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 VOLUME Vol.05 Issue04 2025 

PAGE NO. 31-36 

DOI 10.37547/ajahi/Volume05Issue04-08 

 
 
 
 

Using the Modern Method in Determination of The 

Irrigation Regime of Cotton in The Republic of 

Karakalpakstan 
 

Matyakubov Bakhtiyar Shamuratovich 

Professor of National Research University "Tashkent Institute of Irrigation and Agricultural Mechanization Engineers", Uzbekistan 

 

Tlegenova Arzayim Maratovna 

Doctoral student of Karakalpak Institute of Agriculture and Agrotechnologies, Uzbekistan 

 

 

Received: 28 February 2025; Accepted: 29 March 2025; Published: 30 April 2025 

 

Abstract: The article presents data on cotton irrigation planning, taking into account soil and hydrogeological 
conditions, natural and climatic factors of the region, and the cultivated variety. The study was conducted in 
response to the year-on-year increase in water scarcity in the Republic, including the Republic of Karakalpakstan. 
Existing meteorological indicators and the FAO methodology “CropWat 8.0” program were used to plan cotton 
irrigation based on water demand. The scientifically based irrigation regime for cotton, developed by N.F.Bespalov 
based on the standard hydromodular zoning scale, according to the recommendations of scientists who 
conducted research in the conditions of the Republic of Karakalpakstan, provides for irrigation of cotton during 
the growing season in the northern zone: 3400 (IX) - 6400 (I) m3/ha and in the southern zone: 3800 (IX) - 7000 (I) 

m3/ha. Within the framework of FAO's “ CropWat 8.0“ methodology program, the cotton irrigation regime is 
planned using meteorological data from the region.   

 

Keywords: Republic of Karakalpakstan, cotton, FAO methodology, "CropWat 8.0" program, soil, hydrogeology, 
irrigation regime, hydromodular area, irrigation rate. 

 

Introduction: According to the forecasts made as a 
result of the analytical study of scientific research by 
scientists, by 2080 it is expected that, despite the 
efficient use of irrigation water, appropriate 
experiments will be carried out to meet the water 
needs of crops. The observation of water scarcity 
worldwide, changes in the form of precipitation, global 
warming of air temperature, and ensuring adequate 
water supply for the growing season of crops are of 
great importance. Currently, the observation of high 
temperatures, hail, extreme heat, low precipitation, 
and extreme weather events during drought periods 
have limited the possibilities of irrigated areas for 
growing agricultural crops. With a further increase in 
air temperature, river runoff decreased, as a result of 
which the influence on rivers and small streams 
became relatively significant, and the variability of 
runoff in all basins increased. None of the considered 

climate warming scenarios predict an increase in 
available water resources; under the conditions of the 
expected climate warming, an increase in total 
evaporation will cause an increase in water losses in 
irrigated areas, which will require additional water 
consumption. [1, 2].  

Climate change leads to 10-15% more water 
evaporation from water surfaces, and 10-20% more 
water consumption due to evaporation from plants and 
increased irrigation rates. This leads to an increase in 
non-renewable water consumption by an average of 
18%. Assessment of the possible increase in water 
consumption on irrigated lands due to climate change 
(water consumption of various crops, losses, changes in 
the melioration state of lands) is one of the urgent tasks 
of today. [3, 4].  

The main water source of the Republic of 

 

https://doi.org/10.37547/ajahi/Volume05Issue04-08
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American Journal Of Agriculture And Horticulture Innovations 32 https://theusajournals.com/index.php/ajahi 

American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559) 
 

 

Karakalpakstan is the Amu Darya River, the lower part 
of which is located in the Aral Sea. [5, 6]. 

