Irrigation Season Research Articles

Basin Runoff Responses to Climate Change Using a Rainfall-Runoff Hydrological Model in Southeast Australia

The effects of climate change have been observed in the Murrumbidgee River basin, which is one of the main river basins in the southeast region of Australia. The study area is the largest and most important agricultural production area within the Murray Darling Basin (MDB). It produces more than AUD 1.9 billion of agricultural products annually and accounts for about 46% of Australia’s total agricultural production. Since Australia’s economy largely depends on its natural resources, climate change adversely impacts the economy in various ways. According to the Intergovernmental Panel on Climate Change’s fifth assessment report (IPCC, AR5), the adaptive capacity and adaptation processes have increased in Australia. The country has implemented policies and management changes in both rural and urban water systems to adapt to future drought, unexpected floods, and other climatic changes. In this study, future catchment runoff has been estimated using the hydrological model, Simplified Hydrolog (SIMHYD), which is integrated with data from three different General Circulation Models (GCMs) and future emission scenarios. Two different representative concentration pathway (RCP) emission scenarios, RCP 4.5 and RCP 8.5, have been used to obtain downscaled future precipitation and evapotranspiration data for the period of 2016 to 2100. Modeling results from the two emission scenarios showed an anticipated warmer and drier climate for the Murrumbidgee River catchment. Runoff in the Murrumbidgee catchment is affected by various dams and weirs, which yields positive results in runoff even when the monthly rainfall trend decreases. The overall runoff simulation result indicated that the impact of climate change is short and intense. The result of the Simplified Hydrolog (SIMHYD) modeling tool used in this study under the RCP 4.5 scenario for the period 2016 to 2045 indicates a significant future impact from climate change on the volumes of runoff in the Murrumbidgee River catchment. For the same period, the climate change prediction showed a decrease in total annual rainfall within the range of 2% to 62%. This reduction in rainfall is projected to decrease river runoff in the upper catchments (e.g., Tharwa, and Yass) by 17% to 58% over the projected periods. However, the runoff trends in the lower sub-catchments (e.g., Borambola) have increased by 137% to 87% under RCP 4.5 and RCP 8.5, respectively. This increasing potential runoff trend in the lower Murrumbidgee catchments gives an indication to build irrigation dams for dry season irrigation management.

Efficiency of drip irrigation technology of cotton in saline soils of Bukhara oasis

This article presents the results of scientific research on the use of cotton drip irrigation technology in conditions of water scarcity, saving water resources, assessing the growth and yield of cotton. At the same time, the technology of drip irrigation in the cultivation of the “Bukhara-102” variety of cotton was compared with the options grown in the traditional way. During the experiments, in the control field for the cultivation of the Bukhara-102 variety of cotton, i.e. in the 1st variant, which was irrigated by land invasion, irrigation was carried out 5 times during the growing season according to the scheme 1-3-1. 1240 cbm·ha-1, the seasonal irrigation norm, was 4780 cbm·ha−1; in drip irrigation in variant 2, the irrigation regime was 8 times. The cotton was irrigated according to the scheme 2-5-1. During the period of cotton growing and irrigation, irrigation works were carried out at the rate of 462-488 cbm·ha−1 and seasonal irrigation at the rate of 3339 cbm·ha−1. Less water was used in 1916 cbm·ha−1. When the effect of drip irrigation technology on the yield of cotton was studied, the yield of cotton in the first variant was 3.58 t·ha−1, while in the second variant of drip irrigation was 4.49 t/ha−1. This is 0.91 t·ha−1 higher than the control variant.

