Accumulation Of Nitrate Nitrogen Research Articles

Synergistic management of nitrogen contamination in overflow wastewater and algal proliferation in lake receiving wastewater based on electrochemical oxidation process

Urban lake eutrophication, largely driven by overflow wastewater, plays a pivotal role in precipitating algal proliferation due to heightened nitrogen levels in aquatic ecosystem. In addressing this question, this study investigated the chloride-mediated electrochemical oxidation system as a promising solution for controlling nitrogen contamination in overflow wastewater and inhibiting algal proliferation in wastewater-receiving urban lakes, and also evaluated the influence of essential operational parameters on the performance of system. The results indicated that, under the environmental conditions set by this experiment, the removal efficiency ranges of ammonia nitrogen and total nitrogen were 14.91 % - 100 % and 13.98 % - 99.62 %, respectively; meanwhile, the maximum algae inhibition rate could reach 100 % at a capacity ratio of 0.01. Response Surface Method analysis highlighted current density as the preeminent factor in nitrogen removal and algae inhibition, surpassing the influence of initial chloride ion and nitrogen concentrations within the system. Notably, an excessive current density could inadvertently lead to the nitrate nitrogen accumulation (up to 29 %), thereby diminishing the total nitrogen removal efficiency, particularly in low nitrogen-concentrated overflow wastewater scenarios. With respect to algae inhibition, a direct correlation was identified between higher residual total chlorine concentrations in the receiving lake and increased algae inhibition rates (R = 0.90, P < 0.05), and the residual total chlorine was found to exert pronounced inhibition on cyanobacteria compared to other algal forms. However, caution was advised regarding potential algal growth stimulation if the initial received total chlorine concentration in the urban lake receiving wastewater below 0.5 mg/L. These findings not only affirm the feasibility of this synergistic approach but also elucidate critical aspects for process optimization and control.

Comprehensive compositional analysis of liquid organic product prepared by industrialized hydrothermal cracking of biomass waste and its potential application as fertilizer

Hydrothermal cracking involves the conversion of organic waste into efficient fertilizer through hydrolysis at temperatures ranging from 180 to 220 °C and pressures of 1.5 to 2.45 MPa, which offers significant advantages in shortening the production cycle, enhancing efficiency, and decomposing antibiotics. As a result, it holds immense practical value for promoting organic fertilizer manufacturing processes globally. The products derived from hydrothermal cracking can be categorized into solid and liquid components. Extensive research has focused on the composition and use of solids, while studies on liquids have mainly examined basic characteristics. The study aimed to comprehensively analyze the components in liquid products prepared through hydrothermal cracking and evaluate their suitability as liquid fertilizers. Specifically, we employed rigorous analytical techniques to accurately identify and quantify medium and trace elements, organic acids, amino acids, and plant growth regulators. Furthermore, we carried out a planting experiment to assess the yield and soil changes following the application of liquid products in maize cultivation. The experimental data revealed that the liquid product contained abundant medium and trace elements, along with 6.22 g/L free amino acids and 9.22 g/L organic acids. It is noteworthy that this liquid product contained 1.22 × 105 pg/mL ABA, 6.26 × 103 pg/mL IAA, 1.07 × 102 pg/mL IBA, and 3.60 × 10−2 pg/mL GA3. The utilization of this liquid product has the potential to enhance the disease resistance of maize crops and promote the accumulation of nitrate nitrogen in the soil. By understanding the composition of liquid products via hydrothermal cracking, valuable insights can be gained into their potential benefits for agricultural and ecological applications.

