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Kansas has a diverse climate from the east to west ends of the state. In many parts of the state, corn farms are rain-fed, known as dryland or non-irrigated farms. These farmers normally receive enough rainfall to raise a crop. As you move toward the western part of the state, the climate is more arid and more farmers supplement their crops with irrigation, with the water sources coming mainly from underground aquifers. Farmers also can irrigate their crops from surface water sources, such as rivers and ponds. Many areas of the high plains region of western Kansas benefit from the Ogallala Aquifer, which supplies a water source for irrigation. Yet, the aquifer is a limited resource, and farmers are working hard to extend its life by finding ways to use less water to produce their crops.
When considering the irrigation needs of commercial crops, farmers must consider several variables. Is there groundwater or surface water available to irrigate the crops? Are the costs associated with irrigating justified economically? What is the best way to ensure that the water reaches the plant roots for the most benefit with the least amount of waste? Wind, evaporation, and runoff are all working against the farmer’s goal of getting the water into the soil and, ultimately, into the roots of the plant itself. With multiple types of systems available to help meet the demands of water delivery, it is critical to understand some basics of irrigation. In this lesson, students will construct and evaluate some of the multitude of irrigation possibilities based on the amount of water that reaches deep enough in the soil to be taken up by the plant.
Science
Language Arts
Math
As with any instance using water and electricity, make sure that you are not allowing electrical outlets to be splashed or become wet during the prototyping process.
Length of Time for Preparation: 20-30 minutes Length of Time for Classroom Teaching: 2-multiple class periods, depending on instructional choices.
Irrigation has been one of the most important agricultural advances of all time. The practice of irrigation of crops has been in place for more than 6,000 years with the first evidence being traced back to Mesopotamia. Early irrigation focused on moving water from one location to another generally through the construction of troughs or furrows that then used gravity to move the water from the source toward the crops. This early irrigation worked to provide much needed water to parched and marginal ground so that agricultural products were more reliable for the farmer and the cultures that surrounded farming areas. Later, pumps, such as simple windmill pumps, were utilized to help bring water from underground water reservoirs and low-lying water source to the surface. Simple gravity flow furrow irrigation has drawbacks, such as having to overwater parts of the field just to ensure those downhill would get enough, if any, water. In 1952, Frank Zybach, a farmer from Nebraska, developed center pivot irrigation. In center pivot irrigation, farmers could more reliably spread water over the entire field from a single line of pipe, supported by towers with wheels, moving it around a central pumping location in the middle of the field. These modern versions of pivots are still used today by farmers around the world.
In recent years, driven by the need to conserve precious freshwater resources, farmers and industry professionals are developing and experimenting with new types of irrigation water application devices, such as LESA (low elevation spray application) and MESA (medium elevation spray application). LESA utilizes the center pivot but allows for drop hoses that spray water 2-4 feet above the ground. MESA uses nozzles dropped 5-8 feet above the ground. LEPA (low energy precision application) utilizes bubbler nozzles that gently deliver water just 8-18 inches above the ground to combat wind-drift and reduce evaporation loss. Some LEPA systems use drag hose socks to apply water directly to the ground and into small basins or pits to prevent the water from moving from the application point and allow water to be absorbed. Another option of applying water to the ground surface is MDI (mobile drip irrigation), which applies water directly on the soil by utilizing center pivots that have microirrigation driplines that come in direct contact with the soil instead of being positioned above the crop. SDI (subsurface drip irrigation) is an irrigation system options that deploys underground microirrigation drip-lines running parallel and in close proximity to the crop rows themselves. Water is then pumped directly into the pipe system and allowed to diffuse into the soil, applying the water directly into the crop root zone. Since the water is applied below ground, evaporation losses and water runoff potentials are eliminated.
Regardless of the system, one basic fact is necessary to understand in irrigation. Mother nature can’t always be depended on to deliver water at the right place, time and amount. In drier areas of the state, for good stable yields and increased production, well-designed efficient systems must be developed to maximize the output of acreage while decreasing inputs. This will also allow farmers to be good stewards of the natural resources that are available to them, making sure that the water resources we have now are not depleted but carefully utilized so that future farmers will have the same opportunities.
Classroom Discussion
Activity 1: The Water Cycle Review
Activating Prior Knowledge:
Materials needed: large poster paper or white boards, 3 colors of writing instruments.
