Module 7: Soils and a Systems Approach to Soil Quality

Goals

• Students will be able to describe different types of cropping systems types, soil tillage practices, and indicators of soil quality.
• Students will be able to interpret the affect of cropping systems and soil tillage approaches on soil conservation and quality.
• Students will be able to distinguish which crop and soil management practices promote soil health and enhanced agroecosystem performance.

​Learning Objectives

After completing this module, students will be able to:

• Define and provide an example of some cropping system practices (ex. monoculture, double crop, rotation, cover crop, intercrops).
• Define soil quality and describe some indicators of soil quality.
• Explain some tillage systems and how tillage practices affect soil quality.
• Interpret how the integration of cropping and tillage systems can promote soil conservation and quality.
• Analyze and prescribe some cropping systems and tillage practices that promote soil quality and other agroecosystem benefits.

This module is designed to introduce undergraduate students to cropping systems, tillage systems, the concept of soil quality or soil health, and a systems approach to managing soil quality for agriculture. This module was designed to follow modules of this course that introduce soils, climate and water, and crops. It can, however, be used in other courses, provided that students have been introduced to soil science and types of crop plants.

This two-part module is designed for one week of classroom sessions, or online or blended classes. We piloted the module in a blended course in which students read the material and completed the activities and a formative assessment online. Students then read the second part of the module online, took a quiz online and met with the instructors for one classroom session. In the classroom, we discussed the students' completed formative assessments, quiz questions they had difficulty with, and briefly reviewed important course themes. Then in class, students worked on the summative assessment with a partner or in groups of three, and could share ideas, ask each other questions, and collaborate. Instructors could observe and prompt students with questions or offer assistance.

This module introduces students to soil quality or soil health and agricultural practices that impact soil quality for agriculture. The module builds on soil and crop concepts from earlier modules to explore soil quality and how crop and soil management practices impact soil. It begins by introducing cropping practices such as monoculture, crop rotations, intercropping, and cover crops and then introduces soil quality and indicators of soil quality. In the second part of the module, tillage practices are explored, and a systems approach that integrates cropping and tillage practices to managing for soil health is presented. Students engage with the concepts by:

• Reading the course pages online and watching the online embedded videos
• Completing the embedded activities
• Doing outside reading on websites that are linked into the course pages
• Completing formative assessment activity
• Completing a summative assessment that asks students to analyze and interpret soil and crop data from a 12 year cropping systems experiment.

Students can complete this module in the classroom, online, or in a blended format. If the module is used for a class that meets two or three times a week, students can initiate the formative and summative assessment towards the end of class with or without a classmate, and the completed assessments can be the basis for discussion and clarification in a follow-up classroom meeting.

• Student Materials - Module 7: Agroecosystems: Soils and a Systems Approach to Soil Quality

Keeping the same due dates and coursework expectations for this module as in the rest of the course, can help students get into a routine and complete the reading and activities prior to coming to class. Then students can also benefit more from class time to apply and clarify what they have learned while interacting with their classmates and the instructor during class. If the module is used in a classroom, the formative and summative assessments can provide activities with real world data to engage students in higher order active learning with classmates and assistance from the instructor.

In the piloted blended course, the online quiz and formative assessments were due prior to attending the class that met once a week. In class, we discussed material from the online quiz and formative assessment that were difficult for students. Some themes of the module were briefly reviewed, and depending on how much clarification was needed, about one-third or more of the class time was allotted for students to work on the summative assessment with a partner or in groups of three. The group work provided students an opportunity to discuss their ideas, ask and answer each others' questions, collaborate in the analysis, and ask questions of the instructor.

What students found difficult

Since there are many soil properties and indicators of soil health, identifying which are most significant can be confusing. An embedded reading about soil organic matter and why it is important helps address this, and the revised formative assessment now requires students to discuss why organic matter is important and how it affects multiple soil functions.

Although students had been introduced to soil and crop science in prior modules, this module requires recalling key concepts and applying them to understand how agricultural management practices impact soil quality. Some students initially overlooked the significance of annual versus perennial crops to soil properties in the summative assessment, and instead discussed tillage frequency differences. Prompting students in class to recall annual and perennial crop lifecycles and how their above and below ground biomass differs appeared to help students consider which crops have more potential to reduce soil erosion and return organic matter to the soil. In addition, instructors may want to ask the class to collectively identify the lifecycle of the crops in the summative assessment. The questions in the summative assessment have also been revised to encourage students to consider crop lifecycles to help them interpret differences in cropping system performance.

Reflection

This module reviews a range of cropping and soil tillage practices, and explores how plants and soils interact to impact soil health for agriculture. Prompting students to recall and link these practices to the earlier soil, water, and crop science modules can help students make the connections and enhance their understanding. This is an opportunity to examine how these components interact and function in agroecosystems; an opportunity to encourage systems thinking.

This module has two assessments:

• Formative Assessment: Soil health indicators & practices to promote soil health Soil Quality Formative Assessment
• Formative Assessment Grading Key (for instructors only
  Formative Assessment -- private instructor-only file
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• Summative Assessment: Interpreting a 12 Year Summary of Crop and Soil Management Research from New York Systems Approach to Soil Quality Summative Assessment
• Summative Assessment Grading key (for instructors only:
  Summative Assessment Key (for instructors only) -- private instructor-only file
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Reading materials that are online and embedded in the course pages for students to read:

Magdoff, M. and van Es. H. Chapter 1. 2009. Healthy Soil, Chapter 2 Organic Matter: What it is and why it's so important, Chapter 16 Tillage. In "Building Soils for Better Crops. Edition 3." Sustainable Agriculture Network, USDA. Beltsville, MD. http://www.sare.org/Learning-Center/Books/Building-Soils-for-Better-Crops-3rd-Edition/Text-Version

Soil Quality Indicators: Measures of Soil Functional State: http://soilquality.org/indicators.html and Soil Quality Management:Key Strategies for Agricultural Land: http://soilquality.org/management.html. NRCS East National Technology Support Center, NRCS National Soil Survey Center, ARS National Laboratory for Agriculture and the Environment, NCERA-59 Scientists, and Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign.

References

Erosion Control Measures for Cropland: University of Nebraska Plant and Soil ELibrary http://passel.unl.edu/pages/printinformationmodule.php?idinformationmodule=1088801071

Karlen, D.L., M.J. Mausbach, J.W. Doran, R.G. Cline, R.F. Harris, and G.E. Schuman. 1997. Soil quality: A concept, definition, and framework for evaluation. Soil Sci. Soc. Am. J. 61:4-10.

Magdoff, F. and H. VanEs. 2009. Building Soils for Better Crops. Edition 3. Chapters on Cover Crops, Crop Rotation and more. Sustainable Agriculture Network, USDA. Beltsville, MD.