogen Cycle
1. Describe the Nitrogen cycle in your own words.
2. Draw a line to match the following terms to their definitions.
Nitrogen fixation in the nitrogen cycle the formation of ammonia compounds
Nitrogen-fixing bacteria A final step in the nitrogen cycle, during which nitrogen gas is returned to the atmosphere.
Ammonification Lives in the roots of legumes and convert atmospheric nitrogen into ammonia
Nitrification The process by which gaseous nitrogen in the air is converted into ammonia
Denitrification The process in the nitrogen cycle by which nitrites and nitrates are produced
3. Describe in your own words how crop rotations can help a producer.