Analysis of full nitrification performance and optimization of reaction properties using N and O isotope fractionation

Isotopic fractionation properties have been successfully applied to identify the distribution and fate of nitrogen in ecosystems, revealing the dynamic response of N and O elements during nitrogen transport and transformation. However, only a few studies used the dual isotope technology in activated sludge treatment of domestic wastewater and many aspects of the process are unclear. Here, we use the dual isotope techniques to increase the understanding of the substrates required for nitrification reactions, nitrification performance, and process operation. Mixed sludge was successfully enriched with nitrifying bacteria in a continuous culture, and three dissolved oxygen (DO; 0.2–0.4, 3–4, and 7–8 mg/L) and three temperature levels (18 ± 1, 25 ± 1, and 33±1 °C) were tested for efficiency of nitrate nitrogen accumulation. Both δ15NNO3 and δ18ONO3 showed a gradual increase with an increase in DO or temperature, the increase in DO slowed down the fractionation effect of isotopes, and the increase in temperature reduced the variability in N and O utilization. The slope of δ15NNO3:δ18ONO3 gradually approached 1 with the increase in DO (<7 mg/L) or in temperature, and the optimal range of DO and temperature were accurately judged to strengthen the denitrification performance of nitrifying bacteria. δ18OH2O was successfully taken up to form NO2−-N and NO3−-N with 74 and 91% replacement rates, respectively, indicating that DO and H2O jointly completed the formation of nitrate nitrogen during the long nitrification process. In summary, the in situ dual isotope technology can help optimize the influence of environmental factors on nitrification performance to guide the long-term stable operation of nitrification reactions in sludge treatment and provide a reliable basis for complex activated sludge nitrification systems.

Simultaneous selenite reduction and nitrogen removal using Paracoccus sp.: Reactor performance, microbial community, and mechanism

Selenium-containing wastewater has a high concentration of nitrogen compounds (ammonia nitrogen [NH4+-N]), leading to water pollution. Thus, the simultaneous reduction of selenium and removal of nitrogen compounds during wastewater treatment has become the top priority. However, the exogenous bacteria that can simultaneously reduce selenite and remove ammonia nitrogen and colonize in the wastewater treatment systems have not been reported. Additionally, the effects and the underlying mechanism of biofortification on the reduction and removal efficiency of the microorganisms remain unclear. In this study, we investigated the simultaneous selenite reduction and nitrogen removal efficiency of Paracoccus sp. (strain SSJ) isolated from selenium-contaminated soil and explored biofortification effects on the composition and structure of the microbial community. Using sequencing biofilm batch reactors (SBBRs), the structural and functional characteristics of the microbial community were systematically compared between the control (group A) and biofortified (group B) groups. Strain SSJ could simultaneously reduce 63.28% of selenite and remove 93.05% of NH4+-N within 24 h. Moreover, no accumulation of nitrate nitrogen (NO3−-N) and nitrite nitrogen (NO2−-N) was observed in the reaction process. The performance and stability of the SBBRs enhanced by strain SSJ were greatly improved. Illumina sequencing results showed that strain SSJ was surprisingly colonized, and Paracoccus was the predominant genus in group B (relative abundance: 13.93%). Moreover, PICRUSt2 analysis results suggested that the microbial community in group B demonstrated increased rates of ammonia nitrogen removal through ammonia assimilation and selenite reduction through sulfur metabolism and glutathione-mediated selenite reduction pathway. In summary, our findings shed light on the mechanism for simultaneous selenite reduction and nitrogen removal by biofortification and provide novel microbial resources for the treatment of selenite-containing wastewater.

The effectiveness of forms of mineral fertilisers and productivity of winter wheat on grey-meadow soils of Kyrgyzstan

