Precision Agriculture & GPS

Introduction

• Precision farming:• managing each crop production

input on a site specific basis.• Example inputs:

–fertilizer --lime

–pesticides -- seed

Objectives of Precision Farming

• Reduce waste

• Increase profit

• Maintain environment

Comparison• Pre-mechanization:• Farmers dealt with each seed &

plant

• Post-mechanization:• Farmers dealt with entire fields

Variable Rate Application

• Applying different amounts of input while going across field

Variable Rate Technology

• Tools and equipment that allows for variable rate application

Variability in the Field

• Soil fertility• Moisture content• Soil texture• Topography• Pest population• pH

Fast changers:

• nitrate level

• moisture content

• pest population

Slow changers:

• topography

• texture

• pH

Fertilizers

• 97% of corn acres applied with N

• ~25% cash production costs

• Consider environmental impact

Pesticides

• $7 billion spent annually

• 98% of corn & soybean acres

• Environment is concern

Seed

• 1900 -- 1 farmer fed 8 people• 1990 -- 1 farmer feeds >100

people

• We can change plant population as we plant

Components of Precision Farming

• Tillage - depth & residue

• Planting - seed rate & depth

• Spraying - certain area

• Crop scouting - problem area

• Harvesting - yield monitor

Where on Earth are We?

• Dead reckoning

• Land-based positioning

• Satellite-based positioning

Dead Reckoning

• Uses starting point

• Speed

• Travel time

• Number of passes to determine location

Land-Based Positioning

• Uses radio towers

• Must have three towers

Satellite-Based Positioning

• AKA

• Global Positioning System

• GPS for short

GPS

• Constellation of satellites

• Developed by Department of Defense

• Used 24 hrs./day anywhere on Earth

Uses

• Military

• Industrial

•Commercial•Civilian

Segments of GPS

• Space

• User

• Control

Space

• 24 satellites

• 12,000 miles above Earth

• Orbit twice daily

• Always have at least 4 satellites in view

• “In view” = above horizon

• Each satellite sends & receives radio signals

• Radio signals travel ~183,000 miles per second

• Satellites equipped with atomic clock for accuracy

User Segment

• GPS Units & Receivers

• Free of charge usage of signals

Control Segment

• Track & monitor satellites

• Master Control Station - AFB in Colorado Springs