soil salinity: causes and cures - university of...

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.


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



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


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


SOIL SALINITY IS A WATER PROBLEM

* Water Table High - Suction Lift

* Evaporation > precipitation

Sun is the driving force

MB Agric1975


THINK

- Water Table High

- Evaporation > precipitation

- ??????????????


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


Mechanisms to Maintain High Water Table in Dry Times

* Side-Hill Seep ( rare in MB)

* Evaporitic( Bathtub) Ring around sloughs ( Common)

Artesian Discharge( Dominant)


Evaporitic ( Bathtub) Ring


EM = 35/24

Slough Bottom

NATIVE PRAIRIE: NEAR SASKATOON


EM 150/105

Bathtub Ring


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


1982-1994 -Field Studies

Dig a little Deeper- Think a little Broader

Earl Christiansen

Prof Soloninko

Paul BullockGraham Phipps


Artesian Discharge: Dominant Mechanism in Sask.

Flowing Wells Common


University of Saskatchewan : Goodale Farm

Head Above Ground1986 3.3 m 11 feet2002 2.4m 8 feet2010 4.3m 14 feet


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


Flowing and high water level wells

LAKE MANITOBA

FROM; RUTULIS, 1987 – GROUNDWATER WEST INTERLAKE


PP AQUIFER PIEZOMETRIC LEVEL

SOIL SURFACE

From “ Springs in Southern MB” Rutulis, 1985


YEAR

500m

504m


MB Flowing wells and Springs

Saline Water

Fresh Water

Artesian Brine Springs – NaClSalt first MB Industry ~ 1800


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.


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


MORAL OF THE STORY:

If you do not know where water table is

MEASURE IT


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



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


RECLAIMING SALINE SOILS1. Drainage

PLUS2. Leaching

3. If in doubt, See 1 PLUS 2


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


Tile Drainage Alone = No Solution

Southern AlbertaCirca 1989

Land had been drained so OK for busOOPs


U of S Goodale Farm

Leaching Alone

Looks Good Short Term

BUT ??


Water Table:

Soon at

Soil

Surface

1988 no rain ; no irrigation = no crop


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


Outlook : CSIDC; Terry Hogg , Laurie Tollefson

Drainage + Leaching = Long Term Solution

1986 White Crusts – Tile installed – Then lots & lots of irrigation .

Terry Hogg

1990


MANAGING SALINE LAND:

SELL IT IN THE WINTER TIME

July – Same Color


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



For severely salt affected parcels of land the only practical cropping solution is:

PLANT IT DOWN TO SALT TOLERANT GRASS



There are no quick fixes-

Nothing you are going to spray or spread

NOTHING


Alfalfa and the Water Table

Paul Brown

USDA

Montana

1970s-1980s


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


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


X= Salinized

HAMIOTA

OSBORNE CLAY- SALINE 1950s soil maps


Mapping Salinity with EM38


www.flysask.ca 2008 photo Les Henry Home Quarter

SalineTW & SLWgrass 2011

Broadcast 2010


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


THE END

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soil salinity: causes and cures - university of...

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