Fertilisation of winter wheat is necessary to provide the crop with nutrients for optimal growth, development, and formation of the crop. However, the effectiveness of fertilisers may depend on their shape, soil conditions, and climate. The purpose of the study is to examine the effectiveness of using various forms of mineral fertilisers on the formation of productivity of winter wheat on grey-meadow soils of Kyrgyzstan. In 2019-2021, field experiment was conducted in the Educational-experimental Farm of the Kyrgyz National Agrarian University, named after K.I. Skryabin to achieve this goal. As a result of the study, it was identified that the formation of high yields of winter wheat is closely related to the use of nitrogen-containing fertilisers in crop rotation, which contributes to the accumulation of nitrate nitrogen in the soil. The substantial effect of ammonium nitrate and granulated superphosphate on the nitrogen regime of the soil was also noted. The concentration of carbon-ammonium-soluble phosphates is determined by the actions of ammonium sulphate, ammonium nitrate, and all forms of phosphorus fertilisers, but no special changes in the phosphate regime of the soil under the influence of forms of phosphorus fertilisers were identified. However, when using complex fertilisers, a slight accumulation of mobile phosphorus in the soil was noted. The introduction of ammonium nitrate ensures the yield of winter wheat grain at the level of 56 centner/ha, ammonium sulphate – 53.1 centner/ha. granulated superphosphate provided the highest level of winter wheat yield – 55.5 centner/ha and the highest increase in yield against the background of nitrogen-potassium nutrition – 8.7 centner/ha. Therefore, for winter wheat, after rowed precursors, it is preferable to apply ammonium nitrate from nitrogen forms of fertilisers. As an alternative to it – ammonium sulphate or urea, from phosphorus forms of fertilisers – granular superphosphate. The practical importance of the results of the study allows for developing more effective methods of using fertilisers and increasing the productivity of grain crops on grey-meadow soils of Kyrgyzstan and in other regions with similar soil and climatic conditions

Bio-Drying of Municipal Wastewater Sludge: Effects of High Temperature, Low Moisture Content and Volatile Compounds on the Microbial Community

This study examined microbiological processes during the bio-drying of municipal wastewater sludge (WS) from the waste treatment facilities of the Moscow region (Russia). In just 21 days of bio-drying, the moisture content of the mixture of WS and wood chips decreased by 19.7%. It was found that members of the genus Bacillus were the main organic matter destructors. In the period from 7 to 14 days, the rates of organic matter mineralization and moisture loss were the highest, and bacteria of the genus Bacillus dominated, accounting for 43.5 to 84.6% of the bacterial community with a total number of 1.20 (±0.09) × 106 to 6.70 (±0.44) × 105 gene copies µg−1. The maximum number of Amaricoccus was (15.7% of the total bacterial community) in the middle of bio-drying. There was an active accumulation of nitrate nitrogen due to the oxidation of nitrogen-containing substances during the same period of time. Bacteria of the genera Sphingobacterium, Brevundimonas, Brucella, Achromobacter and fungi of the genus Fusarium dominated in the biofilter, which removed volatile compounds from the waste air by 90%. The obtained results allow to model the further intensification of bio-drying, as well as its efficiency and safety.

Effects of soybean oligosaccharides instead of glucose on growth, digestion, antioxidant capacity and intestinal flora of crucian carp cultured in biofloc system

This study aimed to investigate the effects of soybean oligosaccharide-cultured biofloc on the growth, digestion, antioxidant capacity, and intestinal flora of crucian carp. Glucose as a carbon source was used as the control group (Con), and glucose was replaced with soybean oligosaccharides by 1 % (S1), 5 % (S5), 10 % (S10), and 100 % (S100) with C: N of 15 as the experimental group with six replicates. Compared with the Con group, the accumulation of nitrate nitrogen (NO3--N) decreased significantly (P < 0.05), and the turbidity (T·d) of water increased significantly in the S100 group. The biofloc volume (FV), weight gain (WG), and specific growth rate (SGR) were significantly increased (P < 0.05), and the feed coefficient (FCR) was significantly decreased (P < 0.05) in the S1 group. The content of malondialdehyde (MDA) in the S10 and S100 groups was significantly decreased (P < 0.05). Intestinal amylase in S10 and S100 groups was significantly decreased (P < 0.05), the lipase was significantly increased in the S10 group (P < 0.05), and the trypsin was significantly increased in the S1 and S5 groups (P < 0.05). In addition, the Chao index of intestinal microbial species richness was significantly increased in the S1 group (P < 0.05). The abundance of Pseudomonas and Vibrio decreased significantly in the S5 and S10 groups (P < 0.05). The pathways related to metabolic activities in intestinal flora in the experimental groups were significantly up-regulated (P < 0.05). Our results showed that the growth and digestion capacity of crucian carp could be improved in the biofloc system cultured by 1–5 % soybean oligosaccharides replacement of glucose, the abundance of beneficial bacteria such as Actinobacteriota in the intestine could be increased, and the abundance of harmful bacteria such as Pseudomonas and Vibrio could be decreased.

