VÁRALLYAY GyörgyResearch Institute for Soil Science and Agricultural Chemistry

Hungarian Academy of Sciences, Hungary

SALINIZATION

Introduction

Salt-affected soils (SAS) are widespread all over the world. In addition to the constraints of scarcity or too much water in these soils, the basic fertility and land use capability of these soils is directly related to a few chemical properties, such as salinity and sodicity (Szabolcs, 1991).

Definitions• Salt affected soils: formed under the influence of soluble salts• Saline soils: soils with high amount of water soluble salts• Alkaline soils: all soils having alkaline reaction• Alkali soils: soils having strongly alkaline reaction and high

amount of Na+ (Na- salts, exch. Na)• Sodic soils: Having high amount of Na2CO3 (Na2CO3)• Maritime salt affected soils: Soils formed under the direct/indirect

influence of the presence of the sea. • Continental salt affected soils: Soils formed without the

direct/indirect influence of the presence of the sea. •

The preconditions of salt accumulation 1.

• Salt resources– Local weathering– Surface water– Subsurface waters– Human activities

• Transporting agents– Wind, water

Horizontal transportation: large watershed with small accumulation area

Vertical transportation: geological strata to accumulation horizon

The preconditions of salt accumulation 2.

• Driving force for solution movement– Relief

– Hydraulic gradient

• Negative water balance• Limited drainage conditions

– Poor vertical drainage of soil profile

– Poor horizontal drainage of the area

Classification of Treitz, 1924 of the saline and alkali soils of Hungary

1. Saline soils yielding nitrates2. Soils yielding soda (temporary salt efflorescences)3. Alkali soils (there are no salt efflorescences)

A. Alkali soils on sandB. Alkali soils on clayey substances

-alkali soil of plateaus-alkali soil without CaCO3-alkali soil with CaCO3 -alkali soil in depressions

Practical classification of Hayward and Wadleigh, 1949

Soil ECe ESP pH

 Non saline <4mS/cm <15 <8.5Alkali(=sodic) <4mS/cm >15 >8.5Alkali(=sodic) saline >4mS/cm >15 <8.5Saline >4mS/cm <15 <8.5 

ECe (electrical conductivity of soil saturation extract) and the effects of salts on the yield of field crops according to the general scheme of Richards (1954).

ECe (mS/cm) class Effect on plants------------------------------------------------------------------------------------------------0-2 Salinity effects mostly negligible2-4 Yields of very sensitive crops may be restricted4-8 Yields of many crops restricted8-16 Only tolerant crops yield satisfactorily

> 16 Only a few very tolerant crops yield satisfactorily----------------------------------------------------------------------------------------------------- 

Salt balances

Total: Qt (ECSP, ECSE, SP)

Profile: Qt / fd (for layers or horizons)

Ions: Qi

t: day/week/month/year….Season

vegetation period..etc

Reason(s) factorial salt balances

Solonchaks

Solonetz soils

Salt-affected soils in Europe

16° 17° 18° 19° 20° 21° 22° 23°

22° 23°21°20°19°18°17°16°

48°

48°

47°47°

46°46°

BUDAPEST

B a l a t

o n

SALT AFFECTED SOILS IN HUNGARY

Chloride and/or sulphate solonchakSodic solonchakCalcareous meadow solonetzCalcareous meadow solonetz turning into steppe formationCalcareous solonetzic meadow soilMeadow solonetzMeadow solonetz turning into steppe formationSolonetzic meadow soilChernozem and meadow chernozem salty in deeper layersPotential salt affected soils

Compiled in RISSAC GIS Labin 1996 based on Szabolcs, Várallyay and Mélyvölgyi (1974) Hungarian Unified Map Projection System

0 50 100 150 Kilometers

Secondary salinization 1.

Secondary salinization 2.

Possibilities of salinity control• Leaching and drainage

– Preconditions• Reversible processes (Low Na+ saturation, moderate physical deterioration)• Adequate amount of good-quality water• Good vertical drainage of the soil profile (Light texture, good hydraulic

conductivity, Cl-SO4 type salinization, low alkalinity, low ESP)• Good horizontal drainage of the area• frost-free period after the vegetation season• Drain water reservior

• Prevention• Quality control of irrigation water• Stabilization of ground water table

– Prevention of rise– Lowering

• Saline seep-control