Technical University Gheorghe Asachi from Iasi [617775]

Technical University "Gheorghe Asachi" from Iasi
Faculty of Hydrotechnics, Geodesy and Environmental Engineering

Summary

Diploma Project
Techniques to improve the quality of salinated soils

Student: [anonimizat], resulting in an
extremely low fertility of the soil. This project presents a number of issues concerning the
improvement of the saturated salts.
The first chapter entitled Sources of Soluble Salts seeks to present general aspects
regarding the process of salinization along with the types of salinization, the causes and the
consequences of their occurrence, and the methods to prevent the soil degrada tion by
saturation . Thus, e asily soluble soi ls can be of primary or secondary origin. The primary
source is represented by eruptive rocks, volcanic emanations and chemical processes
occurring in natu re whilst sedimentary rocks, seas, lakes, g roundwa ter and irrigation water
constitute the secondary source. Groundwater is the main salinity fa ctor; for that matter,
water is the agent carrying easily soluble salts . The water penetrates into the earth's crust,
dissolves the soluble salts of rocks and soils, and carries th em into the aquifer layer . Under
arid or semiarid climate, with strong evapo -transpiration, there is an ascending flow of
groundwater and a gradual accumulati on of soluble sal ts in the soil.
The aquifer stratum may receive under certain conditions contributions from underground
water of greater depth. The influence of ground water on the formation and evolution of soil
is exerted depending on the climatic area , the degree of mineralization, the qualitative
composition of the soluble salts and the depth at which it is found. Under certain conditions,
groundwater can influence soil formation and evolution to such an extent that it results in the
creation of speci fic soils contained in hydro -morphic or halomorphic soil classes or soil
subtypes. The main salts that are found in soils are the Na+(Sodium) , Ca2+ (Calcium) , Mg +2
(Magnesium), K+ (Potassium) and the anions Cl2- (Chloride ), 𝑆𝑂42− (Sulfate) , 𝐻𝐶𝑂3−

(Bicarbonate), 𝐶𝑂32− (Carbonate) și 𝑁𝑂3−(Nitrate). In many soils, sodium carbonate (Na2CO3)
is often considered to be one of the most toxic salts for plants .
The accumulation of salts (especially sodium salts) is one of the main physi ological
threats to ecosystems being a direct consequence of a concentration process that oc curs after
the evaporation of water. The salt disturbs plant growth by limiting the assimilation of
nutrients and by reducing the water quality available to the plant. This affects th e metabolism
of organisms in the soil, resulting in extremely low fertility of the soil. High salinity in the
soil causes the plants to dry due to the increase in osmotic pressure and the toxic effects of
the salts. At the same time, excess sodium causes d estruction of the soil structure, wh ich, due
to lack of oxygen, can not sustain plant growth or animal breeding. Equally, the s alinization
increases the lack of permeability of the soils in depth layers , making it impossible to use the
land for cultivation.
Salinization is the accumulati on of water -soluble salts in soil. These salts include
potassium (K+), magnesium (Mg 2+), calcium (Ca 2+), chloride (Cl), sulphate (SO 42), carbonate
(CO 32), bicarbonate (HCO 3) and sodium (Na+). The a ccumulation of sodium is also called
sodiumisation. Salts dissolve and are transported together with water; w hen the wate r
evaporates, the salts remain. On the one hand, p rimary salinization involves the accumulation
of salts by natural processes due to th e high salt content of the material in soil of origin or
groundwater. On the other hand, s econdary salinization is caused by human intervention,
such as inappropriate irrigation methods, for example, with irrigation water rich in salts and /
or insufficien t drainage. Irrigations can cause secondary salinization by raising the
groundwater level , by redistributing the salt on the profile without lifting groundwater , by
irrigation with mineralized water , by damming the steppe meadows and draining the marshes
and the lakes , by flooding with mineralized water and ultimately by soil erosion . Causes of
secondary salinization of the soil on irrigated land are due to groundwater, the rise of

