Nutrient Management in Agroecosystems

TPSS 450




You will become familiar with basic concepts of nutrient availability and cycling in agroecosystems and demonstrate proficiency in making nutrient management decisions. We will discuss how nutrient loss from agricultural ecosystems
affects unmanaged ecosystems and in which ways sustainable agricultural practices affect the fate of nutrients.
Specific learning outcomes include:
    • Describe major nutrient cycles in agro-ecosystems
    • Identify key biological, chemical, and physical processes regulating nutrient input, output, transformation, and plant              availability
    • Calculate quantities of nutrient input, available nutrients, and crop nutrient removal
    • Choose appropriate soil fertility evaluation techniques and nutrient management plans
    • Discuss the environmental impacts of agricultural nutrient management


Biological, chemical, and physical processes governing the cycling of nutrients in agroecosystems, crop and livestock production, and the effects on surrounding unmanaged ecosystems.


CHEM 161 and TPSS 304, or consent



Soil Fertility and Fertilizers,2013, J. Havlin, J. D. Beaton, S. L. Tisdale, and W. L. Nelson (8th edition) Prentice Hall, New Jersey.

    Building Soils for Better Crops. Second Edition. SARE Handbook Series Book 4. Magdoff, Fred and Harold VanEs. Chapters available online (free) at http:/ fwww.sare.orgfpublicationsfbsbcfbsbc.pdf.
    The Nature and Properties of Soils. Nyle C. Brady and Raymond Weil. Prentice Hall, latest edition is 14-E (2008). Nutrients: Chapters 12-16 and 20.

Films and videos:

Video and PowerPoint presentations are used to supplement lectures

Field Trips:


Course organization:

Course Schedule:
Unit I. Introduction to Agroecology and Nutrient Cycles
        Week 1    The Agroecosystem concept
                        Food production -past, present, future
                        History of soil fertility
        Week 2    Global nutrient cycles
                        Carbon, nitrogen, phosphorus, sulfur
Unit II. Nutrient management for agricultural production
        Week 3    Fertilizer basics and calculations
        Week 4    Soil/ plant relationships
        Week 5    Chemical, physical, and biological processes that determine nutrient availability
        Week 6    Nutrient management of animal agricultural systems
        Week 7    Nutrient management planning tools
Unit III. Nutrient losses and impacts to the environment
        Week 8    Nutrient use efficiency
                        Phosphorus mining
        Week 9    Reactive nitrogen pollution & Eutrophication, Air pollution
                        Greenhouse gas emissions & Climate change
Unit III. Sustainable agricultural nutrient management practices
        Week 10    Recycling of agricultural wastes
        Week 11    Precision agriculture and fertigation
                          Agroecosystem diversity and stability
        Week 12    Management of soil organic matter
Unit IV. Systems Approach to Agriculture (case studies in Hawaii)
        Week 13     Case study 1: Integrating crop and livestock production
        Week 14     Case study 2: Integrated resource management



Grade Distribution
Activity %
Homework 20
1st Exam 15
2nd Exam 15
Final Exam 25
Laboratory participation 10
Laboratory project 15
    Homework assignments will be due at the beginning of class one week from the day they were assigned. For assignments requiring quantitative calculations, all work must be shown to get full credit. No late assignments will be accepted.
    Three exams will be given to assess your understanding of course content. The first two exams will include material in one to two units. The final exam will encompass all course material.
    In the laboratory section of this course, you will receive hands-on experience with analytical techniques. Attendance and active participation in laboratory activities is critical. A key part of your grade will be a semester-long research project to be conducted during laboratory sessions. The project can be done individually or with a partner. After choosing a topic, you will develop a greenhouse experiment that will give you further insight into agricultural nutrient cycling. Results from the project will be presented in the forms of a research paper and short oral presentation.