An Exercise In Precision Agriculture

Module 7
Variable-Rate Application Technologies

Introduction

Variable-Rate Fertilizer: The ability to control the application of nutrients to crop production units is one of the essential components of precision farming. Application uniformity is a major concern with traditional field-average application approaches. The significance of uniformity to variable-rate granular application systems increases. Application errors are compounded by lag-times in material delivery to the spreading device and with metering rate changes. Combining these errors with positioning errors can lead to significant differences in actual versus expected application rates. This educational unit will focus on discussions of the control and delivery elements of variable-rate fertilizer application equipment. Implications of each component on application accuracy will be demonstrated.

Variable-Rate Herbicide Application: Placement of herbicides in precision farming must be treated from two perspectives, soil and folier applied herbicides. Variable-rate application may be of value for those compounds which are affected by changes in soil parameter such as pH, texture, or organic matter content. Application errors and lag-times in herbicide concentrations changes at the nozzle tips affect the ability of boom-type sprayers to produce the desired application results. For the folier applied herbicides the ability to map weed competition, select appropriate compounds, or apply two or more compounds simultaneously have profound environmental and economic implications. Plumbing and control elements of variable-rate herbicide application equipment will be discussed in this educational unit.

 

Case Studies

  1. Variable-Rate Herbicide Application

  2. Economics of Variable-Rate Herbicide Application

  3. Variable-Rate Fertilizer Application

  4. Economics of Variable-Rate Fertilizer Application

Slide Presentations

  1. Variable-Rate Seeding

  2. Variable-Rate Fertilizer: Control System

  3. Variable-Rate Fertilizer: Application Accuracy

Exercises

Exercise 1 Grid Sampling Techniques Learn the procedure of referencing soil samples to a geographic location with the GPS.
Exercise 2 Variable Rate Fertilizer Application Download a spreadsheet which guides the user through the variable rate application of soil nutrients.
Exercise 3 Input Cost Download a spreadsheet which illustrates the economics between fixed rate application and variable rate application of nutrients.

Return to Main Module Index