groundwater mineralized water levels is most often due to the irrational application of
irrigation, the use of the non-permeabilized earthing system with loss of water through
infiltratio n that can exceed 50% o f the total flow, by choosing an inappropriate watering
method under hydro -geologic al and pedological conditions, by applying large watering rules.
Prevention of soil degradation by salinization is achieved through t he following groups of
measures: organi zational and household measures, measures to regulariz e the water balance
in the soil, agro-technical measures.
The second chapter entitled The c haracterisation of Saline Soils , includes the
classification of salts, and the pedogenetical horizons of the salin e alkaline soils, along with
clues to characterize the saline and alkali ne soils. These indexes are hydro -geological
indexes, pedological indexes, ameliorative and agricultural indexes. The improvement of
saline and alkaline soils, as well as of salinized and alkali zed soils, i s generally a difficult
problem to solve since it requires expensive work , it is also necessary to know the type of
salinity and its characteristics in order to be able to choose the most appropriate improvement
measure , following the lifting of their.
Saline a nd alkaline soils exhibit (an excess over the salinity toleran ce limit of crop plants)
either only solu ble salts (saline soils) or just the exchangeable sodium in the adsorbent
complex (alkaline soils) or both fertility soluble soils, a s well as exchangeable sodium
(alkaline salts). The term alkaline soil only refers to the presence of excess exchangeable
sodium compared to the alkaline soil, which corresponds to alkaline reaction soils with a pH
greater than 7.2. Alkaline soils usually have an alkaline reaction, and when they contain soda,
they are excessively alkaline . The pedogenetic al horizons of saline and alkali ne soils are:
salic, salinized , gleyed , nitric, alkalized, eluvial, albic, calcic, gypsum and sulphuric horizon.
For characterization of saline soils we take into account the pedological, hydro -geological
indices, the needs in the improvement technologies, drainage, finishing, washing etc. The

important proprieties are nature of salinization and her intensity , profil e texture, the unit of
relief in which the soil is located, t he depth of the water and its degree of mineralization.
Another soil characterizati on criterion is based on indexes , and here are the hydro -geological,
pedological, ame liorative and agricultural index es.
Chapter III is focusing on Improving the Sa line Drained Soils by Applying a Comp lex of
Improvement Technologies by appropriate means. Previously I sought to present the
improvement of the saline and alkali ne soils, the influence of capital levering, the influence
of the complex of ameliorative technologies on drained soils and the land preparation for
washing. In our country , the improvement of saline soils is achieved during the improvement
period, when the capital improvement technologies are applied, but it continues during the
intensive exploitation period. Stabi lization of the salinity regime along with the improvement
of the chemical composition of the salts is done through drainage by applying the main
washings that exclude the possibilities of reshaping.
The main technological aspects of levelling and landscaping for washing are: determining
the period of execution of the capi tal levelling ; execution phases; t he assembly of capital
levelling works with other complementary works and various aspects regarding the
landscaping for washing. On soils affected by saliniz ation, the process of drainage is less
intensive, has a prophylactic, ameliorative character. The drainage facilities have particul ar
tasks during the application of capital and / or prophylactic ameliorative technologies, but
also during the vegetation period of agricultural crops under intensive exploitation, the
practice of a high -yield farming system. Drainage arran gements have a multiple role: they
stabilize agricu ltural production, reduce both the harmful influence of groundwater, salts and
pesticides on human health contributing to the protection of the environment. There are
several types of drainage: drainage through closed pi pes, open channel drainage, vertical
drainage and combined drainage.

The determination of the dose of amendments is established according to the pedological,
technological parameters (washing standard, washing water quality, depth of work,
loosening, moult ing drains, degree of homogenization of the s oil amendment) and
ameliorative. The w ashing of the soluble salts in the soil is a complex, m ultiphase and not
mechanical process which can be explained on the basis of water balance and salts, but in
particular by applying the physicochemical laws of hydrodynamics. Washing is the basic
work in improving saline soils with poor amelioration conditions. During first wash, soluble
salts are discharged. Sulphates and sodium carbonates remain in the soil from sodium and
calcium chloride, magnesium sulphate. Ion exchange reactions occur between the salts in the
soil solution, the colloidal complex, in which sodium and magnesium are adsorbed or
removed.
The soil indicators are: profile texture, hydraulic conductivity of the soil and subsoil, the
quantity and distribution of soluble salts, the composition of the exchangeable cations, the
hydro -physical ones (hygroscopicity coefficient, wicking coef ficient, water field capacity,
active hum idity range, infiltration rate a nd aggregate capacity), aggregate state, soil and soil
solubility capacity of soluble salts, soil profile thickness to be desalted. Hydro -geological
indices are also quoted: depth, degree of mineralization and ionic chemical compositio n of
phreatic waters; leakage, t he actual depth of the critical level (which represents the average
depth of groundwater in a certain season of accumulation of soluble salts).The technological
indices a re: the process of drainage and its functionality, the va lue (size) of the drainage
mode, t he functionality and intensity of the mole drains, deep loaves and debris, method and
time of washing.
• Methods of washing the excess of soluble salts in the soil
Various types of soils require different washings such as capital washing, flood washing,
intermittent washing, furrow washing, lateral washing, apertures and soil irrigation. All of

