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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.

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Current Topic

POTENTIAL N LOSS - SPRING 2017

John Sawyer, Professor, Department of Agronomy, Iowa State University
May 31, 2017

Lately it seems to be an every-year question, and no exception this spring - has there been nitrogen (N) loss from my applied N? That question should also include what has been the N loss from the soil N supply or residual nitrate-N. There is usually tile drainage every spring (well, probably at some point every spring), and sometimes but not usual in the late fall (remember a couple of years ago). Also, losses if soils become saturated (free water filling the soil pores, standing water, anaerobic conditions) and soils are warm - then denitrification (biological conversion of nitrate to N gas). So some N loss from soils is typically occurring, just can be small or large depending on many factors. Prediction of the effect on N supply, additional N fertilization need, etc. in wet periods is difficult. There are several approaches to take in making estimates of N status or loss. Read on.


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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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