Ecological-Geochemical Assessment of Soil Salinization and Humus Degradation in the Irrigated Lands of Kashkadarya Province, Uzbekistan

Author: Oʻktamova Sabrina Mahmud qizi

1st-year Student of Ecology, Faculty of Geography and Agronomy, Karshi State University, Uzbekistan

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Abstract

Anthropogenic land degradation in the arid zones of Central Asia poses a severe threat to agricultural security. This study presents a comprehensive ecological-geochemical assessment of irrigated soils in the Karshi Steppe of the Kashkadarya Province, focusing on Kasbi and Nishan districts. Soil samples collected from the 0–20 cm and 20–40 cm depths were systematically analyzed for pH, electrical conductivity (EC_1:5), dry residue (TDR), individual toxic ions (Cl^-, SO_4^2-), and soil organic matter (SOM/Humus). The geochemical analysis revealed a predominant sulfate-chloride type of secondary salinization, with dry residue values exceeding $1.1\%$ in heavily impacted zones of the Kasbi district. Concurrently, a critical decline in soil organic matter was observed, with average humus levels dropping to $0.65\%–0.88\%$. This paper establishes the direct correlation between high saline groundwater tables and topsoil degradation, proposing integrated ecological mitigation measures such as gypsum application, biological drainage, and conservation agriculture to halt further desertification in southern Uzbekistan.

Keywords: Karshi Steppe, Kashkadarya, Soil Salinization, Sulfate-Chloride Chemistry, Humus Depletion, Arid Geochemistry.

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1. Introduction

The transformation of the Karshi Steppe in the southern part of Uzbekistan during the 1970s via the construction of the Karshi Cascade of Canals stands as one of the largest hydrological engineering feats in Central Asia. It brought over a million hectares of virgin grey-brown (bo’z-qo’ng’ir) and desert soils under intensive irrigation, primarily for cotton and wheat monoculture. However, this massive anthropogenic intervention lacked sufficient closed horizontal and vertical drainage networks, leading to a long-term ecological imbalance (Gafurova et al., 2020).

Under the influence of a sharply continental, arid climate—where potential evapotranspiration exceeds precipitation by almost tenfold—the water-salt balance of the region’s soils has shifted dramatically. The saline groundwater table has risen from a depth of 10–15 meters to a critical level of 1.5–2.0 meters from the surface (Kuziev & Sektimenko, 2009).Capillary forces continuously pull this brackish water upward, depositing high concentrations of toxic sodium chloride and magnesium sulfate in the root zone upon evaporation.

In addition to salinization, the ecological status of these soils is highly threatened by organic carbon depletion. Humus (soil organic matter) is the core indicator of soil biological activity and physical structure. Intensive tillage, burning of crop residues, and lack of organic manure application have accelerated the mineralization of organic carbon, leading to a structural collapse of the soil. This study aims to provide a precise geochemical and ecological evaluation of these dual degradation processes in the Kasbi and Nishan districts of Kashkadarya.

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2. Materials and Methods

2.1. Study Area and Environmental Settings

The research focused on the irrigated agricultural zones of Kasbi district (characterized by clayey-loam meadow alluvial soils) and Nishan district (characterized by sandy-loam grey-brown soils). The regional climate is characterized by an average annual temperature of 16.2°C and an annual rainfall of only 180–210 mm, concentrated mainly between November and April.

2.2. Sampling and Analytical Geochemical Methods

A total of 20 representative soil profiles were dug, and composite samples were collected at depths of 0–20 cm (rhizosphere/plow layer) and 20–40 cm (subsoil). The samples were air-dried, crushed, and passed through a 2-mm sieve. 

• Water Extract Analysis (1:5 ratio): Used to determine total soluble salts (Dry Residue), chloride anions (Cl^-) via Argentometric titration, and sulfate anions (SO_4^2-) via precipitation with barium chloride.

• Electrical Conductivity (EC_1:5): Measured using a calibrated digital EC meter.

• Soil Organic Matter (SOM): Determined using the Tyurin method (wet combustion with K_2Cr_2O_7 and H_2SO_4), followed by titration with Mohr’s salt.

• Soil pH: Evaluated in a 1:2.5 soil-water suspension using a glass electrode pH-meter.

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3. Results and Discussion

The laboratory geochemical data presents a clear picture of severe soil degradation and secondary salinization profiles in the studied districts (Table 1).

Table 1: Geochemical and Chemical Profile of Irrigated Soils in Kashkadarya Province

3.1. Chemical Typing of Salinization

The ratio of anions (Cl^- / SO_4^2-) is the primary geochemical index used to classify the type of soil salinity. 