Assessment and mechanism analysis of plant salt tolerance regulates soil moisture dynamics and controls root zone salinity and sodicity in seasonally irrigated agroecosystems

Soil water deficit and saline-alkaline stress impose severe constrains to agriculture and vary across different salt-tolerant crops. Yet, the effects and mechanisms of plant salt tolerance on long-term soil water budget and future root zone (both primary and secondary) salinization and alkalization trends under changing environments in irrigated agroecosystems have not been fully understood, particularly driven by seasonal irrigation practices and stochastic climate conditions. Here, we introduce a robust species-dependent soil water, salinity, and sodicity coupled model that enables explicitly simulation to the feedback between evapotranspiration and salinity being shaped by plant salt tolerance and saturated hydraulic conductivity as affected by salinization and alkalization in seasonally irrigated agroecosystems. Using this model in conjunction with field comprehensive measurements from a typical arid inland river basin in Northwest China, we find that the species-dependent model performed well in simulating the root zone moisture (s), salinity (Cs) and sodicity (Ex) dynamics as driven by seasonal irrigation and random precipitation under different salt-tolerant crops, with average consistency measure (CM) reaching to 0.825 ± 0.017, 0.819 ± 0.027 and 0.728 ± 0.033, respectively. Stochastic simulations indicate that plant salt tolerance plays a predominant role in regulating the feedback of vegetation on soil water budget and root zone salinity and sodicity levels over time in seasonally irrigated agroecosystems. In contrast to salt-sensitive species, salt-tolerant plants seems to exhibit higher efficiency in water extraction from soil, with higher evapotranspiration rates, less frequent leaching events and greater capillary upflow fluxes, thereby lowering soil moisture and boosting salinization and alkalization in the root zone, particularly in arid climates. Sensitivity analysis revealed that plant salt tolerance, together with climatic forcing and anthropogenic perturbations, can significantly modulate the soil water balance and determine the possible trends of root zone salinization and alkalization in future, thus controlling potential risks of soil degradation related to reducing soil hydraulic conductivity Ks(Cs, Ex) in irrigated agroecosystems. Notably, since Ks(Cs, Ex) decreases with plant salt tolerance increases, salt-resilient species have the potential to exacerbate soil degradation. Our results emphasize the importance of comprehensively considering plant salt tolerance for assessing the sustainability of agricultural management practices and environmental protection measures, as well as proposing adaptive strategies under global changes.

Incorporating temperature into seepage loss estimates for a large unlined irrigation canal

Quantifying seepage losses from unlined irrigation canals is necessary to improve water use and conservation. The use of heat as a tracer is widely used in quantifying seepage rates across the sediment–water interface. In this study, field observations and two-dimensional numerical models were used to simulate seepage losses during the 2018 and 2019 irrigation season in the Truckee Canal system. Nineteen transects were instrumented with temperature probes and stage recording devices for inverse modeling to derive seepage flux and volumetric losses over the 39 km length of canal. The numerical models for each transect were calibrated and validated using the two-year dataset. Soil zones and observation data were used in each numerical model to help guide calibration of vertical and lateral heat and fluid fluxes. Model simulations were used to derive multivariable regression equations that consider stage, temperature, and hydraulic gradient. The results demonstrate the value of long-term datasets that illustrate the seasonality of groundwater levels, siltation, stage, and temperature on seepage rates. Seepage rates estimated by the numerical models range from 0.16 to 4.6 m3/d m−1. Total annual volumetric losses estimated for 2018 and 2019 were 1.6 × 10-2 to 1.2 × 10-2 km3, respectively. The seepage losses estimated by this study account for 32 % to 41 % of the inflow volumes. Regression models were able to reproduce seepage time-series simulated by the numerical models reasonably well. In arid environments, water diverted into irrigation canals may be influenced by seasonal variations in temperature sufficient to influence the water accounting of conveyed surface flows.

