soil salinity: causes and cures - university of...
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December 13, 2012 Soil Salinity by Les Henry 1
SOIL SALINITY:
CAUSES AND CURESby
Les Henry , Professor Emeritus
University of Saskatchewan
143 Tucker Cres, Saskatoon SK S7H3H7
Manitoba Agronomists Conference
Univ of Manitoba, Winnipeg
December 13, 2012
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• PROBLEM SOILS–Acid, Calcareous, True Alkali– Solonetz – have saline subsoil
• SOIL SALINITY–is not a SOIL problem–it is a WATER problem.
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Saline Soils : Causes
• What Salts - and measurement
• Basic Mechanism of Salinization
• Groundwater Flow Mechanisms
Saline Soils : Cures• Reclaiming Saline Soils
• Managing Saline Soils
• Precision Farming and Saline Soils
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December 13, 2012 Soil Salinity by Les Henry 6
THE SALTS - Solubility grams/liter @ 20C
HIGHLY SOLUBLE
CaCl2 - 427
MgCl2 - 353
MgSO4 - 300NaCl - 264
Na2SO4- 160
Slightly Soluble
CaSO4 - 2 (Gypsym)
Insoluble
CaCO3 - 0.01 (Lime)CaCO3+HCl CO2
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Measuring Soil Salinity - in lab
Saturated Paste - is gold standard
Non Saline 0-2 mS/cm ( or dS/m) OK
Slightly Saline 2-4 Sensitive plants affected
Moderately Saline 4-8 Most Ccrops affected
Severely Saline 8-16 Only tolerant plants survive
Very Severely Saline 16+ FORGET IT
Many Labs use 1:1 or 1:2 Extract or suspension
MAKE SURE YOU INTERPRET THE RIGHT DATA
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SOIL SALINITY IS A WATER PROBLEM
* Water Table High - Suction Lift
* Evaporation > precipitation
Sun is the driving force
MB Agric1975
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THINK
- Water Table High
- Evaporation > precipitation
- ??????????????
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TAKE HOME MESSAGE:
1. SOIL SALINITY CAUSED BY HIGH WATER TABLE
2. NEED EVAPORATION>PRECIPITATION. GROUNDWATER MOVEMENT REQUIREDTO MAINTAIN WATER TABLE IN DRY PERIODS
2. MUST KNOW GROUNDWATER MOVEMENT TO UNDERSTAND THE PROBLEM
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Mechanisms to Maintain High Water Table in Dry Times
* Side-Hill Seep ( rare in MB)
* Evaporitic( Bathtub) Ring around sloughs ( Common)
Artesian Discharge( Dominant)
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Evaporitic ( Bathtub) Ring
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EM = 35/24
Slough Bottom
NATIVE PRAIRIE: NEAR SASKATOON
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EM 150/105
Bathtub Ring
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GAME CHANGER:
MOOSE JAW- EXTENSION MEETING – LATE 1970S.
•SOIL SALINITY -BIG PROBLEM – NEED ALL DAY MEETING
•BROUGHT ALL THE BIG GUNS - ALL DAY
•END OF THE DAY: FARMER REACTION
“YOU TOLD US WHAT WE ALREADY KNEW IN LANGUAGE WE COULD NOT UNDERSTAND AND TOOK ALL DAY TO DO IT”
ON THE DRIVE HOME WE KNEW A DIFFERENT APPROACH WAS NEEDED
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1982-1994 -Field Studies
Dig a little Deeper- Think a little Broader
Earl Christiansen
Prof Soloninko
Paul BullockGraham Phipps
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Artesian Discharge: Dominant Mechanism in Sask.
Flowing Wells Common
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University of Saskatchewan : Goodale Farm
Head Above Ground1986 3.3 m 11 feet2002 2.4m 8 feet2010 4.3m 14 feet
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Piezometer Nests- How it all works pg 151 Henry’s Handbook
Water Table= a piezometer that just has water in. If not too deep a slotted pipe will show the water table.Wat
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Flowing and high water level wells
LAKE MANITOBA
FROM; RUTULIS, 1987 – GROUNDWATER WEST INTERLAKE
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PP AQUIFER PIEZOMETRIC LEVEL
SOIL SURFACE
From “ Springs in Southern MB” Rutulis, 1985
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YEAR
500m
504m
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MB Flowing wells and Springs
Saline Water
Fresh Water
Artesian Brine Springs – NaClSalt first MB Industry ~ 1800
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ARTESIAN DISCHARGE:
SLOW AND STEADY- WORKS 24 HOURS A DAY 365 DAYS A YEAR.