Nitrogen transfer and transformation in bioretention cells under low temperature conditions

The nitrogen removal effect of traditional bioretention cells is generally poor under low temperature conditions, with significant levels of fluctuation and leaching often reported. Therefore, the migration characteristics of nitrogen were explored in bioretention cells under low temperature conditions, with the aim of improving the nitrogen removal effect. Four groups of modified collapsible loess bioretention cells were constructed and operated at 1, 5, 10 and 25 °C. The nitrogen removal effect of the cells was determined at different temperatures and the nitrogen migration and transformation characteristics under low temperature conditions were discussed. Experimental results showed that during the rainfall period, the ammonia nitrogen removal efficiency remained similar at different temperatures (above 97 %), while the nitrate nitrogen removal efficiency varied significantly at 1, 5, 10 and 25 °C, from 28.15 %–65.22 %, 96.68 %–98.8 %, 96.75 %–98.88 % and 80.14 %–96.72 %, respectively. In addition, nitrate nitrogen accumulation occurred in the filler during rainfall events, with lower temperature conditions increasing the final concentration of nitrate nitrogen accumulated. Following a rainfall event, the content of nitrate nitrogen in the filler decreased significantly over a 60 h dry period. However, the nitrate nitrogen reduction rate was significantly lower under low temperature conditions, than at 25 °C. Overall, low temperature conditions had a negative effect on the accumulation of nitrate nitrogen in the filler during rainfall events, as well as the transformation and migration of nitrate nitrogen within the filler during drought periods, with the adverse effects most significant at temperatures lower than 5 °C.

Eutrophication of Arable Soil: The Comparative Effect of Mineral and Organic Fertilizer Systems

Agrogenic eutrophication refers to the artificial enrichment of soil with organic carbon and nutrients in result of applying mineral and organic fertilizers to increase soil fertility and plant productivity. Eutrophication of gray forest soils (Luvic Retic Greyzemic Phaeozems (Loamic)) was created by annual application of increasing doses of mineral (N 90–360, P2O5 75–300 and K2O 100–400 kg/ha) and organic (fresh cattle manure from 25 to 100 t/ha) fertilizers under plants of a 5–field crop rotation for 9 years in microplots experiment. The NPK amounts applied with the manure were approximately equal to the corresponding doses of mineral fertilizer. The rates of soil enrichment by Corg under mineral and organic fertilizer systems were, respectively, 0.29–0.38 and 0.76–1.56 g/kg per year, Ntot – 0.04–0.06 and 0.06–0.09 g/kg per year, available P2O5 – 4–57 and 11–55 mg/kg per year, available K2O – 5–44 and 6–31 mg/kg per year. The fertilizer doses under both systems were the most significant factor in the accumulation of nitrate nitrogen, available forms of phosphorus and potassium in the soil, while the Ntot contents was controlled by the duration of fertilizer application. The Corg content in the soil with organic and mineral fertilizers depended on the dose of manure and the duration of NPK application, respectively. Soil eutrophication with mineral fertilizers was accompanied by a decrease in soil pH, and eutrophication with organic fertilizers, on the contrary, led to an increase in pH. It is emphasized that over–fertilization and long–term use of fertilizers are the main factors in the development of soil eutrophication and the concomitant change in soil pH.

The Effect of Differentiated Nitrogen Fertilization using Satellite Navigation Systems on the Spring Wheat (Triticum aestivum L.) Crop Yield in the Conditions of Chernozem-Like Soils in the Northern Forest Steppe of the Tyumen Region of Russia