Sedimentary Characteristics of Shallow Aquifers and Suitability to Irrigation in the Drought Season: The Case of the Fruit Tree Area in Ben Tre Province, Mekong River Delta

In Ben Tre province, shallow groundwater found at a depth of 8 to 60 m is exploited for domestic use and for irrigation of crops in rural areas. The water wells have different depths and are usually moderately to high contaminated with iron alum, moreover the saline- brackish water is at different depths and locations. In recent years, due to the effects of climate change and drought, the problem of drinking water and irrigation for planting is an urgent need. The study determined the distribution characteristics of aquifers, the environment for forming sediments and analyzed some chemical indicators of water for crop irrigation. This study shows that shallow groundwater is clarified and consisting of the Holocene (qh) and upper Pleistocene (qp3) aquifers from 8 to 60 m in depth. The Holocene aquifer consists of fresh water commonly found at of 8.5-17.5 m in depth, and saline- brackish water appearing by layers and lenticular are commonly found at about 25- 35 m in depth. Fresh water is usually found in the fluvial flat, channel and estuary facies, and saline - brackish water is in the tidal flat, delta front and pro-delta facies belong to the subaqueous delta plain. It suggests that sedimentary facies in boreholes and geological cross-sections play an important role in determining distribution characteristics and water quality, clarifying the distribution of fresh and saline water in Holocene sediments in the study area. This result can be referenced for research in the Mekong River Delta and other regions. Shallow aquifers have not great thickness, uneven water quality, cannot provide concentrated water. However, the water source has an important meaning in providing water for agricultural irrigation in the drought season, especially in the fruit tree area in Ben Tre Province.

Performance assessment of subsurface drainage systems in the Harran Plain of the South‐East Anatolian region of Turkey

AbstractThe purpose of performance assessment of subsurface drainage systems is to achieve efficient and effective system performance by providing relevant feedback to the management of the drainage system at all levels. Therefore, it assists management in determining whether performance is satisfactory and, if not, what corrective actions need to be taken and where to rectify the situation. In this study, approximately 30% of the drainage systems built in the Harran Plain were monitored during one irrigation season in 2017. The fluctuation of the water table was measured daily at a total of 33 subcentres. In addition, electrical conductivity (EC) and pH values were measured by taking water samples from six collectors once a week. Drain flow measurements were carried out at three collector outlets. According to the SEW30 (sum of excess water at depths less than 30 cm) indicator, 82% of the monitored areas had good, medium‐good drainage and moderate drainage. The seasonal average water table depth of the monitored area was found to be approximately 120 cm. The data show the existence of a drainage system that creates an aerated soil layer suitable for all shallow‐ and deep‐rooted, water‐resistant, and sensitive plants in all of the monitored areas. Generally, the salinity of drainage water is much higher than that of irrigation water. This value was up to 25 times higher in some collector outlets. This finding has raised suspicions that salty groundwater is being pumped into the drainage system.

CHARACTERISTICS OF LOCAL PUMP SCHEMES REUSING DRAINAGE WATER IN A MAJOR RICE-BASED IRRIGATION AND DRAINAGE AREA IN THE RED RIVER BASIN, VIETNAM

A comprehensive study was undertaken in a major rice-based irrigation and drainage area, with the objective of assessing the characteristics and importance of the wide-spread use of drainage water from canal irrigation schemes by local schemes. The irrigated area of 18,308 ha consisted of the public managed Cau Son canal scheme and 208 electric-powered pump schemes, of which 109 were classified as drainage reuse schemes using drainage water from the canal scheme. The reuse pump schemes covered 27% of the irrigated area, including 6 public and 103 local managed pump stations, the latter with about 21,000 households engaged in reuse irrigation. The local schemes were typically 25 years old and showed a high degree of variability in irrigated area, total dynamic head, design capacity, and energy use. The seasonal irrigation delivery ranged by a factor 10 with about 65% “lost” in return flow mostly as surface drainage. The use of electric power was excessive, associated with low pumping and irrigation efficiencies related to poor maintenance, inadequate water management and capacity overdesign. A significant scope was identified for improved use of water and energy and for integrating local reuse schemes in performance evaluations and water management frameworks in canal-irrigated areas.

