15 Soil Nutrient Management

Proper soil fertility is essential for achieving optimum yields and plant health. It is also critical for minimizing the costs of inputs like fertilizer or irrigation water, as well as for reducing the environmental impacts of production agriculture or manicured landscapes. The key to proper soil fertility is soil testing. We will first tour the K-State Soil Testing Lab. The staff will walk the class through the process, include sample submittal, costs, pH analysis, and nutrient analyses. This will be followed by a problem set in which students will make fertilizer recommendations using soil test results and publically available K-State extension bulletins and resources.

Learning Objectives

  • Learn to interpret information contained in a soil test report.
  • Make fertilizer recommendations based on soil test results.
  • Become familiar with K-State resources as well as publications available to farmers and gardeners.

Materials

Recommended Reading

  • Soil Analysis (Kansas State University Department of Agronomy, 2020)

Prelab Assignment

Using the recommended reading and the introduction to this lab, consider the questions listed below. These definitions/questions will provide a concise summary of the major concepts to be addressed in the lab. They are also useful as study notes for exams.

  1. Explain why it is important to collect a soil sample from a representative area of soil and why it is common practice to mix many samples into one composite sample.
  2. Explain the statement that “soil testing laboratories do not determine the concentration of plant-available nutrients in soils”. What do they actually determine?
  3. Explain why applying fertilizer to achieve maximum yield may not achieve maximum profit.
  4. In addition to soil testing, what other diagnostic tools are used to assess fertility?

Activity & Assignment: Problem Set

A problem set will be provided to you at the beginning of the lab. It will familiarize you with how fertilizer recommendations are made based on soil tests. Materials required to complete the problem set are available as printed copies in the lab or as PDFs and Excel Spreadsheets online. You will complete the problem set during lab.

License

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Soils Laboratory Manual by Colby J. Moorberg & David A. Crouse is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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