Cenusa Bioenergy High School Curriculumjuly, 2015

CenUSA Bioenergy High School CurriculumJuly, 2015

CenUSA Bioenergy High School Curriculum

July, 2015

Lesson 4: Nitrogen Cycle

This lesson covers the nitrogen cycle. Student will need this knowledge to complete labs and research in following lessons. Lessons are designed for 10th-12th grade students. This lesson was designed for a block schedule; however, it may be shortened and edited to suit the teacher, the material, and the class. This material may also be used in other agricultural classes.

Learning Objectives

At the end of this lesson, students will be able to successfully achieve the following objectives:

Describe the connection of the nitrogen cycle to the production of crops.
Construct an idea of what could be done to reduce the loss of nitrogen from soil.
Differentiate the nitrogen cycle from the carbon cycle.

Academic Standards

Domain:Soil Fertility

Core Standard 13: Students connect soil nutrients and soil management to promote healthy plant growth.

Indiana State Standard:PSS-13.1, PSS-13.3, PSS-13.4

National AFNR Standards:CS.02.04; CS.03.03; PS.02

Next Generation Science Standards:HS-LS1-6, HS-LS2-3, HS-LS2-4

Documentation of Competencies Met by This Lesson

Connection to SAE/Career Development: Agriscience Research - Plant Systems, Emerging Agricultural Technology, Diversified Crop – Entrepreneurship, Diversified Crop – Placement, Diversified Horticulture, Forage Production, Grain Production – Entrepreneurship, Grain Production – Placement

Connection to FFA/Leadership Development/Personal Growth: Anything that involves working with new and emerging technology, plants, or continuing education.

Orvis, Kararo, Long ©PurduePage 1August 2014

CenUSA Bioenergy High School CurriculumJuly, 2015

Curriculum Content Included

Websites Utilized

Supplies Needed

Teaching Content and Learning Activities

4.1 Introduction to the Nitrogen Cycle

Learning Activity: [TITLE]

Teaching Content

4.2 Lab: Water Erosion and Leaching of Nitrogen

Description

Background Information

Learning Objective

Time Requirement

Supplies

Directions

Discussion Questions

Lesson 4: Student Review Questions

Lesson 4: Student Review Questions - KEY

Lesson 4: Teacher Assessment

Supplemental Documents:

Lesson 4 PowerPoint Presentation

Lesson 4 Print Outs

Websites Utilized

Supplies Needed

•2 large disposable aluminum tray (approx. 9”x13”x3”)

•Natural soil from a garden (NOT potting soil from a bag)

•A magnifying glass

•A pair of pointy scissors or the needle of a drawing compass

•2 or 3 books or wooden boards about 1/2-inch thick each

•A watering can

Teaching Content and Learning Activities

Notes.

A PowerPoint presentation is included with this curriculum and includes the follow teaching content and learning activities. You may modify the presentation as needed for your class.

The teaching content and learning activities are presented here in the suggested order of occurrence.

4.1Introduction to the Nitrogen Cycle

Teaching Content

We learned in a previous lesson that carbon cycles through the soil, air, and sea, but did you know that there are more elements that cycle in a similar way? Nitrogen is another element that is essential to life, and, much like carbon, has a natural cycle.

The majority of nitrogen found on earth is actually all around you. Nitrogen gas is two nitrogen atoms bonded together (N2) and makes up the bulk of the atmosphere (around 75-80%). Although nitrogen gas is abundant, it is not very useful in that form, so what happens to nitrogen in order to change this common gas into a valuable resource for plants and animals?

The answer is that nitrogen gas is turned into useful forms of nitrogen, such as nitrites and nitrates, in a variety of ways, called “fixation.” Fixation can happen when a lightning bolt strikes, through industrial chemical processes, or by bacteria in soil or on plant roots, such as many bean varieties, that deposit fixated nitrogen into the soil.