Effects of Soil Data Accuracy on Outputs of Irrigation Scheduling Tools

Highlights The effects of soil data accuracy on estimated water fluxes by an irrigation scheduling model were investigated. Free and frequently used web soil survey (WSS) soil textural data underestimated sand particles in 89% of cases. Forty-nine percent of the estimated differences in seasonal irrigation based on WSS and measured soil data were within ±25 mm. In most cases, use of WSS data resulted in larger evaporation, smaller deep percolation, and larger runoff compared to those based on measured soil data. Abstract. A widely used irrigation scheduling method is based on modeling soil water balance, which requires several key inputs, including soil data. Many scheduling tools developed using this method rely on publicly available soil data, such as the United States Department of Agriculture's Web Soil Survey (WSS). While soil survey data are a valuable source of information for general farm and natural resource planning and management at large scales, inaccuracies in soil conditions at field and subfield scales can hamper efficient agricultural water management through irrigation scheduling tools. To illuminate the implications of the localized inaccuracies, this study estimated the errors in WSS soil textural data at 18 sites in three regions of western Oklahoma through comparison with in-situ sampling (ISS) data. The effects of errors on estimated water fluxes were also investigated for dominant crops of each region over a 15-year (2006-2020) period. The findings demonstrated that WSS soil textures were finer than ISS at most sites and soil layers, resulting in generally greater root zone total available water estimates. Differences in seasonal irrigation demand estimates when WSS data were used instead of ISS reached 20% at one site but were within ±9% among the regions. Half of the estimated seasonal irrigation differences for all sites, years, and crops were within ±25 mm. Soil evaporation, deep percolation, and runoff fluxes were also impacted by soil data source, albeit to a smaller degree than irrigation, at levels and directions (over or underestimation) that were dependent on the sign and magnitude of WSS errors, as well as precipitation amounts and timing. Overall, errors in WSS data may not have a major impact at regional scales, but the effects on individual irrigated farms may be severe depending on the magnitude of difference between WSS data and true soil conditions. Keywords: Irrigation demand, Soil water balance, SSURGO, Water fluxes, Web soil survey.

Technical and technological Solutions for environmentally safe Irrigation with wide-reach Sprinklers

It is known that sprinkling can cause surface runoff of irrigation water and water erosion of soils, which leads to deterioration of water-physical and agrochemical properties of soils, its fertility decreases. The purpose of the research was to ensure environmentally safe irrigation with wide-reach sprinklers by improving the designs of sprinklers and their placement along the pipeline. The developed sprinklers were equipped with sprinklers “Frigate” DMU-B463-90. Studies have shown that the volume of surface runoff of irrigation water during the irrigation season when watering with sprinklers with developed sprinklers was less, and as a percentage of the irrigation norm was: in 2020, when watering DM with sprinklers having a rotating deflector – 6.3%, when watering with a machine with sprinklers having a double deflector – 3.9%; in 2021 respectively – 6.6 and 4.1%, in 2022 – 6.0 and 3.9%. The conducted studies allowed us to recommend installing sprinklers with a rotating deflector or cascade versions at high irrigation rates in the end part of the machine.

Transport capacity of flow in earthline channels

The theory of river flow transport is the major cause of the development of the irrigation sector and largely determines the stability of the irrigation scheme. Crop water requirements vary due to climate and crop growth stages. For this reason, the flow of sediments changes during the irrigation season. In this article, to evaluate the canals’ carrying capacity, research in natural field conditions was carried out in the Amuzang canal belonging to the “Amu-Surkhan Irrigation Systems” basin administration. Flow transportability in natural channels was calculated for particles with d=0.05 mm by S.Kh.Abalyans, A.Zamarin, A.M.Arifzhanov, and Engelund and Hansen methods. A histogram of the dependence of flow capacity, channel depth, and average speed on the Amuzang channel was obtained, according to which it was determined that the flow capacity is 1.5-1.8 kg/m3 in the range of 0.6-0.8 m/s.