1 cm/year for 10,000 years = 100 m of water
Reference : Canadian Journal of Soil Science 1985; Volume 65 pages 749-768.
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WATER TABLE IS NOT STATIC ;
IT VARIES GREATLY IN SPACE AND TIME
a Manitoba example.......
December 13, 2012 Soil Salinity by Les Henry 26From MB Soil Survey Report #17 P la P Michalyna & Smith, 1972
1m1
2m1
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MORAL OF THE STORY:
If you do not know where water table is
MEASURE IT
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Dutch auger –2 extensions 2m well July 9 2012
Elevation ~2030 FASL
Water Table: Rain
July 9 1.17mJuly18 1.28m Jul16 23mm
July21 1.46mJuly26 1.58mAug 2,9,13 1.78m Aug27 1.78m
NW22-32-3W3 Contours by Farmer’s Edge
2” PVC 3mCentral Vac
Saline Soils : Cures• Reclaiming Saline Soils
• Managing Saline Soils
• Precision Farming and Saline Soils
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December 13, 2012 Soil Salinity by Les Henry 30
RECLAIMING SALINE SOILSKelley,W.P. 1937. The reclamation of alkali soils. Calif. Ag Exten Bull #717.
* Ca + Mg Salts - Drain + Leach
* Na Salts - Saline-Sodic
Add gypsum, drain and leach
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RECLAIMING SALINE SOILS1. Drainage
PLUS2. Leaching
3. If in doubt, See 1 PLUS 2
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HARD WATER MAKES SOFT LAND
SOFT WATER MAKES HARD LAND
*Most of our saline soils have ‘hard’salts so gypsum is not required.
* If we have hard water aquifer can use that water to leach
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Tile Drainage Alone = No Solution
Southern AlbertaCirca 1989
Land had been drained so OK for busOOPs
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U of S Goodale Farm
Leaching Alone
Looks Good Short Term
BUT ??
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Water Table:
Soon at
Soil
Surface
1988 no rain ; no irrigation = no crop
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When a soil is at Field Capacity moisture and we add ONE INCH of rain the effect on the water table rise will be:
* 6 Inches for a loamy sand soil
*One FOOT for a Clay soil
Note: Above rule of thumb is NOT in Henry’s Handbook
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Outlook : CSIDC; Terry Hogg , Laurie Tollefson
Drainage + Leaching = Long Term Solution
1986 White Crusts – Tile installed – Then lots & lots of irrigation .
Terry Hogg
1990
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MANAGING SALINE LAND:
SELL IT IN THE WINTER TIME
July – Same Color
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MANAGING SALINE LAND:• Crop Rotation - Avoid Summerfallow• Crop Selection
– Barley , Canola most tolerant– Pea, Bean least tolerant– Forages - Now have AC SaltlanderAAFC Swift Current Current -Salt Tolerance Testing Facility:Harold Steppuhn
Durum & Soft Wheat > CPS and CWRSYEAR A BIG FACTOR : RAIN IN MAY -
SALTS GO AWAY
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MANAGING SALINE LAND:
For severely salt affected parcels of land the only practical cropping solution is:
PLANT IT DOWN TO SALT TOLERANT GRASS
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MANAGING SALINE LAND:
There are no quick fixes-
Nothing you are going to spray or spread
NOTHING
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Alfalfa and the Water Table
Paul Brown
USDA
Montana
1970s-1980s
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SALINE SOILS AND PRECISION FARMING
• Saline soils are very fertile - i.e. many nutrients. High soil test nitrate :
12-24” often saline
• Map saline soils on a quarter and fertilizer to add = ZERO
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Mapping Saline Soils : Do Your Homework
Much info about NW22 from office*Soil Maps - Framework to think in
*Topographic maps, waterwell maps , geology maps
*Air Photos and Satellite Imagery
- Manitoba Agri-Map and Google Earth
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X= Salinized
HAMIOTA
OSBORNE CLAY- SALINE 1950s soil maps
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Mapping Salinity with EM38
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www.flysask.ca 2008 photo Les Henry Home Quarter
SalineTW & SLWgrass 2011
Broadcast 2010
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TAKE HOME MESSAGE:1. SOIL SALINITY CAUSED BY HIGH WATER TABLE
2. SALINIZATION OCCURS IN TIME PERIODS WHEN EVAPORATION EXCEEDS PRECIPITATION
2. MUST KNOW GROUNDWATER MOVEMENT TO UNDERSTAND THE PROBLEM
3. THERE IS NO SPRAY OR SPREAD SOLUTIONPLANT IT DOWN
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THE END
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