Processes in the Nitrogen Cycle

We will explore the specific steps in the nitrogen cycle a little later, but for now, we just need to know that the nitrogen cycle plays a critical role in the lives of both plants and animals. Plants get the nitrogen they need from either natural sources, such as the soil and water, or manufactured sources, such as applied fertilizer. Nitrogen is a key element in plant body growth, so let’s take a minute to talk about fertilizer sold in stores. Have you ever seen a fertilizer label? Fertilizers are classified with a three-number system. The first number represents the amount of nitrogen, the second number represents the amount of phosphorous, and the third number represents the amount of potassium. This classification system is known as the fertilizer’s N-P-K number ratio, using the periodic table letters for nitrogen, phosphorous, and potassium. Fertilizers that have different N-P-K numbers are useful for different parts of a plant’s life, and choosing one can get quite complex, but know that a high nitrogen number means the fertilizer will help the plant’s body grow quickly.

Natural sources of nitrogen for plant life include soil and water. How does nitrogen naturally get into the soil and water? The answer lies in the circle of life. Outside of nitrogen-fixing bacteria, which we will learn more about later, nitrogen is taken up by animals when they eat plants, or eat animals that eat plants, and returned to the soil and water by animals either while living through their bodily waste, or after death through their bodies decomposing.

The specific steps in the nitrogen cycle are fixation, nitrification, assimilation, ammonification, and denitrification. Fixation occurs when nitrogen gas (N2) is converted into either nitrogen oxides by lightning, or ammonia by bacteria. Reactions shown below are simplified and unbalanced.

Lightning fixation: N2 + O2 NO or NO2(nitrogen oxides) or HNO3 (nitric acid)

Bacteria fixation: N2 + H2 NH3 (ammonia)

Nitrification is the process by which ammonia created by fixation is converted by another type of bacteria into nitrite (NO2-) and nitrate (NO3-) ions. Nitrite and nitrate ions are useful forms of nitrogen for plant life.

Nitrification: NH3 + O2 NOx + H2

Assimilation occurs when an organism eats plants or animals that eat plants and absorb the nitrogen in whatever they ate into their own bodies. Since plants absorb nitrogen and are at the bottom of the food chain, all other organisms higher up on the food chain ultimately get the nitrogen they need to survive thanks to plants.

Ammonification happens when dead organisms, both plants and animals, are decomposed. Nitrogen is turned from whatever form it was in when the organism was living back into ammonia by bacteria and fungi, which can then go through nitrification and be used by plants again.

Nitrogen is turned from useful nitrates back into a gas (N2) and returned to the atmosphere through a complex process called denitrification. This happens due to anaerobic organisms that live in oxygen-free environments taking in nitrates and ammonium and converting them into nitrogen gas and water.

Denitrification:NH4+ + NO2- H2O + N2

Much like the carbon cycle, the nitrogen cycle is a balanced system, and can become unbalanced by a variety of factors. One of the ways excess nitrogen can be introduced into the cycle is through overuse of fertilizers on agricultural crops. Fertilizers can be washed away into water supplies and cause an unnatural increase in nutrients, causing a chain reaction ultimately resulting in damaged aquatic ecosystems. Another way an excess of nitrogen can be introduced into the cycle is through livestock waste running off into streams and rivers. For an example of the damage nutrient runoff can cause, investigate the hypoxic zone in the Gulf of Mexico.

Nitrogen Cycle

Image from tamu.edu

4.2 Lab: Water Erosion and Leaching of Nitrogen

Image from fs.usda.gov

Lab modified from:

Tomecek, S. (2002). Science Lab on Erosion. Retrieved August 26, 2015, from

Description

This lab will help students better understand the process of water erosion and how it contributes to the leaching of nitrogen from soil. Nitrate leaching is one way that the nitrogen cycle can be disrupted.

Background Information

Soil erosion is the detachment of earth material from a surface which is transported via either wind or water to a new location where it is deposited. Water erosion is the focus of this lab, and can be caused by rivers carving a new path, rainfall, or runoff. Runoff on agricultural fields that have been fertilized with nitrates made from nitrogen can cause the nitrates to enter the water supply (called leaching) through soil erosion, thus causing environmental degradation. Runoff is of most concern on bare and/or sloped soil that does not have any cover crop or other vegetation growing on it. This lab will show the differences between vegetative cover and bare soil with regards to soil erosion, and thus nitrogen leaching.

