FERTILIZER AND PLANT NUTRITION BULLETIN 13
	Use of Phosphate Rocks for Sustainable Agriculture Technical editing by F. Zapata Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture Vienna, Austria R.N. Roy Land and Water Development Division FAO, Rome, Italy A joint publication of the FAO Land and Water Development Division and the International Atomic Energy Agency
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2004
	Table of Contents

COVER PHOTOGRAPHS

Phosphate rock ore and mining in Khouribga, Morocco.
Abdelatif Belmehdi, IMPHOS, Morocco.

Phosphate rock broadcast application.
Efficient fertilizer use, 1988, FAO, Rome.
Maize crop. Nicaragua. FAO/15962/L. Dematteis.

ISSN 0532-0488
ISBN 92-5-105030-9

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

Applications for such permission should be addressed to:
Chief
Publishing Management Service
Information Division
FAO
Viale delle Terme di Caracalla, 00100 Rome, Italy
or by e-mail to:
copyright@fao.org

© FAO 2004

Contents

ACKNOWLEGEMENTS

PREFACE

CONTRIBUTING AUTHORS

LIST OF ABBREVIATIONS AND ACRONYMS

EXECUTIVE SUMMARY

1. INTRODUCTION

Phosphorus in the soil-plant system
The need for sustainable development
Addressing the P constraint in tropical acid soils
Use of phosphate rocks in industry and agriculture

Phosphate rocks as raw materials for P-fertilizer manufacturing
Phosphate rock for direct application in agriculture
Historical account of the use of phosphate rocks in agriculture

The bulletin

2. WORLD PHOSPHATE DEPOSITS

World phosphate rock production
World phosphate rock reserves and resources
Future trends in world phosphate rock production

3. CHARACTERIZATION OF PHOSPHATE ROCKS

Phosphate rock mineralogy

Sedimentary apatites
Igneous apatites
Other minerals in PRs

Phosphate rock solubility tests

Apatite solubility

Classification of phosphate rocks based on solubility
Characterization methods

4. EVALUATION OF PHOSPHATE ROCKS FOR DIRECT APPLICATION

Phosphate-rock solubility tests

Solubility measurements using conventional chemical techniques
Kinetics of long-term PR dissolution
PR reactivity scales and crop yield response
Measurement of exchangeable P from PR by radioisotopic techniques

Reactions between phosphate rocks and soil

Soil incubation
Liming effect of PRs

Greenhouse tests

Comparison of PRs with standard fertilizers
Effect of time
Relationship between PR solubility and crop P uptake

Field evaluation

5. FACTORS AFFECTING THE AGRONOMIC EFFECTIVENESS OF PHOSPHATE ROCKS, WITH A CASE-STUDY ANALYSIS

Factors affecting the agronomic effectiveness of phosphate rocks

Reactivity of PRs
Soil properties
Climate conditions
Crop species
Management practices

Case studies

Mali
Madagascar
India
Indonesia
New Zealand
Latin America

6. SOIL TESTING FOR PHOSPHATE ROCK APPLICATION

Soil phosphorus reaction and soil testing
Conventional soil tests

Bray I test
Bray II and Mehlich I tests
Olsen test

Recently developed soil tests

Iron-oxide-impregnated paper test
Mixed anion and cation exchange resins
Isotopic ³²P exchange kinetic method

7. DECISION-SUPPORT SYSTEMS FOR THE USE OF PHOSPHATE ROCKS

The need for a decision-support system for phosphate rocks
Conceptual basis for building a PR-DSS
Different types of DSS to predict PR performance

Mechanistic models
The combination of mechanistic and empirical models

Expert systems

The ‘RPR Adviser’ in Australia

Requirements for a global DSS for PR use

Creation of a database for PR reactivities
Creating a database of soils for PR use
Other requirements

Future developments

8. SECONDARY NUTRIENTS, MICRONUTRIENTS, LIMING EFFECT AND HAZARDOUS ELEMENTS ASSOCIATED WITH PHOSPHATE ROCK USE

Secondary nutrients in phosphate rock
Micronutrients in phosphate rock
Liming effect associated with PR use
Hazardous elements in phosphate rock

9. WAYS OF IMPROVING THE AGRONOMIC EFFECTIVENESS OF PHOSPHATE ROCKS

Biological means

Phospho-composts
Inoculation of seedlings with endomycorrhizae
Use of ectomycorrhizae
Use of phosphate solubilizing micro-organisms
Use of plant genotypes

Chemical means

Partial acidulation of phosphate rock

Physical means

Compacted PR with water-soluble phosphate products
Dry mixtures of PR with water-soluble phosphate fertilizers
Phosphate rock elemental sulphur assemblages

10. ECONOMIC FACTORS IN THE ADOPTION AND UTILIZATION OF PHOSPHATE ROCKS

Possible adoption and use of phosphate rock by end users
Cost of production, transport and distribution
Economic considerations and policies to support PR adoption

Pricing policy
Organizational policy
Agricultural product markets
Risk protection
Research and extension policy

Case studies of PR exploitation and use
Marketing of indigenous phosphate rocks for direct application

Latin America
Asia
Sub-Saharan Africa

Economic criteria in PR adoption and use - a case study on Venezuela

Agronomic evaluation and domestic market potential
Economics of PAPR production
Pilot-plant evaluation test
PAPR quality
The Moron PAPR plant
Raw materials and products

11. LEGISLATION AND QUALITY CONTROL OF PHOSPHATE ROCKS FOR DIRECT APPLICATION

Current legislation on phosphate rock for direct application
Associated issues

Total P₂O₅ content of PR

Solubility of phosphate rock

Expressing PR solubility
Free carbonate effect
Particle-size effect

Guidelines for legislation on DAPR

12. EPILOGUE

BIBLIOGRAPHY

FAO TECHNICAL PAPERS

BACK COVER

How to Order