ОЦЕНКА МИНЕРАЛИЗАЦИИ ДРЕНАЖНОГО СТОКА С ОРОШАЕМЫХ УГОДИЙ ОТНОСИТЕЛЬНО ФОНОВОЙ КОНЦЕНТРАЦИИ В ВОДЕ ЕСТЕСТВЕННОГО ВОДОПРИЕМНИКА С ПРИМЕНЕНИЕМ ФУНКЦИИ ЖЕЛАТЕЛЬНОСТИ ХАРРИНГТОНА

Purpose: development of methodical approach to assessment of drainage runoff mineralization from irrigated lands before discharge into a natural water body using the Harrington desirability function. Materials and methods. The object of study is the drainage water intakes of the Bagaevskaya irrigation system. The subject of the study is methodology and tools for studying the wastewater mineralization. The protocols of measurements of waste and natural water samples for the 2004–2020 irrigation season, statistical reporting data on the actual discharge of substances for the 2008–2012 irrigation season were used for calculations. General scientific methods of cognition, statistical analysis tools and properties of Harrington's desirability function are used. Results and discussion. To convert empirical data, range of values of particular indicators corresponding to the general approaches used in assessing the ecological situation of territories, and the normalization principles of anthropogenic impacts were determined. A map of the spatial distribution and temporal dynamics of the desirability of drainage runoff demineralization from collector canals within the Bagaevskaya irrigation system over the observation period was constructed. It was concluded theoretically that to eliminate the negative impact of drainage flow coming from collector canals on water bodies, it is necessary to reduce the dry residue mass by 754 tons over the specified period. Conclusions. The resulting equation makes it possible to determine the degree of desirability of drainage runoff demineralization before its discharge into a water body in terms of Harrington’s desirability function. The use of Harrington method makes it possible to build a “map” of drainage runoff “pollution” distribution within the area of controlled irrigated plots, to assess the need for demineralization and to make a generalized forecast.

The effectiveness of use of water-saving technologies against erosion in hilly areas land

Reducing irrigation erosion is one of the major challenges in the world today. Particular attention is paid to the development and maintenance of soil fertility and the development of irrigation water-saving technologies. Soil erosion due to over-irrigation of arable land on farms leads to increased fertilizer consumption and decreased productivity. The washing of the fertile layer of soil not only affects the yield of crops but also affects the mechanical composition of the soil. Erosion destroys the natural topsoil, and a reduction in organic matter accompanies this. When erosion occurs, soil particles are lost, and organisms, mineral fertilizers, and nutrients are lost along with them. Currently, the average soil washing before irrigation in such an area is 51 t/ha per year, of which nutrients are: humus 590 kg/ha, nitrogen, and phosphorus -50 and 82 kg/ha, potassium 140 kg/ha, and small elements 33 kg/ha. e. Of these, 600 thousand are currently strongly washed soils - 39 thousand, average washed - 215 thousand, and weakly washed soils - 346 thousand. As a result of soil washing and lowering the quality of wetting of sloping lands, the gross yield of 28-47 % decreases in crop areas. Resolutions decree of the President-4919 of December 11, 2020, “On measures to further accelerate the introduction of water-saving technologies in agriculture”, as well as Resolution No. PF-6024 of July 10, 2020, of the President of the Republic of Uzbekistan The program of decrees “Concept for 2030” is being implemented. With economic irrigation technology using K-9 polymer in furrow irrigation, the water use coefficient in irrigation changed from 0.78 to 0.87 in furrows, from 0.7 to 0.76 under control. The water economy during the irrigation season is 400-878 m3/ha. Fuel economy in plowing was 3-4 liters per hectare. The number of swimmers has halved. K-9 polymer using furrow irrigation increased yields from 28.4 to 68.4 and 70 quintals per hectare.

