Crop yields as affected by soil salinity, sodicity and alkalinity

Tibor TÓTH

Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences, Budapest

EUROSOIL 2008, Vienna

Scheme of the presentation

♦ The effect of salts on plants

♦ The effect of salts on soils and the consequences for plants

♦ The nature of yield curves

♦ Comparison of yields of fertile chernozems and less fertile salt-affected soils

♦ Summary

The effect of salts on plants

normal

solution

cellwall

H2O

cyto-plasm great total

water potential

healthy turgidic plant

A) From nonsaline soil plants can easily uptake water (Seelig, 2000)

dying wilting plant

small total water potential due to salts

B) Drought or salinity decreases the total water potential, the water uptake of plants decreases (Seelig, 2000)

cellwall

saline

solution

H2O

cyto-plasm

Effect of soil salinity on yield (Tanji et al., 1990)R

elat

ive

yiel

d

Observed

Fitted

Soil salinity, EC (dS/m)

Maize

The effect of salts on soils and the consequences for plants

α ) If Naex (small valence, | β) When Ca substitutes | δ) Stabile aggregates

great hidration shell) | Na adequately the clay | are formed, good soil

>15% the clay disperse, | flocculates | structure is characteristic

the soil structure is

unfavourable

Exchangeable Na (Naex) adsorbed on the surface of colloids(Seelig, 2000)

Ca++

Na+

Ca++

Na+

α β δ

Photo: R. Langohr

α

β or δ

The solonetz soils have very dinstinct soil horizons

pH/EC2.5 dS m-1)

For a given sodicity level small salinity in infiltrating water can be a problem

Rhoades, 1977

∅

Plowland after rain (Prettenhoffer, 1969)

Deep reclamation improves infiltration of melted snow on Solonetz (Prettenhoffer, 1969)

Shallow reclamation does not solve problems with the infiltration of melted snow on Solonetz (Prettenhoffer, 1969)

Not reclaimed

Reclaimed

∅

∅

Plowland on Sodic solonchak after rain (Herke, 1950)

Plowland on Sodic solonchak (Herke, 1950)

Dispersion of soil particles can have very severe consequences (Arany, 1956)

Soil sodicity causes piping erosion

Sodicity decreases the plant available water capacity (Sumner, 1998)

∅

∅ ∅

WHEAT on Sodic solonchak (Herke, 1950)

ALFALFA on Solonetz (Prettenhoffer, 1969) RYE on Solonetz (Prettenhoffer, 1969)

As the result of elevation differences there is considerable variation ofvegetation in a Festuca pseudovina dominated Hortobágy grassland

The nature of yield curves

The plant response (yield) shows a bell-shaped curve according to Jeffrey, 1987

According to Kadar et al., 1981 the yield curve is comprising the maximum yield data

Weight

N:P

Example of (sub)systems defining fertility for less fertile soil

According to Buzas, 1987 the yield curve can be very different depending on climatic conditions and soil types

Optimal composition

Comparison of yields of fertile chernozems and less fertile salt-affected soils

Water cycle

Micro-biology

Animals Roots

Acidity buffering

Particle size

Cation

adsorption

...........

..........

More fertile soil

Example of (sub)systems defining fertility for more fertile soil

Less fertile soil

Water cycle

Roots

Acidity buffering

Particle size

Cation

adsorption

Animals

Example of (sub)systems defining fertility for less fertile soil

Value of soil property

Yield curve of more fertile soil

Yield curve of less fertile soil

Cro

p yi

eld

The slope of the regression curve belonging to the more fertile soil is smaller

The slope of the regression curve belonging to the less fertile soil is greater

~ 80.000 fields 5 years (1985-1989)

Real management data: - yields - soil nutrient tests- fertilization data

Database used

AIIRAIIR

CROP WINTER WHEAT MAIZESOIL MAINTYPES Variables in decreasing correlation strength

ALL SOIL MAIN TYPES -pH_KCl -pH_KClN=92,303 winter wheat -Soil Organic Matter -Soil Organic MatterN=58,590 maize -CaCO3 -Soil salt content

-Saturation Percent according to Arany -CaCO3

-Soil salt content-Saturation Percent according to Arany

Chernozems -Soil Organic Matter -CaCO3

N=23,237 winter wheat-Saturation Percent according to Arany -pH_KCl

N=19,523 maize -pH_KCl -Soil salt content-Soil salt content -Soil Organic Matter

-CaCO3-Saturation Percent according to Arany

Salt-affected soils -Soil Organic Matter -Soil Organic MatterN=1,737 winter wheat -pH_KCl -pH_KCl

N=350 maize-Saturation Percent according to Arany

-Saturation Percent according to Arany

-Soil salt content -CaCO3-CaCO3 -Soil salt content

Correlation between yield and soil properties

P<.01

P<.05

P>.05

curve

checked

pH (KCl)

9876543

Term

ésát

lag

q/ha

80

60

40

20

0

pH (KCl)

9876543Te

rmés

átla

g q/

ha

80

60

40

20

0

Winter wheatWinter wheat

ChChernozernozeemm SaltSalt--affected soilaffected soil

Winter wheatWinter wheat

Yield curve (q/ha) of winter wheat versus pH_KCl

Yield

Yield

pH (KCl)

9876543

Term

ésát

lag

q/ha

140

120

100

80

60

40

20

0

pH (KCl)

9876543

Term

ésát

lag

q/ha

140

120

100

80

60

40

20

0

ChChernozernozeemm SaltSalt--affected soilaffected soil

MaizeMaizeMaizeMaize

Yield curve (q/ha) of maize versus pH_KCl

Yield

Yield

Soil main types Winter wheat Maize Chernozem

N=13985 winter wheat N=12273 maize

-9.7 -5.6

Salt-affected

N=235 winter wheat N=54 maize

-13.9

-52.2

Linear regression coefficients (“B” from equationsY=A+B*X, Y=yield (q/ha) and X= pH_KCl) inside the alkaline half of the curve

The difference of regression coefficients for

-Saturation Percent : none

-Soil Organic Matter content: wheat no, maize yes.

Summary

The statistical analysis of the data showed that the theory is promising for the description of the relationship between soil properties and crop yield.

As further steps

-data filtering must be considered

-other types of soils must be compared

-other functions must be found and evaluated.

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Thank you for the attention, any questions, please?