• In the Kasbi district, the ratio is approximately $0.54$, which firmly categorizes the soils under the Sulfate-Chloride type of salinization. This indicates a highly toxic environment, as high chlorine ions inhibit the enzymatic activity of the soil and restrict the uptake of essential nutrients like nitrogen and phosphorus by crops.

• In the Nishan district, the salinity is slightly lower but still harmful, displaying a Chloride-Sulfate chemistry with a dry residue of $0.58\%$ in the topsoil.

3.2. Humus Depletion and Ecological Imbalance

The soil organic matter (Humus) content in the plow layer (0–20 cm) of both districts is dangerously low, ranging between $0.68\%$ and $0.85\%$. Historically, the native soils of the Karshi Steppe maintained a humus baseline of $1.5\%–1.8\%$. 

This dramatic decline ($>50\%$ loss) is a direct consequence of:

1. Intensive tillage: Conventional deep plowing accelerates the exposure of organic compounds to microbial decomposition, leading to rapid carbon mineralization into CO_2.

2. Absence of Crop Rotation: The continuous rotation of cotton and wheat without alfalfa (bedapoya) or cover crops has depleted the natural nitrogen-carbon cycle.

3. High Salinity Stress: High salt levels restrict the growth of soil microbes, lowering the overall microbial biomass carbon and preventing the natural synthesis of humic substances.

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4. Advanced Ecological Mitigation Strategies

To restore the ecological health of Kashkadarya’s soils, a multi-tiered ecological approach must be implemented:

1. Chemical Amelioration (Gypsum Application): Since these soils exhibit high pH ($>8.3$) and sodium accumulation, applying phosphogypsum (CaSO_4 · 2H_2O) is necessary to replace toxic sodium ions (Na^+) on the soil clay exchange complex with calcium (Ca^2+), thereby improving soil structure and water permeability.

2. Phytoremediation with Halophytes: Cultivating deep-rooting halophytes like Glycyrrhiza glabra (Licorice) and Atriplex nitens helps lower the saline water table through biodrainage and removes toxic salts from the upper horizons.

3. Humus Restoration via Conservation Tillage: Transitioning to Minimum Tillage or No-Till systems, coupled with applying biochar and organic composts (15–20 tons/ha), will sequester carbon and rebuild the degraded humus layer.

5. Conclusion

The agricultural lands of Kasbi and Nishan districts in the Kashkadarya Province are undergoing profound ecological stress. The dual pressure of sulfate-chloride secondary salinization and extreme humus depletion has crippled the soil’s natural productivity. Correcting this ecological trajectory requires an immediate transition from intensive conventional farming to modern, eco-friendly conservation agriculture and biological 

References 

1. **Gafurova, L. A., & Nabiyeva, G. M.(2020). Degradation of irrigated soils under the influence of anthropogenic factors in the southern regions of Uzbekistan. Journal of Soil Science and Agrochemistry, 74(3), 145-154.

2. Kuziev, R. K., & Sektimenko, V. E. (2009). The Soils of Uzbekistan: Genesis, Classification, and Ecological Status. Tashkent: Fan Publishing House, 256 p.

3. Pankova, E. I., & Konyushkova, M. V. (2013). Assessment of soil salinization in the irrigated lands of Central Asia using remote sensing and ground truth data. Arid Ecosystems, 3(4), 212-221.

4. Shirokova, Y. I., & Morozov, A. N. (2006). Salinization of irrigated lands in Uzbekistan and ways to improve the state of soils. Irrigation and Drainage, 55(s1), 53-62.

5. Ibrakhimov, M., Park, S. J., & Vlek, P. L. G. (2007). Temporal dynamics of groundwater table and salinity in the lower reaches of the Amu Darya River. Agricultural Water Management, 92(3), 115-126

Oʻktamova Sabrina Mahmud qizi is a prominent and highly intellectual young representative of modern Uzbek youth, distinguished by her thirst for knowledge, social activism, and ambitious goals for the future.

Born on March 24, 2007, in Karshi city, Kashkadarya region, into an intellectual family, Sabrina graduated from school with excellent grades. She gained admission to Karshi State University (QarDU) on a state grant, where she is currently pursuing her bachelor’s degree in Ecology.

Despite her young age, Sabrina’s ability to fully capitalize on opportunities and achieve remarkable success is greatly supported by her parents, Islomov Mahmud and Geldiyeva Shahnoza. Her elder sister, Jasmina Makhmudovna, has been a key mentor and a significant source of inspiration in fostering Sabrina’s profound passion for knowledge and excellence.

Sabrina’s current achievements include:

• An active Eco-Volunteer and Social Volunteer.

• Regional winner of the Vociep project.