Learning Objective

Upon completion of this lab, students will be able to:

Explain how water erosion can impact the nitrogen cycle
Identify two ways humans can reduce soil erosion

Time Requirement

Approximately 20 minutes.

Supplies

•2 large disposable aluminum tray (approx. 9”x13”x3”)

•Natural soil from a yard with grass still attached (NOT potting soil from a bag)

•Natural soil from underneath grass

•Potting soil

•A magnifying glass

•A pair of pointy scissors or the needle of a drawing compass

•2 or 3 books or wooden boards about 1/2-inch thick each

•A watering can

Directions

Place the natural soil with grass into one of the trays so that it makes a layer on the bottom 2 to 3 inches deep.
Use the scissors or compass needle to punch 6 small holes in one end of the traycontaining soil.
Place the second pan under the end of the dirt-filled pan where the holes are. (The second pan will catch the water as it leaves the top pan.)
Slip 2 or 3 books under the other end of the dirt-filled pan so that it is propped up about 2 inches higher than the end with the holes punched in it.
Using the watering can, pour water for ten seconds into the raised end of the soil and grass-filled pan.
Now examine the soil in the first tray and the water in the second tray. Answer these questions and discuss with your neighbor:
How does the soil look different now?
Is the water clear or contaminated? What is in the water?
Did the soil react the way you thought it would when water was poured in it?
Repeat steps 1-6 with the natural bare soil and the potting soil.
Examine the different soils closely with the magnifying glass. Touch them and run them through your fingers. Answer these questions and discuss with your neighbor:
What are the different soils made of?
Do they all feel the same?
How do you think the different soil parts would react if water was poured on them?

Discussion Questions

As a class, discuss the following questions:

How does water shape the Earth?
What happens to the surface of the soil when the water first hits it?
What happens to the water that comes out of the soil-filled tray and collects in the lowertray?
Do you think it matters if the soil starts out wet or dry?
What would happen if you added a few more books under the pan to make a steeper slope?
Do all soil particles get pushed equally by the water?
What are two ways humans can reduce nitrate pollution from fertilizers?

Lesson 4: Student Review Questions

Name: ______Date: ______

Select T/F for the questions listed below:

1. ______Use of nitrogen-rich fertilizers can add too much nitrogen to nearby waterways as the fertilizer washes into streams and ponds.

2. ______The waste associated with livestock farming adds small amounts of nitrogen into soil and water.

3. ______Increased nitrate levels cause plants to grow rapidly until they use up the supply and die.

4. ______Nitrogen is an important part of non-living things like the air above and the dirt below.

5. ______Atoms of nitrogen stay in one place. They do not move between living things, dead things, the air, soil and water.

Lesson 4: Student Review Questions - KEY

Name: ___ MASTER KEY______Date: ______

Select T/F for the questions listed below:

1. ____T______Use of nitrogen-rich fertilizers can add too much nitrogen to nearby waterways as the fertilizer washes into streams and ponds.

2. ____F______The waste associated with livestock farming adds small amounts of nitrogen into soil and water.

3. ____T______Increased nitrate levels cause plants to grow rapidly until they use up the supply and die.

4. ____T______Nitrogen is an important part of non-living things like the air above and the dirt below.

5. ____F_____ Atoms of nitrogen stay in one place. They do not move between living things, dead things, the air, soil and water.

Lesson 4: Teacher Assessment

As the teacher, reflect on the Lesson 4 and answer the following questions.

What did the students like about this lesson?

What did the students dislike about this lesson?

Did the students find anything difficult in this lesson? If so, what?

What are the strengths of this lesson?

What are the weaknesses of this lesson?

What went well during this lesson?

What did you find difficult or challenging during this lesson?

Where the objectives met effectively during this lesson?

Were the labs or activities relevant to the lesson topic?

Overall, do you have any other suggestions or thoughts about this lesson?