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GEO-SPATIAL DATA AND INFORMATION
ENVIRONMENTALMANAGEMENT [ASSESSMENT AND MONITORING]
GLOBAL ENVIRONMENTALCHANGE

Ice accumulation from the use of under-tree sprinklers inNorthern California(photographer: Richard L. Snyder)

Apple flowers damaged by frost depicting darkened petalsa few days after a frost event in an orchard in Northern Portugal(photographer: António Castro Ribeiro)

Ice accumulation from operation of targeted sprinklersover grapevines(photographer: Robert Corrella)

Background image in this page
Illustrationelaborated from "L'Encyclopédie Diderot et D'Alembert"

The conclusions given in this report are consideredappropriate at the time of its preparation. They may be modified in the light offurther knowledge gained at subsequent stages of the project.

The designations employed and the presentation of material inthis information product do not imply the expression of any opinion whatsoeveron the part of the Food and Agriculture Organization of the United Nationsconcerning the legal or development status of any country, territory, city orarea or of its authorities, or concerning the delimitation of its frontiers orboundaries.

FAO declines all responsibility for errors or deficiencies inthe database or software or in the documentation accompanying it, for programmaintenance and upgrading as well as for any damage that may arise from them.FAO also declines any responsibility for updating the data and assumes noresponsibility for errors and omissions in the data provided. Users are,however, kindly asked to report any errors or deficiencies in this product toFAO.

ISSN 1684-8241
ISBN: 92-5-105328-6

All rights reserved. Reproduction and dissemination ofmaterial in this information product for educational or other non-commercialpurposes are authorized without any prior written permission from the copyrightholders provided the source is fully acknowledged. Reproduction of material inthis information product for resale or other commercial purposes is prohibitedwithout written permission of the copyright holders.

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© FAO 2005

CONTENTS

Foreword
Abstract
Acknowledgements
Acronyms used in the text
List of principal symbols
Executive summary

CHAPTER 1 -INTRODUCTION

Overview
Freeze and frostdefinitions
Radiation frost
Advection frost
Classification of protectionmethods
Geographical assessment of frostdamage to crops
Economic importance of frostdamage
History of frostprotection

CHAPTER 2 - RECOMMENDED METHODS OFFROST PROTECTION

Introduction
Crop sensitivity and criticaltemperatures
Passive protection

Site selection andmanagement
Cold air drainage
Plant selection
Canopy trees
Plant nutritionmanagement
Pest management
Proper pruning
Plant covers
Avoiding soilcultivation
Irrigation
Removing cover crops
Soil covers
Trunk painting and wraps
Bacteria control

Active protection

Heaters
Wind machines
Helicopters
Sprinklers

Over-plant conventionalsprinklers
Targeted over-plant sprinklers
Sprinklers over covered crops
Under-tree conventionalsprinklers
Under-plant microsprinklers
Trickle-drip irrigation
Under-plant sprinklers with heatedwater

Surface irrigation

Flood irrigation
Furrow irrigation

Foam insulation
Combination methods

Under-plant sprinklers and windmachines
Surface irrigation and windmachines
Combination of heaters and windmachines
Sprinklers and heaters

Forecasting andmonitoring
Probability and risk
Economic evaluation of protectionmethods
Appropriate technologies

CHAPTER 3 - MECHANISMS OF ENERGYTRANSFER

Mass and energy in theair
Energy balance

Sign convention

Humidity and Latent heat

Sensible heat
Conduction - Soil heatflux
Radiation
Latent heat flux

Additional resources on energybalance

CHAPTER 4 - FROST DAMAGE: PHYSIOLOGYAND CRITICAL TEMPERATURES

Introduction
Cell injury
Avoidance, tolerance andhardening
Plant sensitivity
Types of damage and criticaltemperatures
Annual and biennialcrops
Perennial crops
Fruit trees
Grapes and wine grapes
Other small fruits
Citrus fruits

CHAPTER 5 - FROST FORECASTING ANDMONITORING

Value of frost forecasts
Predicting minimumtemperatures
Calibrating mesoscale to microscaleforecasts
A simple minimum temperature forecastmodel
A simple temperature trend forecastmodel
Forecast worksheet
Wet-bulb worksheet
Input worksheet

Predicting air temperaturetrend
Predicting wet-bulb temperaturetrend
Deciding whether to startsprinklers
Updating with current temperatureobservations
Documentation of the FTrend.xlsapplication
Alarms and monitoring weather during afrost night

CHAPTER 6 - PASSIVE PROTECTIONMETHODS

Site selection andmanagement

Cold air drainage
Slope and aspect
Soil type and watercontent

Plant selection
Canopy trees
Plant nutritionmanagement
Proper pruning
Cooling to delay bloom
Chemicals to delay bloom
Plant covers
Avoiding soilcultivation
Irrigation
Removing cover crops
Soil covers

Plastic soil covers
Organic Mulches

Painting trunks
Trunk wraps
Bacteria control
Seed treatment withchemicals

CHAPTER 7 - ACTIVE PROTECTIONMETHODS

Heaters

Theory of operation
Smoke effects
Heater requirements
Heater placement andmanagement
Liquid-fuel heaters
Propane-fuel and natural gas-fuelheaters
Solid-fuel heaters
Mobile heaters

Wind machines

Conventional windmachines

Theory of operation
Starting and stopping

Vertical flow windmachines
Helicopters

Sprinklers

Basic concepts
Over-plant sprinklers
Conventional rotatingsprinklers

Starting and stopping
Application rate requirements

Variable rate sprinklers
Low-volume (targeted)sprinklers
Sprinkling overcoverings
Under-plant sprinklers

Conventional rotatingsprinklers
Microsprinklers
Low-volume (trickle-drip)irrigation
Heated water

Surface irrigation

Flooding
Furrow irrigation

Foam insulation
Foggers
Combination methods

Wind machines and under-plantsprinklers
Wind machines and surfaceirrigation
Wind machines andheaters
Sprinklers and heaters

CHAPTER 8 - APPROPIATETECHNOLOGIES

Introduction
Common protectionmethods
Passive methods
Active methods
Appropriate technologysummary
Frost protection survey respondentcomments

Argentina (NE of BuenosAires)
Greece
Jordan
Mexico (Chihuahua)
Zimbabwe

REFERENCES

APPENDIX 1 - PREFIXES AND CONVERSIONFACTORS

Prefixes
Conversion factors

Temperature
Pressure (air pressure, vapourpressure)
Wind speed
Radiation

Physical properties

Properties of Water
Properties of gases atP_b = 101.3 kPa barometric pressure
Black body emittance (Wm^-2) as a function of subzero temperature (°C)

APPENDIX 2 -CONSTANTS

APPENDIX 3 - HUMIDITYCALCULATIONS

FAO ENVIRONMENT AND NATURALRESOURCES SERIES

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