Attributing synergies and trade-offs in water resources planning and management in the Volta River basin under climate change

To feed the growing population, achieve the Sustainable Development Goals, and fulfil the commitments of the Paris Agreement, West African countries need to invest in agricultural development and renewable energy, among other sectors. Irrigated agriculture, feeding millions of people, and hydropower, generating clean electricity, depend on water availability and compete for the resource. In the Volta basin, the planned 105 000 ha of irrigated land in Burkina Faso and Ghana could feed hundreds of thousands of people. However, irrigation in the dry season depends on upstream dams that change the river’s flow regime from intermittent to permanent, and at the same time irrigation water is no longer available for hydropower generation. Using an integrated eco-hydrological and water management model, we investigated the water demand and supply of three planned irrigation projects and the impacts of the planned Pwalugu multi-purpose dam on the hydropower potentials and water availability in the entire Volta basin. We found that future irrigation withdrawals would reduce the hydropower potential in the Volta basin by 79 GWh a−1 and the operation of Pwalugu by another 86 GWh a−1. Hence, Pwalugu contributes only about 101 GWh a−1 of its potential of 187 GWh a−1. Under climate change simulations, using an ensemble of eight bias-adjusted and downscaled GCMs, irrigation demand surprisingly did not increase. The higher evaporation losses due to higher temperatures were compensated by increasing precipitation while favouring hydropower generation. However, water availability at the irrigation site in Burkina Faso is clearly at its limit, while capacity in Ghana is not yet exhausted. Due to hydro-climatic differences in the Volta basin, the cost of irrigating one hectare of land in terms of lost hydropower potential follows a north-south gradient from the hot and dry north to the humid south. Nevertheless, food production should have priority over hydropower, which can be compensated by other renewables energies.

Установление уровня деградации воды участков водных объектов, используемых для отведения дренажно-сбросных вод с орошаемых земель

Purpose: to determine the level of water degradation in the areas of water bodies used to divert drainage and waste water from irrigated lands of the Central irrigated district of Rostov region. Materials and methods. The object of study was the drainage and waste water inlets – sections of the Sal, the Salt, the Podpol’naya, the Western Manych rivers and the Beshenny yerik. The assessment of water quality in the background section line of the water body and in the section of drainage water inlet from irrigated lands was conducted according to the specific combinatorial water pollution index (SCWPI) and the complex indicator of anthropogenic load. Results. According to the SCWPI, water in the Salt river and the Besheny yerik is assessed as polluted, 3rd class, category “a”, in the background section line of the Sal river – as the 3rd class, category “b”, very polluted, in the outlet section line of drainage and waste water – as the 4th class, category “a”, dirty. The intraseasonal dynamics of the anthropogenic load index for the studied watercourses showed that in the Salt, the Podpol’naya, the Western Manych rivers throughout the entire irrigation period, the self-cleaning ability of water bodies is higher than the rate of degradation processes. The depletion processes prevail over the recovery process in the Sal river and the Besheny yerik in the study area. Conclusions. It has been determined that the complex indicator of anthropogenic load exceeds the conditionally normative indicator in the estimated section of the Sal river by more than 3 times, this indicates the damage to the aquatic environment from the drainage and waste water discharge. The rest of the studied river ecosystems are in their natural state, do not experience or experience weakly anthropogenic impact from water pollution. In certain periods of the irrigation season, the river ecosystem of the Besheny yerik experiences a short-term moderate anthropogenic load.