these methods are useful for desalinating soils that meet certain conditi ons. In many cases,
the failure of washing is due to soil properties, high salinity, and very low water permeability.
In this case, in order to increase the washing efficiency, some mechanical measures, prior to
washing, are taken to improve the hydro -physical properties of the soils (leakage, moult
drains).
Chapter IV, The Improvement of Saline Soils by A gro-podo -ameliorative technologies
deals with the main issues of improving the saline drained or undraine d soils by agro -pedo –
ameliorative technol ogies and meadow s. The main problems of soil salt improvement on a
draining or unnatural background are addressed through agro -pedological technologies and
meadows. These technologies can be applied on the territories with satisfactory internal
drainage, rep resented by molic -cambic soil s with small, middle, large, vertically -gleic
columns, etc., with phreatic waters situated in autumn to depths above 1, 40 -1,50 m and
secured.
• The targets of improvement of mole drains
Mouth drains provide the following important goals: disturbing and breaking the alkaline
horizons, improving the penetration of the water into the soil, increasing the duration of its
storage on the profile , improving water permeability, water storage conditions, incr easing the
duration of maintenance in the soil profile.
• Pedological indices for setting the mole drainage technology
The technology is based on the morphology of the soil profile (texture, distribution of soluble
salts, exchangeable cations on the profile, water and salt yield capacity), soil desalination
stage during the soil improvement period . Mouth drains consist of the execution in the soil at
the desired depth (usually between 30 -70 cm) of continuous cylindrical galleries in which
saline, wash water or stagnant water is collected and discharged by leakage.

Experiments have shown that drainage executed on a double -deck system provide good
results : the first floor at 35 -50 cm (depending on the morphology of the soil profile) and the
dista nce between rows of 1.60 m and the second floor at the depth of 60 -70 cm all at a
distance of 1.60 m (each row of drains is located between the first floor strings). The main
agro-pedo -ameliorative technologies for soil salt improvement are land mode lling, operating
level ling, petitioning, gypsum finishing, sanding and intake of imp roving materials, loosening
and scaling, partial mopping, mole drainage, ditch d rainage , re-cultivation, a meliorative
fertilization, the cultivation of protective and ameliorative crops. It is emphasized that in the
most frequent situations for enhancing the process of improvement and valorisation of soils,
the mentioned technologies are applied in complex, th e dimensioning of the parameters being
made after the pedological and ameliorative soil conditions.
In the last chapter called Monitoring the Evolution of Saline Soils after I mprovement I
introduced the agricultural techniques used on salty soils, and the case study had as object
establishing the optimum parameters of the horizontal drainage to achieve regulation of the
water and saline regime of alluvial clay and saline soils in the area. The improvement of the
salinized land, optimizing the water regime, is a basic component of achieving higher and
stable production. For this purpose, the analysed area can be divided into hydro -ameliorative
units. The finishing w orks are: embankment, drainage and sprinkling irr igation. Drainage
works are designed to ensure the drainage of excess moisture from precipitation and
groundwater, water evacuation from soil salts, improved soil aeration, increased biological
activity to improve soil physical and chemical properties. Irrigation works have the role to
raise the agricultural potential of the enclosures and to alleviate the desolate soils by washing
the salts in the soil layer in which the plant root system develops (watering to fill the moisture
and wash deficiency). Water distribution is carried out with a pipeline network under
pressure, watering is applied by sprinkling. In order to avoid soil degradation under the

influence of irrigation, especially in areas lacking underground drainage, rigorous control of
their evoluti on is necessary.
• Agricultural techniques used on salty soils
Gipsy admixture is a complex agro -pedo -ameliorative work. It consists not only in spreading
and mixing in the soil mass of different doses of materials that are used as amendments to
reduce the e xchangeable sodium content. Deep hatching includes all the work aimed at
increasing or increasing the gap, the soil horizons underlying the arable layer, the works that
do not involve mixing, the overturning or reversal of soil specific horizons.
Soil work systems are complex and differ widely from one area to another, primarily
depending on pedo -climatic factors and can only be properly solved and appreciated during a
cropping. Drainage and irrigation greatly influence soil work systems. Channel networ ks
condition t he size and the outline of the soil along with the use of complex soil cultivation
aggregates. The ridge is the main work, its depth having two important aspects: agrotechnical
and energetic. Ameliorative fertilization is an agro -pedo amelior ative work done to restore,
maintain, and increase the production capacity of soils that have suffered intense, natural
anthropic processes, fertility degradation, as well as increasing the production potential of
poorly developed soils.
The investigations that took place in the experimental field Osoi – Moreni were
approximately at the centre of this area and aimed at establishing the optimal parame ters of
the horizontal drainage f or the regulation of the hydric and salt regime of the clay soil and
salinized alluvial soils in the area. Also, the effects of the work of the hydro -ameliorative
association with the agro -pedo-ameliorative ones were pursued in order to establish the most
efficient amelioration technologies. The Osoi -Moreni exp erimental field is located in the
Sculeni -Gorban hydro -ameliorative unit, which occupies an area of 35043 ha. It is
characterized by the presence on the surface of a 4 -13 m thick and permeable complex

