GEO-SPATIAL DATA AND INFORMATION
ENVIRONMENTAL MANAGEMENT [ASSESSMENT AND MONITORING]
GLOBAL ENVIRONMENTAL CHANGE

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

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

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

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

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

The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

FAO declines all responsibility for errors or deficiencies in the database or software or in the documentation accompanying it, for program maintenance and upgrading as well as for any damage that may arise from them. FAO also declines any responsibility for updating the data and assumes no responsibility for errors and omissions in the data provided. Users are, however, kindly asked to report any errors or deficiencies in this product to FAO.

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

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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 frost definitions
Radiation frost
Advection frost
Classification of protection methods
Geographical assessment of frost damage to crops
Economic importance of frost damage
History of frost protection

CHAPTER 2 - RECOMMENDED METHODS OF FROST PROTECTION

Introduction
Crop sensitivity and critical temperatures
Passive protection

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

Active protection

Heaters
Wind machines
Helicopters
Sprinklers

Over-plant conventional sprinklers
Targeted over-plant sprinklers
Sprinklers over covered crops
Under-tree conventional sprinklers
Under-plant microsprinklers
Trickle-drip irrigation
Under-plant sprinklers with heated water

Surface irrigation

Flood irrigation
Furrow irrigation

Foam insulation
Combination methods

Under-plant sprinklers and wind machines
Surface irrigation and wind machines
Combination of heaters and wind machines
Sprinklers and heaters

Forecasting and monitoring
Probability and risk
Economic evaluation of protection methods
Appropriate technologies

CHAPTER 3 - MECHANISMS OF ENERGY TRANSFER

Mass and energy in the air
Energy balance

Sign convention

Humidity and Latent heat

Sensible heat
Conduction - Soil heat flux
Radiation
Latent heat flux

Additional resources on energy balance

CHAPTER 4 - FROST DAMAGE: PHYSIOLOGY AND CRITICAL TEMPERATURES

Introduction
Cell injury
Avoidance, tolerance and hardening
Plant sensitivity
Types of damage and critical temperatures
Annual and biennial crops
Perennial crops
Fruit trees
Grapes and wine grapes
Other small fruits
Citrus fruits

CHAPTER 5 - FROST FORECASTING AND MONITORING

Value of frost forecasts
Predicting minimum temperatures
Calibrating mesoscale to microscale forecasts
A simple minimum temperature forecast model
A simple temperature trend forecast model
Forecast worksheet
Wet-bulb worksheet
Input worksheet

Predicting air temperature trend
Predicting wet-bulb temperature trend
Deciding whether to start sprinklers
Updating with current temperature observations
Documentation of the FTrend.xls application
Alarms and monitoring weather during a frost night

CHAPTER 6 - PASSIVE PROTECTION METHODS

Site selection and management

Cold air drainage
Slope and aspect
Soil type and water content

Plant selection
Canopy trees
Plant nutrition management
Proper pruning
Cooling to delay bloom
Chemicals to delay bloom
Plant covers
Avoiding soil cultivation
Irrigation
Removing cover crops
Soil covers

Plastic soil covers
Organic Mulches

Painting trunks
Trunk wraps
Bacteria control
Seed treatment with chemicals

CHAPTER 7 - ACTIVE PROTECTION METHODS

Heaters

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

Wind machines

Conventional wind machines

Theory of operation
Starting and stopping

Vertical flow wind machines
Helicopters

Sprinklers

Basic concepts
Over-plant sprinklers
Conventional rotating sprinklers

Starting and stopping
Application rate requirements

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

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

Surface irrigation

Flooding
Furrow irrigation

Foam insulation
Foggers
Combination methods

Wind machines and under-plant sprinklers
Wind machines and surface irrigation
Wind machines and heaters
Sprinklers and heaters

CHAPTER 8 - APPROPIATE TECHNOLOGIES

Introduction
Common protection methods
Passive methods
Active methods
Appropriate technology summary
Frost protection survey respondent comments

Argentina (NE of Buenos Aires)
Greece
Jordan
Mexico (Chihuahua)
Zimbabwe

REFERENCES

APPENDIX 1 - PREFIXES AND CONVERSION FACTORS

Prefixes
Conversion factors

Temperature
Pressure (air pressure, vapour pressure)
Wind speed
Radiation

Physical properties

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

APPENDIX 2 - CONSTANTS

APPENDIX 3 - HUMIDITY CALCULATIONS

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