Abstract:Crop irrigation on chernozems inappropriate to ecological requirements is often accompanied by degradation changes of soils: flooding, secondary salinization and soil alkalinity, destructurization, violation of gas regime, dehumidification, etc. Thus the necessity occurred to study comprehensively the changes in agroecological state of soils, having been irrigated with mineral water under conditions of the Northern Steppe of Ukraine. It has been proved that the irrigated soil solonization is a widespread negat… Show more
“…Without irrigation, a better substitution of exchangeable sodium with calcium was observed in variants with the application of phosphogypsum at a dose calculated beyond the coagulation limit (6 tons per hectare). This aligns with previous studies [22,46,74].…”
The purpose of our research is to evaluate the agroecological condition of soils under long-term irrigation (over 50 years) and to improve existing measures to slow down degradation processes by introducing phosphogypsum. The possibility of simultaneously addressing the ecological issue of using large amounts of phosphogypsum waste and the agronomic characteristics of slowing or eliminating salinisation processes in irrigated soils has been studied and justified. The research methodology was based on the comparison of different meliorative doses of phosphogypsum under the following conditions: by the amount of exchangeable sodium that should displace calcium in the calculated soil layer; by the coagulation limit; and by the absorption norm and the corresponding amount of sodium coming with irrigation water. To determine water-soluble salts (anions, cations) and pH level, a water extract was utilized. Multi-year studies to determine the impact of phosphogypsum on irrigation-salinised soils with and without irrigation showed positive changes in the anion–cation composition of water extraction, resulting in a reduction in the degree of the salinity of these soils. It was established that in chernozem soils under irrigation, the sodium adsorption ratio decreases by 74.5% compared to the control indicators, and without irrigation, by 23%. The best results in the displacement of exchangeable sodium were observed when phosphogypsum was applied at a dose calculated by the coagulation limit without irrigation and with irrigation—by the absorption norm.
“…Without irrigation, a better substitution of exchangeable sodium with calcium was observed in variants with the application of phosphogypsum at a dose calculated beyond the coagulation limit (6 tons per hectare). This aligns with previous studies [22,46,74].…”
The purpose of our research is to evaluate the agroecological condition of soils under long-term irrigation (over 50 years) and to improve existing measures to slow down degradation processes by introducing phosphogypsum. The possibility of simultaneously addressing the ecological issue of using large amounts of phosphogypsum waste and the agronomic characteristics of slowing or eliminating salinisation processes in irrigated soils has been studied and justified. The research methodology was based on the comparison of different meliorative doses of phosphogypsum under the following conditions: by the amount of exchangeable sodium that should displace calcium in the calculated soil layer; by the coagulation limit; and by the absorption norm and the corresponding amount of sodium coming with irrigation water. To determine water-soluble salts (anions, cations) and pH level, a water extract was utilized. Multi-year studies to determine the impact of phosphogypsum on irrigation-salinised soils with and without irrigation showed positive changes in the anion–cation composition of water extraction, resulting in a reduction in the degree of the salinity of these soils. It was established that in chernozem soils under irrigation, the sodium adsorption ratio decreases by 74.5% compared to the control indicators, and without irrigation, by 23%. The best results in the displacement of exchangeable sodium were observed when phosphogypsum was applied at a dose calculated by the coagulation limit without irrigation and with irrigation—by the absorption norm.
“…As a result of long-term irrigation with water of different quality in the territory of the Northern Steppe of Ukraine, an acute problem of secondary salinization and salting of lands arose. A change in the natural state leads to the degradation of soils, their removal from their intended purpose due to the loss of fertility (Onopriienko et al, 2019).…”
Section: Resultsmentioning
confidence: 99%
“…This is explained by the arrival of SO 4 -2 ions with mineralized irrigation water and their content in phosphogypsum. The gradual decrease in the number of ions in the third year after the application of phosphogypsum is explained by the removal of the formed sodium sulfate into the lower soil horizons ( Onopriienko et al, 2019) During the research period, no corresponding dependence was observed in the change in amount of HCO 3 -1…”
The long-term irrigation of extensive areas in the steppe zone of Ukraine using low-quality and mineralized water has caused degradation processes associated with soil salinization. To mitigate or alleviate these processes, researchers investigated the potential of chemical reclamation through the application of phosphogypsum. The study took place in the northern Steppe of Ukraine near the village of Oleksandrivka, Dnipro district, Dnipropetrovsk region. Over many years, field experiments were conducted, introducing phosphogypsum as a chemical meliorant. The experimental design included the application of phosphogypsum at rates of 1.4, 3.0, and 6.0 t/ha during different periods of the year. Standardized research methods were used for sampling, laboratory analysis, and processing of the results. The research identified a high salt content (0.35-0.48%) in the arable soil layer, signs of salinization (exchangeable sodium content of 3.64%), and unsatisfactory physical condition of the soil in the research areas. The application of phosphogypsum led to an increase in sulfate anions, as observed in the soil's sulfate chemistry, while the control areas exhibited a soda-sulfate type of salinity. The pH level of the water extract remained within neutral values throughout the years of the study. Positive changes were observed regarding the degree of soil salinity. Specifically, the application of phosphogypsum at rates of 3 and 6 t/ha in irrigated areas resulted in a change from moderate to slightly saline salinity levels. The research also demonstrated a positive effect on the sodium-adsorption ratio, particularly when phosphogypsum was applied during irrigation in the third year. The sodium-adsorption ratio decreased by 69% compared to the control options, indicating a better ameliorative effect of phosphogypsum during irrigation. Under the conditions of using water of class II quality for irrigation, the optimal application of phosphogypsum was found to be at doses of 3 t/ha for spring cultivation and 6 t/ha for the main cultivation in autumn. These application rates effectively reduced the degree of soil salinity and improved the ecological and meliorational conditions of the irrigated area
“…As a result of long-term irrigation with water of different quality in the territory of the Northern Steppe of Ukraine, an acute problem of secondary salinization and salting of lands arose. A change in the natural state leads to the degradation of soils, their removal from their intended purpose due to the loss of fertility (Onopriienko et al, 2019).…”
Section: Resultsmentioning
confidence: 99%
“…This is explained by the arrival of SO 4 -2 ions with mineralized irrigation water and their content in phosphogypsum. The gradual decrease in the number of ions in the third year after the application of phosphogypsum is explained by the removal of the formed sodium sulfate into the lower soil horizons ( Onopriienko et al, 2019) During the research period, no corresponding dependence was observed in the change in the amount of HCO 3 -1…”
Рекомендовано до друку та поширення через мережу Інтернет Вченою радою Миколаївського національного аграрного університету(протокол № 9 від 25 квітня 2023 р.
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