consisting of sloppy clay and dust clay. Below is a per meable complex consisting of sands
and gravel in a thickness of 2 -13 m. The piezometric line of the underground layer is at a
depth of 1 -3 m. The groundwater is mineralized, the salts from the washing of the Sarmatian
rocks existing in the Jijia river basi n and which have eroded in the eroded areas. The degree
of saliniz ation depends on the depth of the groundwater and its degree of mineralization.
Groundwater has bicarbonate sulfato -sodic type of mineralization.
• Hydro physical indices of the soil improving their modifications through drainage
works and agro -pedo -ameliorative measures.
In the pedological studies, the main problems of the soil salinity to be highlighted are the
salty sources, the mig ration process, the migration and accumulation on soluble salts, location
of salinity in ground units , on the thickness of the soil profile, of the ground – parental
material – groundwater system, the prognosis of the salinity evolution of that territory. The
objective of the case stud y is to establish the optimum parameters of the horizontal drainage
(the distance between drains, posing depth, the material from which a drain is made and the
filter provided) to achieve the adjustment of the water and saline regime of the alluvial clay
and saline soils in the area . The effects of the association of hydro -ameliorative works with
agro-pedo -ameliorative works were surveyed in order to establish improvement technologies
with maximum efficiency . Initiating measures were imposed in order to improve the soils,
consisting of capital washes and then improvements with prophylactic washes aiming to
prevent salinization.
• Results obtained in the experimental field Osoi – Prut regardi ng the improvement of
saline soils
Following the agro -pedo -ameliora tive drainage, drainage and irrigation works, conditions
have been created for the improvement of saline soils. In order to efficiently improve the fine
texture of the soil, it is necessary to apply a set of measures consisting of: washing, chemical

finishing, loosening accompanied by superior agrotechnics. The salinity of the soil in the
experimental field is determined mainly by the level of the groundwater, regulated by the
drainage, respectively by their depth and their degree of mineralization. By applying
irrigatio n, the salinity regime will depend in the future on the irrigation regime.
• Soil improvement measures consisting of capital washes continued after
improvement with prophylactic washes to prevent salinization .
Experimental results perform ed in our country as well as results from other countries show
that salinity reduction by intermittent washes are indicated using the sprinkling irrigation
method. These processes of watering can take place either outside the growing season or
during the vegetation period. The irrigation has as a direct result an increase in compaction
and respectively in the app arent density of the soil, whilst the porosity and the rate o f
infiltration of water decrease. By level ling, there is a breakage and shredding of alkaline
horizons, an increase in permeability and water storage capacity. This, together with
drainage, prevents water stagnation and facilitates lowering groundwater levels, improving
soil oxidation processes, forming the structure and changing permeabil ity.
Irrigations cause changes in the cation exchange complex, nitrates from chemical
fertilizers are deeply trained, phosphorus, potassium and other micro and macro -elements are
solubilised . Irrigation can also cause secondary salinization of the soil. Th e effect of
irrigation and drainage can be manifested by either lowering the pH value – due to the
oxidation of sulphides and sulphuric acid formation, or by increasing the pH value by
washing the soluble solutions and losing their buffering effect. Under irrigation conditions an
accelerated mineralization of organic matter occurs, especially in the early years,
accompanied by a decrease in humus content.
The soil degradation, which is an essential factor of the environment, is based both on
the action of c hemical, physical, biological and radioactive factors and the human activities,

so this can be monitored using the device for determining the soil conductivity Ec-probe /Ec-
samples. The device measuring the Earth resistivity is applied for determining the electrical
conductivity of the soil to a depth of cm 110.The depth of the operation allows measuring the
salt content in the rooted soils, in the furrows, in the separate layers of t he soil.
The hy dro-amelioration technique, which controls the regulation of the soil water
regime, irrigation and drainage, exerts large, often radical, influences on soils, by changing
the hydrosaline balance, the water -air ratio, the ac tivity of microorg anisms, etc. The irrigation
represented, represents and will represent the decisive path through which the agricultural
production will be intensified, will increase the surfaces to be taken in the culture, ensuring
the stability and the safety of the fund amental basis of human life – agriculture. Irrigations
primarily shelter land affected by undesirable seismic phenomena, increasing the premises of
ensuring, at least in poor water years, the country's food base. Therefore, from the brief
review, it can be concluded that irrigated and drained agriculture is a safe and effective mercy
in raising the living standard of the population around the world. However, the benefits from
the existence and development of irrigation and drainage can be overshadowed by a series of
negative effects, which arise as a result of the faulty practice of these works. Their knowledge
will improve the practice of design, execution and exploitation, in order to obtain maximum
efficiency, on the general background of preserv ing natur al ecological balance.

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