Soil Fertility - Understanding the Basics

Agriculture and Natural Resources Extension
Iowa State University

Title of Success Story

Soil Fertility – Understanding the Basics

Public Value (now or future)
(Impact:  Who benefits beyond participants and how?  What conditions changed?)

Improved crop production through good soil fertility management means more dollars produced per acre, which has a ripple effect in the local economy. Additionally, reduction of soils with excessive nutrients reduces the risk of off-site nutrient enrichment in Iowa’s surface waters.

(Why is it important to address this issue with education?  What are the desired changes?)

Growers and agronomic advisors need to know the research of better soil nutrient management in order to maximize yield potential, at the same time reducing the risk of additional off-site movement of nutrients than cause problems for surface water quality.

(Outputs: activities, numbers reached, publications, products)

Two workshops were held, one in 2010, another in 2011, to teach the basics of soil fertility for crop producers. This one day workshop was designed to look closely at the basics of P and K in crop production, how recommendations are developed, calculate the rates of application, talk about the difference between pounds and units, and discuss different management theories. We then discussed  N management, forms, how loss occurs. and N management tools. Reviewing soil lime needs followed, with a review of research results to lime applications, and a discussion and practice problems on ECCE calculations for different forms of lime. At the end of the day we spent a little time on micronutrient responses in Iowa. A limit of 40 was set for each year, and we trained over 80 in that time period.

RESULTS (Outcomes:  specific changes that occurred in Learning, Actions, Conditions; how outcomes were measured)

A survey was sent to 79 past participants in the workshop, with 36 returned (46%). Surveys were sent 1 to 2 years after workshop attendance. All respondents felt more confident discussing fertilizer application rates and recommendations. 92% are now more involved in making their own recommendations. 61% have changed fertilizer application rates based on what they learned. 33% lowered application rates but maintained yields, 42% increased fertilizer rates but increased yields, and one indicated they applied the same amount of fertilizer, they just shifted which areas to which fertilizer was applied. 81% indicated they wanted to meet again to answer more questions about managing soil fertility.

Desired Changes

Learning – better understanding of responsiveness of soil to fertilizer addition – or what happens when it is not added, depending on soil test levels.
Actins – better decisions made and changed application rates based on knowledge of soil tests.
Conditions – matching soil fertility to needs and reducing excess in soils reduces the possibility for off-site movement of P to surface waters, also proper N management reduces risk of N to groundwater.

Extension Lead(s)
(name, position, counties served, contact information)

Joel DeJong, NW Iowa Extension Field Agronomist - Lead
John Sawyer
Antonio Mallarino

Your Position

­­­­­___X__Field                                        __X___Campus                         _____Both

POW # and Team

 ­­­­­__x___100 Corn and Soybean Production and Protection
­­­­­_____ 110 Dairy
­­­­­_____ 120 Farm and Business Management
­­­­­_____ 130 Horticulture: Commercial and Consumer
­­­­­_____ 140 Iowa Beef Center
­­­­­_____ 150 Iowa Pork Industry Center
­­­­­__x___ 160 Natural Resources and Stewardship

ANR Priority (select all that apply)

­­­­­__x___Global Food Security and Hunger
­­­­­_____Regional Food Systems
­­­­­___x__Natural Resources & Environmental Stewardship
­­­­­_____Food Safety
­­­­­_____Sustainable Energy – Biofuels & Biobased Products
­­­­­_____Climate Change

Knowledge Areas: (USDA categories)


Continuing Story

_____ No                __X___  Yes (If continuing, what story?)
2010 – had a similar title.

Major Partners or Collaborators


Where story took place
(Region, campus, multi-regional)

NW Iowa regional meetings.

Fiscal Year

2010 & 2011

Multi-state or Integrated (Ext + Research)


Funding Source

Self-funded by workshop participants


Soil fertility, fertilizer management



Page last updated: February 7, 2012
Page maintained by Julie Honeick,