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ISU Extension Logo

Northwest Iowa Crop Growth Simulation Page
by Todd Vagts
ISU Extension Crops Specialist
Counties Served:  Carroll, Calhoun, Crawford, Ida, Monona, Pocahontas and Sac.

Home | ISU Extension | IA State University
Newsletters | Crop Modeling | Special Topics | Weather Data | Subsoil H20 | PDF Info
Model Run Data for
Corn and Soybean Emergence Dates
Growth Parameters: Corn | Soybean (05 Data not yet available)
Yield Potential Trend (averaged across planting date) 2005 data not yet available
Yield Potential by Planting Date 2005 data not yet available
Crop Growth Simulation and Crop Management

Crop Management Challenges

Agricultural producers, consultants, service providers, and industry representatives are faced with crop management and cropping system decisions throughout the growing season.  The need of the agricultural person to manage and predict a crop's behavior over a wide range of planting dates, geographies and crops has become increasingly important as the need (value) for good, timely decisions and a decision making process has greatly increased.  Use of crop simulation models incorporating local climatic conditions with management operations may increase the agricultural personís ability to make more timely and educated decisions. 

From the Lab to the Field
Scientific crop growth simulation models have traditionally been used to address research problems, answer questions and most importantly, to increase knowledge on crop growth, development and yield.  The time has finally arrived in which crop modeling tools are increasingly being deployed in producer fields to help address questions and problems on a larger, farm scale size.  The full potential and value of crop models have not yet been realized in production agriculture.

In-Season Management Decisions affect Yield
The emphasis in production agriculture has been placed on attaining the maximum yield possible, or obtaining the most economical yield.  What is often not well understood is that yield is determined during the growing season when critical crop management decisions are being made on a daily basis.  Final crop yield is often dependent on the quality and timeliness of the management decisions.   Tools that gather and display crop development progress and weather information can aid the agricultural person in making accurate and timely decisions and can greatly enhance production and profitability.

Modeling Phenology and Yield
he ability of a crop simulation model to predict crop development is inherently more accurate than its ability to predict end grain yield.  This is simply due to the fact that most plants can be effectively characterized for growth based on accumulated growing degree days, which is easy to measure and calculate and is less affected by other environmental influences.   Furthermore, the accuracy of the modelís output decreases as the season progresses due to the accumulation of errors through time.  Crop yield is an accumulation of several predictions of physiological processes through time and inherently has the most errors associated with it.

Phenology and Yield and the Environmental
Local environment is a large, uncontrollable factor in determining crop yield and quality in any given year.  Likewise, local soil characteristics, pest factors, crop selection and management also play a large, yet controllable role in localized yield.  But due to the amazingly large number of variables, simulating these factors over a large geographical area is not feasible or practical.  Therefore the data presented in the following tables generalizes or excludes local "controllable or management" factors; and therefore the sole influencing variable as the season progresses is environment, mainly temperature, rainfall and solar radiation.


Model Runs for Ames, Castana, Kanawha and Sutherland

Todd Vagts
Iowa State University Extension
Field Crops Specialist
1240 D. Heires Avenue 
Carroll, IA 51401 
Office: 712-792-2364; Cell: 712-249-6025;  Fax: 712-792-2366

For questions or comments please respond to

This page last updated on 05/18/05

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