In the water management sector of the Republic of 
Karakalpakstan, an extremely serious and high 
shortage of irrigation water is observed year after year, 
and due to the growing demand for water for 
agricultural crops, including cotton, as a result of 
climate change, the efficient use of water in agriculture 
remains a priority area. Periodic data on the analysis of 
precipitation in the Republic of Karakalpakstan show 
that the amount of precipitation in the northern and 
southern regions for 2024 is 67-77 mm [7]. Therefore, 
determining the water requirements of agricultural 
crops, including cotton, in various climatic and soil-
hydrogeological conditions of the Republic of 
Karakalpakstan based on the FAO methodology using 
the "CropWat 8.0" program is one of the urgent tasks. 

METHODS 

The water demand of crops was determined by the 

Penman-Monteth method of evapotranspiration (ET0) 
of individual agroecological units based on the 
"SropWat 8.0" program developed by FAO [8]. The 
research used methods of system analysis and 
mathematical statistics, as well as the "Methods of 
Conducting Field Experiments" of the Research 
Institute of Irrigation and Agricultural Mechanization 
[9]. 

RESULTS AND DISCUSSION 

Hydromodular zoning of irrigated lands of the Republic 
of Karakalpakstan was carried out (Table 1).  For each 
hydromodular region, a scientifically based irrigation 
regime for cotton was developed according to the 
"SropWat 8.0" program. Currently, developing cotton 
irrigation regimes and water distribution planning using 
modern computer programs is relevant in conditions of 
increasing water scarcity observed year after year [10, 
11]. 

Table 3 

Regime of cotton irrigation by hydro-modular regions in the Republic of Karakalpakstan 

 

Hydromodula

r region 

Number of 

irrigations, 

times 

Irrigation 

norms, 

m3/ha 

Seasonal 

irrigation 

rates 

Irrigation timing 

beginning ending 

 Northern region 

I 8 700-1100 6400 24 V 4 IX 

II 8 500-1000 6000 26 V 8 IX 

III 8 600-850 5250 24 V 19 VII 

IV 7 600-1000 5900 3 V  24 VIII 

V 7 500-850 4900 26 IV 14 VIII 

VI 7 600-800 4500 18 V 18 VIII 

VII 7 600-700 4700 25 V 30 VIII 

VIII 6 500-700 3550 28 V 22 VIII 

IX 8 400-500 3400 31 V 26 VIII 

Southern region 

I 9 700-1000 7000 24V 21VIII 

II 8 650-1000 6400 24V 26VIII 

III 10 600-800 6200 24V 25VIII 

IV 9 700-800 6700 20V 21VIII 

V 7 650-1000 5200 1VI 1IX 



American Journal Of Agriculture And Horticulture Innovations 33 https://theusajournals.com/index.php/ajahi 

American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559) 
 

 

VI 8 650-750 5800 2VI 21VIII 

VII 7 750-850 5400 2VI 23VIII 

VIII 5 650-850 3600 4VI 20VIII 

IX 6 650-800 3800 6VI 21VIII 

In the Republic of Karakalpakstan, when developing the 
irrigation regime using the "CropWat 8.0" program of 
the Food and Agriculture Organization (FAO) 
methodology using meteorological indicators, the soil-
hydrogeological and natural-climatic conditions of the 
region were taken into account. 

Data on the natural and climatic conditions of the 
Republic of Karakalpakstan were obtained from the 

"Nukus" weather station and used for water use 
planning. Location coordinates of the "Nukus" weather 
station (State: Uzb 2024 Height of the station relative 
to the Baltic Sea: 77 m; Latitude: 42.45 °C; Length: 
59.62 °V) and the required air temperature (maximum 
and minimum temperature), relative humidity, amount 
of precipitation, wind were formed (Tables 2 and 3) and 
fully loaded into the program and launched. 

Table-2 

Water consumption of cotton for the northern territory of the Republic of Karakalpakstan. 