• Member of the “Children and Youth Support Movement” and a recipient of its special badge.

• An active member of the People’s Democratic Party.

• Recipient of over a hundred certificates from various educational and extracurricular programs.

• Participant in several international forums.

• An active participant and international certificate holder in the recent International Eco-Zakovat competition, recognized as a talented and active student and leader.

• An active member of the Kashkadarya “Golden Wing” Organization and the Youth Golden Wing initiative.

• Recipient of multiple Machine Learning (ML) grants.

Sabrina embodies a dynamic spirit, combining academic excellence with a strong commitment to social and environmental causes, making her a highly promising future leader and expert in the field of ecology.

The Voice Unseen

A heart full of passion,

And eyes full of dreams.

Her voice so warm, so sweet,

Flowed gently like a stream.

She sang her best,

No soul could stand against.

They heard a voice,

Yet judged her face.

“Talent without beauty,

Has no place to begin.

Just look at every star,

They sing, and beauty lets them in.”

She left her hope,

With tears unseen.

Talent lost to beauty,

Like countless broken dreams.

……………………..

Poem by: Md. Naeem Aziz

Poem Note: The Voice Unseen tells the story of a gifted girl whose extraordinary voice is ignored because of her appearance. Despite her remarkable talent, she is rejected by judges who value beauty over ability. The poem exposes the unfair standards that silence countless gifted people. It reflects the pain of broken dreams and overlooked potential. Ultimately, it reminds us that true talent should never be measured by outward beauty.

(This poem reveals society’s Dark Side Of Valuing Beauty Over Talent.)

Poet Bio: Md. Naeem Aziz is a Bangladeshi poet, author, engineer, and photographer, born on 10 December 1998. He is best known for his poetry and photography. His literary works have gained international recognition, and one of his poems has been included in an English literature textbook in Italy. Through his writing, he explores themes of humanity, society, history, and emotion. (nknaeem14@gmail.com)

Location: Dhaka, Bangladesh

APPARITIONS 

 Jernail S. Anand 

Man’s limitations are his 

Greatest strength 

And they make our lives 

Beautiful and worthy 

Knowing more than we should 

And doing more than humanly possible 

Is entering the weird zone

Of the supernatural 

AI which enhances our powers 

And disregards all controls 

Is a dangerous equipment 

For mankind 

I don’t want to know more than 

Is needed 

Nor hear more than I should, 

I love my limits 

I don’t want to leave 

The human realms and enter 

The super powered zones

Of Artificial Wisdom

Outgrowing out selves 

Is acquiring demonic powers 

Can we drop our humanity

And become apparitions?

Clandestine Journey

I am the man with the biggest mouth in Hebei Province,

Choosing only the words that favor me
from those that drift about the world.

People fly into Lintong—
I do not know them, yet they act as though they know me.
Wherever the boredom of life touches down,
the lines grow long, and the borders of the world contract.
I am a persuasive traveler.
Truth is, the days I have not faced the mirror
pile up damp and dim within me.

I have long dwelled in the darkness
where lions made their camp—
but this, still, is my secret city.

Unaware that arrows were tailing me,
I made my rounds until illness struck me down in Sagugung.
A man slandered by their lips,
mocked, I left Qin again and again.

Now I can understand the Jeolla dialect
that once cursed me for building a grand tomb.
No one has seen my face
since death came upon me suddenly, like burning paper—
a quiet death, making all worldly splendor pale.

A tomb is a warm place
for the one who looks toward the far corner
rather than a neighbor’s plot.
A woman—an aide to the angels—
touches the sleepers in their burial hollows
whispering with a few lingering spirits in Xi’an.

The world you live in is one of deceit and deception.
Pass by coldly, like rain.
If you glance about at unseen followers,
the tail that notices your faltering step—
then comes the jolt, and what follows, no one can tell.

The soldiers of the Terracotta Army
still roll their sorrowful eyes.

I am the man with the longest neck in Hebei Province—
Qin Shi Huang, who sleeps in short bursts like a giraffe.

Profile

Poet Yeon Myeong-ji began her literary career in 2013 with the poetry collection 『Gashibi』, published in the Minerva Poetry Series.

Her published works include the poetry collections 『Sitting Like an Apple』 and 『Where would the House of the  Sorry’ be? 』 the e-poetry collection 『Seventeen Marco Polos,』 and the travel essay 『Step by Step, Walking the Camino.』

She has received the Tolstoy Literary Award, the Homi Literary Award, the Cheongsong Gaekju Literary Award, and the Aviation Literary Award. In 2025, she was awarded the Bronze Prize in Poetry at the Literature Asia Awards.

