Soil Plan: A Computerized Fertilizer and Limestone Recommendation Program

Illinois Fertilizer Conference Proceedings
January 29-31, 1996

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Soil Plan: A Computerized Fertilizer and Limestone Recommendation Program

R.G. Hoeft¹

Abstract

Soil Plan, a computerized fertilizer and limestone recommendation program has been developed that will provide the same recommendations one could obtain by following the information provided in the Illinois Agronomy Handbook. The advantage of the program is that it does the calculating and thinking for you. It makes sure you do not forget to take into account important management factors that affect fertilizer recommendations. The program provides recommendations for each field and combines those recommendations into an overall fertilizer program for the farm.

Introduction

Soil Plan was developed to provide producers and their advisers a computerized soil fertility recommendation system based on research results collected from Illinois soils. This program utilizes soil test data, cropping history, cropping intentions, soil types and availability of livestock wastes to provide a fertility recommendation designed to provide optimum crop yield.

Characteristics of each Illinois soil type that influence fertilizer recommendations are resident in the program. By specifying soil type, these characteristics will be utilized to adjust recommendations accordingly.

A unique feature of the program is its ability to assist users in allocating fertilizer budgets. It calculates the expected fertilizer cost for each field and a total for the farm based on the prices you expect to pay for each element that year. It also provides an estimate of the relative yield potential if any of the nutrients are not applied. This can be an important management tool in prioritizing where limited fertilizer resources will be used.

Soil Plan provides an estimate of nitrogen loss potential for each soil and suggests management techniques to consider. While the program does not utilize micronutrient soil test data, it does utilize soil pH to flag fields where micronutrient problems may occur. The message associated with the flag describes the micronutrient deficiency and provides a suggested correction technique.

The final report provides a map for each nutrient for each field, identifying the areas with similar recommendations that should be grouped together. This map could be used as a guide to spreading fertilizer on a site-specific basis. Or if one wants, the general field recommendation can be used. Because all the input data are stored, one can simply re-enter the program next year, update the cropping plans, and obtain a new recommendation.

Hardware and Software Requirement

While the program can be run on a 386 personal computer, it will operate more efficiently on a 486-25mhz or larger personal computer. The computer should have a hard disk drive with a minimum of 4 megabytes of available storage space and it should have 4 megabytes of memory installed (8 megabytes is recommended). Software requirements include MS-DOS Version 5.0 and MS-Windows 3.1 or higher.

Input Requirement

The first screen identifies the farm by name and location. The location entry is used to describe the location of the farm either by legal description or by farm name. The screen requires the identification of the county in which the farm is located. In later screens the county name is utilized to create a soil type menu for ease of selection of the soil types in the field. Fertilizer and lime price information is requested to allow the program to calculate a total cost for the recommendation for each field and farm.

Separate information is required for each field within the farm. This information includes a field name, tillage depth, soil type, acres, crop to be grown along with the proven yield, previous crop and its associated yield, and crop to be grown in the second year. If the second year crop is designated, the program will give a two year recommendation. If the second year crop is not designated, the recommendation will be for the coming year only. Users of the program have an opportunity to utilize the soil type menu to select specific soil types for the field. If that information is not available, the program will allow the user to identify the area within the county where the field is located and then utilize the general soils information in making the recommendation. The field screen also asks for information related to manure application including type of livestock, rate of application, and form of manure (liquid or dry). If the producer has an analysis of the manure supply, that information can be entered into the data base and will be utilized in the calculations. If such analysis is not available, the program
will utilize tabled manure values. Expected crop yield information is utilized to calculate crop nutrient removal. Entry of a crop yield value that is excessive for the particular soil type will result in a warning signal. The program will allow use of the entered value, but draws attention to the fact that the yield selected may be excessive relative to the long term expected yield of that soil type.

A table has been created to allow the user to record past cropping history and fertilizer and manure use. This data is not utilized in the recommendation program, but creates a long term record for the user.

Soil test information for pH, P, and K are required. The pH value must be given as water pH, the P value must be Bray P,, and the K value must be exchangeable K. Both P and K must be reported in pounds per acre.

Reports:

The program will utilize the input information to create a field by field recommendation and will then combine that into a farm recommendation. Recommendations are first created for each sample site in the field and then combined into areas of similar recommendations within a field. A map is printed that could be used to develop a site specific recommendation system.

An example of a print out of the information is provided in five image pages (1, 2, 3, 4, and 5). Note that the first image provides field by field recommendations along with a total cost for the field and for the farm. In addition, the first image provides an estimate of the yield potential relative to the expected for that soil type if one of the nutrients is not applied.