This guidelines publication is an outcome of a FAO Consultation on "Water, Soil and Crop Management Relating to the Use of Saline Water" held in 1989 in Rome. A number of ideas and the conceptual framework of the guidelines were developed at this Consultation. The authors wish to acknowledge the resource persons of the consultation, namely Messrs. I.P. Abrol (India), A. Hamdy (Italy), A. Meiri (Israel) and A.H.M. Rady (Egypt) who have contributed to this publication through the Expert Consultation.
A good part of the research findings reported in these guidelines has come from the United States Salinity Laboratory, Riverside, California, and the authors gratefully acknowledge the staff of the Laboratory for their outstanding contribution.
The authors wish to express their gratitude to Mr. S.F. Scott, Chief, Water Resources, Development and Management Service, and Mr. R. Brinkman, Chief, Soil Resources, Management and Conservation Service, for their support and encouragement in the preparation of the guidelines. A number of people have reviewed the document and proofread the text; the authors are grateful to them.
Thanks are also due to Ms. C.D. Redfern for her assistance in the preparation of the final camera-ready text and to Mr. D. Mazzei for the revision of the illustrations.
It is hoped that the guidelines will be useful to the many research and extension workers and the farmers who currently use, or will use in the future, the largely untapped resource of "saline water" for agriculture in a sustainable manner.
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USEFUL CONVERSION FACTORS AND FORMULAS | |
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TDS (mg/l) » EC (dS/m) × 640 |
for EC between 0.1 and 5.0 dS/m |
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TDS (mg/l) » EC (dS/m) × 800 |
for EC<5.0 dS/m |
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TDS (Ibs/ac » ft) = TDS (mg/l) × 2.72 |
|
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TDS (tons/ac » ft) = TDS (mg/l) × 0.00136 |
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sum of cations/anions (meq/l) » EC (dS/m) × 10 |
for EC between 0.1 and 5.0 dS/m |
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log cations/anions (mmolc/l) » 0.955 + 1.039 log EC (dS/m) | |
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log total soluble salts (mmolc/l) » 0.990 + 1.055 log EC (dS/m) | |
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ionic strength (mol/l) » EC (dS/m) × 0.0127 | |
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osmotic pressure (atm) » EC (dS/m) × 0.40 for EC between 3 and 30 dS/m | |
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List of abbreviations | |
|
SAR |
= sodium adsorption ratio |
|
EC |
= electrical conductivity |
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ECiw |
= electrical conductivity of irrigation water |
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SARsw |
= sodium adsorption ratio of soil water |
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dS/m |
= deciSiemens per metre |
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mmolc/l |
= millimol per litre |
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ECe |
= electrical conductivity of soil saturated extract |
|
TDS |
= total dissolved soilds |
|
mg/l |
= milligrams per litre |
|
BCM |
= billion cubic metres |
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MCM |
= million cubic metres |
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ESP |
= exchangeable sodium percentage |
|
Yr |
= relative yield |
|
T |
= tolerant crop |
|
MT |
= moderately tolerant crop |
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MS |
= moderately sensitive crop |
|
S |
= sensitive crop |
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g/m3 |
= grams per cubic metre |
|
RSC |
= residual sodium carbonate |
|
EC*e |
= water uptake weighted electrical conductivity of soil saturation extract |
|
p |
= osmotic potential |
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p * |
= water uptake weighted osmotic potential |
|
adj. SAR |
= adjusted sodium adsorption ratio |
|
t |
= metric water potential |
|
|
= total water potential |
|
|
= mean salt concentration |
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Viv |
= volume of infiltrated irrigation water |
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Vdw |
= volume of drainage water |
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LF |
= leaching fraction |
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Ciw |
= salt concentration of irrigation water |
|
Cdw |
= salt concentration of drainage water |
|
|
= mean metric water potential |
|
f f |
= total water potential at any given point for irrigation scheduling |
|
kPa |
= killiopascal |
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pCO2 |
= partial pressure of carbon dioxide (pascal Pa) |