Months 

Air 

temperature, 0C 

Relative 

humidity, 

% 

Wind 

speed, 

m/s 

Precipitation, 

mm 

Sunshine 

duration, days 

ЕТо 

mm/day  
Мах Min 

January 3,9 -3,8 74 2,4 3,2 3,6 0,76 

February 9,6 -1,5 66 2,9 7,6 5,6 1,64 

March 16,4 1,7 37 3,3 5,2 8,9 3,63 

April 21,8 8,9 43 2,9 33,3 8,9 4,55 

May 30,9 17,3 37 2,8 18,2 11,0 6,83 

June 35,6 20,3 22 2,7 0,0 12,7 8,49 

July 37,0 22,7 29 2,7 3,2 12,7 8,53 

August 32,6 19,0 34 2,6 0,7 11,8 6,85 

September 25,8 11,3 33 2,6 0,0 11,2 5,01 

October 19,5 3,1 38 1,9 0,0 9,6 2,69 

November 7,3 -4,7 55 2,1 3,6 6,3 1,21 

December -2,0 -12,0 72 2,2 2,0 5,7 0,50 

Average 19,9 6,8 45 2,6 77,0 9,0 4,22 

 Source: Annual report of the Hydrometeorological Center. 

Table-3 

Water consumption of cotton for the southern territory of the Republic of Karakalpakstan. 

Months 
 

Air temperature, 

0C 
Relative 

humidity, % 

Wind 

speed, 

m/s 

Precipitation, 

mm 

Sunshine 

duration, days 

ЕТо 

mm/day 

Мах Min 



American Journal Of Agriculture And Horticulture Innovations 34 https://theusajournals.com/index.php/ajahi 

American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559) 
 

 

January 4,5 -3,1 66 1,4 0,9 3,6 0,76 

February 10,0 -0,6 64 1,6 7,3 5,6 1,35 

March 17,0 3,3 48 1,8 5,4 8,9 2,81 

April 23,2 10,2 46 1,7 7,9 8,9 4,12 

May 31,3 18,2 41 2,0 29 11,0 6,11 

June 36,4 21,3 30 1,7 0,0 12,7 7,31 

July 37,5 24,5 30 1,8 4,2 12,7 7,45 

August 33,2 19,6 36 1,7 2,0 11,8 6,05 

September 26,6 12,7 41 1,8 0,0 11,2 4,34 

October 19,8 4,9 46 1,7 0,0 9,6 2,55 

Novembe

r 7,8 -3,5 57 1,7 9,3 6,3 

1,17 

December -1,2 -9,9 66 1,7 1 5,7 0,55 

Average 20,5 8,1 48 1,7 67 9,0 3,71 

   Source: Data from the Hydrometeorological Service Center. 

Data on the amount of evapotranspiration, 
precipitation, amount of useful precipitation, 
maximum and minimum air temperature, relative 
humidity, wind speed, duration of solar radiation, and 
radiation in the Republic of Karakalpakstan in 2024 
were included in the program. Using the program, the 
following works were carried out, namely, the current 
and future level of development of the effective use of 

irrigation water, determining the criteria for water use 
in the process of reducing water supply through water 
conservation, the influence of irrigation water on crop 
yields, and the rational use of available water resources 
were determined. 

Reference evapotranspiration was calculated using the 
Penman-Monteth formula (Tables 2 and 3) [8]. 

   

 

 

(1) 

ЕТо - reference evapotranspiration [mm/day-1]; 

Rn- net radiation reaching the plant surface [MJ m- 2 day-1]; 

G - density of heat flow in the soil, [MJ m-2 day-1]; 

Т - average daily air temperature at an altitude of 2 m above the ground level [°C];  

u2 - wind speed at an altitude of 2 m above ground level [ms-1]; 

еs - saturated vapor pressure [kPa];  

еа - actual pressure of actual steam[kPa]; 

(еs-еа)vapor saturation pressure deficit [kPa]; 

Δ - steam pressure gradient curve [kPa °C-1];  

 - psychrometric stability (constant) [kPa °C-1] [8]. 



American Journal Of Agriculture And Horticulture Innovations 35 https://theusajournals.com/index.php/ajahi 

American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559) 
 

 

Solar radiation absorbed by the atmosphere and heat 
emitted from the earth increase the air temperature. 
Sensitive heating of the surrounding air provides the 
crop with energy and affects the evaporation rate. In 
sunny warm weather, water loss from evaporation is 
greater than in cloudy and cool weather. 