Her poems have been translated and published in local languages in India, Pakistan, Kosovo, Italy, Egypt, the United States, and Belgium, UK, Germany.

WRITING IN THE SAND

Some loves 

It’s like writing in the sand

Evanesces

Disappears

Some loves 

It’s like night

Darkness 

Burn out

Then

Its name is

Love is not 

Just fate.

Türkan Ergör, Sociologist, Philosopher, Writer, Poet, Art Photography Model. Türkan Ergör was born 19 March 1975 in the city of Çanakkale, Türkiye. She was selected International “Best Poet 2020”. She was selected International “Best Poet, Author/Writer 2021”. She was selected International “Best Poet, Writer/Author 2022”. She was awarded the FIRST PRIZE FOR THE OUTSTANDING AUTHOR IN 2022. She was awarded the 2023 “Zheng Nian Cup” “National Literary First Prize” by Beijing Awareness Literature Museum. She was awarded the “Certificate of Honor and Appreciation” and “Crimean Badge” by İSMAİL GASPRİNSKİY SCIENCE AND ART ACADEMY. She was awarded the “14k Gold Pen Award” by ESCRITORES SIN FRONTERAS ORGANIZACIÓN INTERNACIONAL.

STUDYING ABROAD  – A DOOR OPENED TOWARD DREAMS 

«The future begins today», and this wisdom carries a deep meaning. The goals a person sets today determine the results they achieve tomorrow. I am also one of the young people who have set a great goal for their future. I have recently successfully completed the 9^th grade at School No.16 “ JASORAT” in Kasbi district, Kashkadarya region, and I am stepping forward into the 10^th grade with confidence. During this important period of my life, I have started thinking more seriously about my future and the path I want to follow. I believe that every person has a moment or an encounter that changes the way they see life. I experienced such a moment as well.

A foreign teacher who came to our school to teach us became one of the main reasons why my interest in studying abroad grew stronger. This teacher not only shared knowledge about their subject but also introduced us to their country’s education system, culture, traditions and way of thinking. Through their lessons, I realized that the true purpose of education is not only to receive good grades, but also to learn how to think independently, explore new ideas, create innovations, and become connected with the world. From that moment, studying abroad became one of my greatest dreams and goals.

The people who have given me the greatest support on this journey are my parents. When I shared my dream of studying abroad with them, they welcomed my idea, believe in me, and encouraged me to work hard. I deeply understand that the trust and support of parents are among the greatest sources of strength for a child. Their prayers and encouragement motivate me to move forward toward my goals every day.

Today, studying abroad is not only an opportunity for the children of wealthy families, as some people may think. If a person has a thirst for knowledge, dedication, and determination, may universities around the world can open their doors to them. Various scholarships, grants and international education programs are helping thousands of young people achieve their dreams. However, to take advantage of these opportunities, it is necessary to improve English exams such as IELTS and SAT, study school subjects deeply, and continuously work on personal development.

There are many advantages to studying abroad. First of all, students have the opportunity to study with modern laboratories, experienced professors, and advanced educational methods. They can combine theoretical knowledge with practical experience. By studying together with students from different countries, they can discover new cultures, lifestyles, and prespectives. This experience broadens their worldview, helps them enhance foreign language skills, and allows them to build international friendships.

Another important benefit of studying abroad is that it prepares a person for independent life. Managing time effectively, taking responsibility, solves issues freely, and adapting to different environments are valuable qualities that develop through such experiences. These skills become a strong foundation for future success.

Many people think that entering a foreign university is extremely difficult. However, the hardest step is often the first one – starting!. Reading one page of a book today, learning a new English word, or solving one mathematical problems may seem like a small achievement. But these small steps can lead you towards the world’s most prestigious universities in the future. Great achievements always begin with small actions.

I am also following this path today. I am sorting out improving my English skills and preparing to achieve international certificates such as IELTS, SAT, and other qualifications. I know that many challenges are waiting ahead, but I believe that every challenges will bring me closer to my goal. I am not working only for myself, but also to justify my family’s trust, appreciate the efforts of my teachers, and contribute to the development of my homeland in the future.

Dear friends and fellow students! If you also dream of studying abroad, do not postpone your dreams. Start working from TODAY.  Learn languages, read books, participate in competitions, and never stop searching for new knowledge. Believe in yourself despite nobody do not believe to you. Because success do not come overnight, but daily efforts always bring results.

As the saying goes, «Knowledge is the greatest wealth that elevates a person». Dreams become reality only in the hands of those who believe in them and continue working toward them. I want to be one of those people. I strongly believe that my efforts today will become the foundation of my achievements tomorrow, and one day I will study at one of the world’s leading universities and use the knowledge and experience I gain to make a contribution to the progress of my homeland.