There are original saline soils on greater areas of Azerbaijan, so-called soils with dealluvial form of salinization, located in foothill zone of republic in conditions of deep lying of subsoil waters. An origin and features of its salinization are found out absolutely insufficiently. Meanwhile, now the industrial organizations have already partially started development of these soils that is connected with greater difficulties in connection with their small level of scrutiny. Considering it, the Institute of Soil science and Agrochemistry of the Academy of Sciences of Azerbaijan SSR has considered necessary to organize special research with the purpose of studying of specificity of these soils, as new object of development, and questions of its land improvement.
We have chosen areas of southeast Shirvan, a northwest part of the Karabakh steppe and a northwest part of Near-Caspian lowland as objects of field researches.
Works on field researches included into the program:
1) Founding stationary areas and studying of physical and chemical properties of soils of these areas;
2) Carrying out of stationary supervision on water-salt dynamics of soils on 12 areas;
3) Carrying out of washings on micro allotments.
The characteristic of soils of southeast Shirvan on an example of Kyurovdag area and results of washing of soils in Siyazan and Sumgayit areas is provided in the given article.
Mechanical structure of soils
The mechanical structure of soils of described area changes depending on a bias of district, i.e. on a structure dealluvial slope. In the scheme the mechanical structure of soils becomes rougher in a direction towards mountains. The contents of physical clay in soils of top part of foothill zone are less than in median and then daisy parts of dealluvial slope. In the top part of area the soils are light and mid loamy. The contents of physical clay in them average 40-45 %.
In medina part of area the mechanical structure is made heavier, the ground has hard loamy and light loamy mechanical structure. The contents of physical clay make 50-70 %.
Soils of daisy parts of area differ completely with hard loamy mechanical structure. As a rule, the contents of physical clay here and on separate horizons, and on a profile make over 80 %.
Salinity of soils
Salinity of soils on various platforms is characterized on depth in a different degree. In the top part of foothill zones soil also have powerful (60-80 sm) freshened top and saline bottom layer. In a median part of foothill zones capacity of the freshened top layer decreases a little, being hesitated within the limits of 35-50 sm, and the contents of readily soluble salts here rather is more (0,5-0,8 % of the dense residue) than in the top part of researched area where the contents of salts in the freshened layer makes 0,1-0,4 %.
In the daisy parts of foothill zones of researched area salinity sharply increases, and the top freshened horizon here almost is absent. Soils of this part of area have a saline salt structure. On morphological properties they are similar to takyrs.
Characteristic feature of soils in daisy parts of area is still that the maximum of the contents of salts (approx more than 3 %) in them is observed in a median part of a soil structure.
The top horizons of all described soils are characterized by rather high contents of bio-carbonates (0,07-0,1 %).
In a soil structure almost in all cases salts of NаС1 and Nа2SО4 prevail. In rare cases presence of СаSО4 is marked. Prevailing with anions are С1, and then SО4, with cations of Nа.
Salinization of soils in researched area in our opinion occurs by double ways: under influence of dealluvial deposits separately and in a combination with influence of capillary edging of subsoil waters.
Alkalinity of soils
All soil differences of the researched area freshened from readily soluble salts from a surface, and in a smaller measure saline soils also carry in a different degree of feature of alkalinity, for example, in soils of a median part of dealluvial slope the absorbed sodium makes 15-18 % from the sum of the absorbed bases.
Though the high contents of sodium is marked in the bottom horizons of researched soils, it does not show the harmful influence on physical properties of soil as many readily soluble salts contain in a soil solution of the bottom layers.
Water-salt dynamics of soils
The course of water-salt of dynamics of soils in researched area changes depending on a bias and height of district. Thus sharp change in moisture content and salts in ground on a structure is marked, too.
On foot of dealluvial slopes the soils are characterized with impermacide humidifying, i.e top layers of soils under influence of atmospheric precipitation and dealluvial streams periodically appear in rather more humidified condition and differ with some dynamism in moisture content.
Median and deep layers of soils almost all season appear more dried up (within the limits of 5-10 %) that shows an absence of influence of capillary edging of subsoil waters and presence of the condensed horizon in median layers of soils, interfering infiltration of atmospheric precipitation and dealluvial streams. Besides magnificently developed here halophytic plants, having long root system, regularly transpire moisture from median and deep layers.
Between dynamics of humidity and dynamics of salinization of soils inverse relationship is papered, i.e. horizons confined for rather high humidifying, have lowered salinization (0,10-0,15 %), and in the bottom layers where low constant humidity is observed, are marked with high salinity of soils (1,0-1,6 %).
Soils of a median part of dealluvial slopes are characterized in the top horizons by greater dynamism of a water regime. Here the capacity of a dynamical top layer almost is twice more, than in the top part of dealluvial slopes that shows apparently, rather more even surface. It creates favorable conditions for deep infiltration as atmospheric precipitation, and dealluvial streams.
Below a dynamical top layer humidity of a soil structure changes a little, being fluctuated within the limits of 15-20 %.
Similar dynamism is observed in salinization regime.
The soils located in daisy zone of dealluvial slopes differ from located on rather high marks of dealluvial slopes that dynamism of water - salt regime on all structure of soils here is marked.
In median 100-160-cms layer of soils part of area during almost all supervision the maximum of the contents of salts is marked, approx. 3 % and more, that is characteristic for these soils.
Thus, soils of researched area on the basic properties are divided on three groups:
I. Soils of the top zone of dealluvial slopes with light and median-loamy mechanical property, solonzetic salt structure, big alkalinity and imperacide (not washing) water regime.
II. Soils of an average zone of dealluvial slopes with hard loamy and light loamy mechanical structure, a saline salt structure, high alkalinity and a washing water regime.
III. Soils of daisy zones of dealluvial slopes with median and hard loamy mechanical structure, a typical salt structure of saline soil, significant alkalinity, appreciable surface and high soil humidifying.