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Soil Fertility

Questions? Contact John Sawyer

Professor
Extension Soil Fertility Specialist
Phone: (515) 294-7078
Email: jsawyer@iastate.edu

Antonio Mallarino

Professor, Soil Fertility
Phone: (515) 294-6200
Fax: (515) 294-2458
Email: apmallar@iastate.edu

Soil Fertility Home Page

Welcome to the Iowa State University Agronomy Extension Soil Fertility Home Page. Nutrient topics are listed on the left side. Simply click on a topic of interest and you can find information about that topic, including Extension publications, newsletter articles, conference proceedings and reports, presentations, and links to other related sites. Links also provide access to soil fertility decision aid tools, a photo gallery, and the ISU Soil and Plant Analysis Laboratory.

Current Topic

VALUE OF SOYBEAN TISSUE TESTING FOR PHOSPHORUS AND POTASSIUM

Antonio P. Mallarino, Professor, Department of Agronomy, Iowa State University
June 20, 2016

Soil testing is a useful and commonly used diagnostic tool for making phosphorus (P) and potassium (K) fertilization decisions. Tissue testing has been suggested for decades as another tool for these and other nutrients. However, tissue testing has not been widely implemented for P or K in Iowa or the North Central region because of inconclusive results from limited field calibration research based on crop yield response. Iowa State University (ISU) has no P or K tissue test interpretations for any crop. Therefore, research was conducted to evaluate the value of tissue testing for P and K in soybean. Read on.


Past Current Topics

 

DO YOU KNOW THE STORY OF SOIL?

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Do you know The Story of Soil? Human Health Food Quality Water

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Iron chlorosis symptom - soybean. Photo © John E. Sawyer

Iron chlorosis symptom - soybean. Photo © John E. Sawyer

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