Moister soils at elevated CO2 stimulate root biomass but suppress aboveground biomass production in Lolium perenne

Context Increases in atmospheric carbon dioxide concentration ([CO2]) drive increases in biomass production via impacts on photosynthesis and water use. In grasslands, the scale of this stimulation is related to soil water availability. Recently, it has become clear that the way precipitation controls elevated CO2 (eCO2) effects on grassland biomass is strongly seasonal but no mechanism yet exists to explain these observations. Aims The aims of this study were to determine how seasonal water availability affects aboveground, belowground and total biomass responses of a perennial ryegrass pasture to [CO2]. Methods We established the TasFACE2 experiment in a well-fertilised perennial ryegrass (Lolium perenne) monoculture with four seasonal irrigation schedules and three [CO2]. Key results The total biomass production of perennial ryegrass pasture was strongly stimulated by eCO2, but this extra biomass was preferentially allocated to belowground growth. The relationship between soil water content and aboveground biomass varied seasonally but there was a strong positive relationship between soil water content and root biomass production in all seasons. Conclusions Increases in soil moisture caused by eCO2 contributed to increases in root growth, but root biomass production was also stimulated directly by eCO2. Restriction of irrigation, therefore, suppressed the belowground response to eCO2 and created a non-linear response of biomass to CO2 concentration. Implications Antagonistic above- and belowground responses mean that the rising [CO2] might not increase pasture production in the manner generally predicted.

Problems of climate change and efficient use of water resources in the Aral region

This artiсle рresents the results of sсientifiс researсh on сlimate сhange in the Aral Baу region due to global сlimate сhange and inсreasing water sсarсitу, as well as the develoрment of сotton irrigation methods taking into aссount soil-hуdrogeologiсal сonditions. In the Reрubliс of Karakalрakstan, whiсh is loсated in the Aralboуi region, global сlimate сhange рaрametрlaрin Biр diversitу and T-test analуsis revealed an inсrease in aсoсida air haрoрathу bу 1.42°C, and the sсientifiс-based irrigation рroсedure of сotton “Methodologу of сonduсting field exрeriments” of the Sсientifiс Researсh Institute of Cotton Seleсtion, Seeding and Cultivation Agroteсhnologies (2007 )” on the basis of the VIII hуdromodule with the largest area in the region was develoрed for the region, and it was found that irrigating сotton 4 times in the 1-2-1 sсheme with irrigation norms of 623-882 m3/ha and seasonal irrigation norms of 2789-2867 m3/ha is highlу effeсtive.

Combining Soil Water Content Data with Computer Simulation Models for Improved Irrigation Scheduling

Highlights Stand-alone irrigation scheduling models were compared to models combined with soil water content data. Use of soil water content data reduced irrigation recommendations compared to stand-alone models. Cotton fiber yield and water productivity were often not significantly impacted by the reduced irrigation amounts. Weather station aridity and other measurement uncertainties must be addressed to improve the methodology. Abstract. Irrigation scheduling models can be used to guide irrigation management decisions, but their simulations often deviate from reality. Combining in-season field data with models may improve the simulations, leading to better irrigation decisions and improved agronomic outcomes. The objective of this study was to evaluate cotton fiber yield and water productivity outcomes from a field trial that compared three computer simulation models for irrigation scheduling: (1) AquaCrop-OSPy (AQC), (2) the CROPGRO-Cotton module within the DSSAT Cropping System Model (CSM), and (3) the pyfao56 evapotranspiration-based, soil water balance model (FAO). Six irrigation scheduling treatments were established, including the three models used as stand-alone scheduling tools (AQC, CSM, and FAO) and the use of the three models in combination with weekly soil water content (SWC) data from neutron moisture meters (AQCSWC, CSMSWC, and FAOSWC). Two cotton varieties were also evaluated (NexGen 3195 and NexGen 4936). The field trial was conducted during the 2021 and 2022 cotton growing seasons at Maricopa, Arizona. Seasonal irrigation amounts were different among irrigation scheduling treatments (p < 0.05), with 9–21% less water recommended for the AQCSWC, CSMSWC, and FAOSWC treatments as compared to AQC, CSM, and FAO. In 2021, the differences in irrigation amount did not lead to any statistical differences in fiber yield among irrigation treatments, but water productivity for the stand-alone CSM model was significantly reduced compared to the other five irrigation treatments (p < 0.05). In 2022, treatments based on soil water content data reduced yield by 15% as compared to stand-alone model treatments, but the reduction was significant only for FAOSWC. Water productivity differences in 2022 were due to the choice of model rather than the inclusion of soil water content data. In both years, the shorter-season cotton variety (NexGen 3195) yielded greater than the longer-season variety (NexGen 4926), and the former achieved greater water productivity than the latter through the yield improvements (p < 0.05). Taken together, the results suggest that combining soil water content data with irrigation scheduling models was useful for reducing irrigation amounts while often maintaining cotton fiber yield and water productivity; however, issues with weather station aridity and other measurement uncertainties must be addressed to improve the methodology. Keywords: Cotton, Evapotranspiration, Irrigation, Management, Sensor, Simulation, Water.