Procedure for Lab
Activity 2: How Much Water is Needed? Quick Discussion and Calculation.
This is a teacher-led discussion that can be completed at the chalkboard or Elmo. Students should be writing down the calculations, as they will be important data points for their design project later on.
Teacher: Let’s calculate how much water is needed for an average yield of corn. Most corn needs 20-25 inches of water during the vegetative stage which is the emergence to maturity stages of the growing season. This will help to produce over 250 bushels of corn per acre of land. How much water is that? Let’s try and convert this into a measurement we can understand, such as in terms of gallons of water.
Students: Have students complete the calculation below. Here is the conversion you will need: 1 in. of rain per acre is about 27,154 gallons How many gallons of water would be needed total?
27,154 gallons x 22 in. = 597,388 gallons of water
Teacher: That’s a lot of water, right? What would that look like? The average high school competition pool in Kansas holds about 162,000 gallons of water. So, the amount of water we would need would fill up 3.68 or about 3 ¾ pools. Remember, this is per acre of land. What can we get from that much water?
Suppose that at harvest time, your data shows that you have an average of 200 bushels per acre of your corn. How many gallons of water were used to produce one bushel?
Students: Students can now calculate gallons per bushel. It may be helpful to write it on the board gallons per bushel.
597,388 gallons / 200 bushels = 2,986.94. So, let’s say 2,987 gallons for one bushel of corn.
Source: https://articles.extension.org/pages/14080/corn-water-requirements
Provide a student sheet to each student.
Students will research irrigation practices past and present. This could be completed individually or as a group and can be as formal or informal as fits into your time and curriculum needs. Options could range from production of a flier, individual presentation, or a simple research and share, where each member of a group of students researches the pros and cons of each type of irrigation address on the Internet, then shares the information gathered with the group. Overall, the goal is to allow students to better understand the past and present irrigation practices and determine what benefits and drawbacks are seen in each process. Ultimately, students will be using this research to help them evaluate design options in the concluding design activity.
Past and Present: https://water.usgs.gov/edu/wuir.html Irrigation Water Use (Water School)
Short video: https://www.youtube.com/watch?v=24LJSJqpYuY (History Channel on Irrigation) * Please note that this video is from 2009 and technology has improved since then.
Also found on student worksheet.
Problem: You need to get water to your crops, but you want to do it efficiently. Design an irrigation system that will allow you to make up the deficiency of water that you discovered must be covered for you to get a good crop.
Constraints: Use data collected previously to outline the limitations you have in your geographic area (wind, temperature, topography, cost, distance to pump, etc.).
An engineering and designing rubric is located on student sheet.
Utilizing the rubric provided, students can be assessed on the overall design and successful demonstration of their final irrigation design. Again, remember that this lesson can be as large or small as is necessary for individual curriculum needs and should be adapted on a class-by-class basis.
As with any field, research in the next big innovation can drive a huge portion of the business. In the case of irrigation, jobs in the areas of engineering, manufacturing, data collection and analysis, systems operation, and, of course, research and development are all critical to the development of the most efficient systems. As water resources are dwindling and government regulations are being more and more strenuous, it is becoming more important to ensure effective and efficient systems are being developed and deployed.
To learn more about agriculture careers, visit https://agexplorer.ffa.org/.
Any educator electing to perform demonstrations is expected to follow NSTA Minimum Safety Practices and Regulations for Demonstrations, Experiments, and Workshops, which are available at https://static.nsta.org/pdfs/MinimumSafetyPracticesAndRegulations.pdf, as well as all school policies and rules and all state and federal laws, regulations, codes and professional standards. Educators are responsible for abiding appropriate legal standards and better professional practices under a duty of care to make laboratories and demonstrations in and out of the classroom as safe as possible. If in doubt, do not perform the demonstrations.
This lesson is the work product of the Kansas Corn Commission. Our lessons are written in collaboration with Kansas teachers for use in the classroom. Teachers may copy and share this curriculum. Use of this product for commercial or promotional use is prohibited without express permission of Kansas Corn.
As the need to produce more food with less resources grows, it is important that future generations have a better understanding of agriculture and how corn farming and agriculture fit into our daily lives. That’s why the Kansas Corn STEM program provides lessons to teach science through the lens of corn. We are committed to providing free materials and training to support educators.