As mentioned above, reference evapotranspiration 
was calculated using the "SropWat 8" program based 
on meteorological station data near the research object 
in the Republic of Karakalpakstan. 

The irrigation regime for cotton in the Republic of 
Karakalpakstan is presented in Table 2. Crop 
coefficients were developed and adopted based on 
values recommended by the "Scientific Research 
Institute of Irrigation and Water Problems" [12]. The 
water demand of cotton in the Republic of 
Karakalpakstan, depending on the hydromodular 
region of the region, for the organization of irrigation 
during the season, in the northern zone: 3400 (IX) - 
6400 (I) m3/ha, and in the southern zone: 3800 (IX) - 
7000 (I) m3/ha (Table 1). In short-term crops, especially 
in the dry regions of the Republic of Karakalpakstan, the 
cotton's water demand during the growing season was 
high, since the indicators of the meteorological station 

in the area where these studies were conducted were 
very high and precipitation was very low. Experiments 
conducted in the conditions of the Republic of 
Karakalpakstan, as well as the "SropWat 8.0" program, 
presented by the international FAO methodology, were 
analyzed in adaptation to local conditions. 

Using the "CropWat 8.0" program of the FAO 
methodology, seasonal irrigation norms for cotton 
were developed for the objects of research. Based on 
this, the seasonal irrigation norms recommended by 
Professor N.F. Bespalov for cotton cultivation and 
developed by scientists of the Tashkent Institute of 
Irrigation and Agricultural Mechanization Engineers 
National Research Institute were compared, and a 
correlation coefficient coordinate system was 
developed. 

The correlation coefficient in cotton cultivation was 
R2=0,922 for the northern region and R2=0,9804 for 
the southern region. Each pair of values is denoted by 
a certain symbol, and these indicators are presented in 
Figures 1 and 2. It was established that the change in 
the coordinate axes "Y" and "X" has the following 
relationship (2, 3). 

 

 y = 0,6429 X + 0,7152                                (2) 

 y = 0,6594 X + 0,6452                                (3) 

Using the "SropWat 8" program, an irrigation regime 
for cotton grown in the Republic of Karakalpakstan was 
developed. With the help of the program, irrigation 
timing, timing, and irrigation rates were determined,  

taking into account the cotton's water requirements for 
the growing season. 

 

  

 

Figure 1. Coefficient of 

correlation of crop water 

consumption in the 

northern region  

 

 



American Journal Of Agriculture And Horticulture Innovations 36 https://theusajournals.com/index.php/ajahi 

American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559) 
 

 

 

Figure 2. Correlation 

coefficient of water 

consumption of crops 

for the southern region 

CONCLUSION 

1. Using the "CropWat 8.0" program, reference 
evapotranspiration was determined for the research 
object. 

2. Using the FAO CropWat 8.0 program, a scientifically 
based irrigation regime for cotton grown in the 
southern and northern regions of the Republic of 
Karakalpakstan has been developed. 

3. It was established that the correlation coefficient of 
the seasonal irrigation rate of cotton for the 
hydromodular regions of the Republic of 
Karakalpakstan is R2=0,922 for the northern zone and 
R2=0,9804 for the southern zone. 

4. Seasonal irrigation norms for cotton in the Republic 
of Karakalpakstan by hydromodular regions were 3300-
5900 m3 per hectare. 

5. According to the hydromodular regions, the 
irrigation rate of cotton in the northern zone was 500-
1100 m3 (netto) and the number of irrigations was 6-8, 
while in the southern zone it was 600-1000 m3 (netto) 
and the number of irrigations was 6-10. 

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Agaltseva, N. “The impact of climate change on the 
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United Nations Food and Agriculture Organization. 
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Khamidov, M.K., Balla, D., Hamidov, A.M., Juraev, U.A. 
“Using collector-drainage water in saline and arid 
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Matyakubov, B. “How efficient irrigation can ensure 
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