Water Consumption and High Temperature Tolerance in Cultivation Using Different Irrigation Methods of Developed, New and Prospective Varieties of Cotton in the Conditions of Barren Grass Soils

The article presents the results of field experimental research on selection of regionalized, new and promising varieties of cotton suitable for root system drip irrigation (TS) and their maintenance based on drought-resistant and resource-efficient technologies in the conditions of barren soils of old irrigated meadows of Surkhandarya region. In the conducted research, cotton varieties Bukhara-102 (control), Sultan, Istiqlal14, SP-1601, Surkhan-106 were watered before irrigation with respect to the limited field moisture capacity (ChDNS) in the control variants of 7070-60 percent, drip irrigation. and in the experimental options of irrigation, field studies were conducted on irrigation at 65-70-65 and 70-75-65 percent. As a result, in the southern climatic region of our Republic, the optimal irrigation procedure, irrigation rate and seasonal irrigation rates, as well as indicators of high temperature tolerance, were studied in the irrigation of local regionalized, new and promising varieties of cotton.

Effects of different salinity levels in topsoil on the growth, development and yield of winter wheat

In this article, winter wheat varieties “Andijan-2” and “Andijan-4” were fed with mineral fertilizers under the conditions of irrigated, salinized, light gray soils of different degrees of salinity in the Syrdarya region of Uzbekistan. Compared to the control option, the volume mass of the soil increased by 0.02-0.03 g/cm3, the porosity of the soil decreased to 0.4-1.2%, and the water permeability of the soil increased to 3.8-23.6 m3/ha. Depending on the level of salinity, it was found that 2.2-2.5 centners of additional grain yield was obtained between the open and cotton rows of “Andijon-2” and “Andijon-4” varieties of winter wheat on soils with different levels of salinity with mineral fertilizers at different rates. The standard of seasonal irrigation of winter wheat planted between open and cotton rows was 2850-3050 m3/ha, water consumption was 98.9 m3/ha in the open field without salinity, and 87.4 m3/ha in the field planted between cotton rows. In accordance with the above, it was 118.3 and 106.1 m3/ha in the field with low salinity, and 194.3 and 173.9 m3/ha in the medium salinity field. In the maintenance of winter wheat varieties “Andijon-2” and “Andijon-4” on soils with different degrees of salinity, compared to the non-saline field, the net profit was 105,992 UZS and the rate of profitability increased to 16.1%.

Development of scientific-based irrigation systems on hydromodule districts of ghoza in irrigated areas of bukhara region based on computer technologies

Аbstract. In this article, due to year-by-year global climate change and the increase in water shortage, the water demand for cotton in the Bukhara region was developed based on FAO methodology, i.e., CropWat 8.0 model program, taking into account soil-hydrogeological conditions the results of scientific research are presented. Water-saving, scientifically based irrigation procedures for cotton irrigation were developed according to the generally accepted scale of hydromodular regions N.F. Bespalov. The seasonal irrigation norms of cotton in the Bukhara region by hydromodule regions were 3900 (VIII) - 7200 (I) m3/ha.