Soil cultivation without layers turnover impeded the process of nitrate nitrogen accumulation compared with plowing. The traditional scheme of mineral fertilization applying the averaged standard did not create a heterogeneous level of nutrient supply in primary soil cultivation systems. These factors set them in unequal conditions by default in terms of nitrogen supply to crops. Solid mineral fertilization with the use of precision farming systems in subcompartments, taking into consideration nutrient concentration in soil and the estimated crop yield changes the function of nitrogen status formation. The aim was to study nitrogen status while applying an innovative approach to primary soil cultivation using satellite navigation systems. The experiments were carried out on meadow-chernozem, and nitrogen status was studied in plowing, differentiated, subsurface tillage, and soil cultivation without layers turnover. Nitrate nitrogen was defined by the ionometric method. Moderate supply was registered in plowing and differentiated tillage in the 0-20 cm layer with 10.1-11.8 mg/kg. During the tillering phase, N-NО3 supply amounted to 16.6-15.2 mg/kg which indicated a high supply of crop plants. On fields with subsurface tillage and no primary soil cultivation, a moderate supply of nitrate nitrogen was observed-10.1-10.8 mg/kg. Innovative technology including differentiated mineral fertilization decreased spatial variability of N-NO3 supply to 8.2-10.4 mg/kg before spring wheat (Triticum aestivum L.) seeding, during tillering phase its variability dropped to 15.3%, having the benefit of accumulation with resource-saving tillage: 11.9-12.7 mg/kg. Optimization of nitrogenous nutrition in the case of differentiated mineral fertilization with precision farming systems application in off-line mode helped achieve the maximum spring wheat yield-3.63-4.03 t/ha in soil cultivation without turning over layers.

Regime of nitrate nitrogen in chernozem during the cultivation of perennial grasses

The article presents the results of field experiments to study the dynamics of nitrate nitrogen in ordinary chernozem of the forest-steppe zone of the Krasnoyarsk Territory. The studies were carried out in 2017-2019 years in three-field grain-steam and 8 grain-grass crop rotations. Melilot and sainfoin were cultivated neat and under the cover of barley, incl. with seed treatment with Rizotorfin inoculant. Winter rye was sown in 2018 in a field of clean fallow in a grain-fallow crop rotation and after mowing the second cut of perennial grasses of the 2nd year of use in grain-grass crop rotations with a stubble seeder SZS-2.1 without preliminary tillage.It has been established that a high supply of nitrate nitrogen is characteristic of a steam field in a 0-20 cm layer of chernozem (19 mg/kg). The average supply of chernozem with nitrate nitrogen was formed by coverless crops of sweet clover and sainfoin and cover crops of sweet clover (9-10 mg/kg). In the crops of winter rye, according to various predecessors, an intensive consumption of mineral nitrogen by plants and a very low supply of soil with nitrate nitrogen (2-5 mg/kg) were noted. Grain-grass crop rotation with the cultivation of winter rye on binary and pure crops of sweet clover created the best conditions for the accumulation of nitrate nitrogen in the 0-40 cm layer of chernozem (6-8 mg/kg). The treatment of sweet clover and sainfoin seeds with the inoculant Rizotorfin determined a more intensive absorption of nitrate nitrogen from the soil and a low supply of nitrate nitrogen to the soil (4-6 mg/kg) in the crop rotation.

Reciprocating subsurface-flow constructed wetlands: a microcosm treatability study.

Two batch-loaded microcosm treatability studies of eight days' duration (192 hours) were conducted concurrently from July 26 through August 3 in an environmentally controlled greenhouse at the Tennessee Valley Authority's (TVA) Constructed Wetlands Research Facility in Muscle Shoals, Alabama, USA. These, the first of five treatability studies, were conducted in batch-loaded wetland microcosms, with and without reciprocation. Reciprocation refers to the process of filling and draining paired wetland cells on a recurrent and timed basis to facilitate passive aeration of fixed microbial biofilms during the drain phase and oxygen depletion during the fill phase. The study was designed to simultaneously evaluate the influence of three treatment parameters with respect to removal dynamics of chemical oxygen demand (COD), total ammonia-nitrogen (TAN), nitrate-nitrogen, and orthophosphorus. The treatment parameters evaluated included four COD concentrations, two reciprocation cycle times, and the presence or absence of reed canary grass (Phalaris arundinacea), a plant with an anoxic rootzone. Temperature, pH, dissolved oxygen, electrical conductivity, redox potential, and evapotranspiration were also monitored. Results showed that treatments with reciprocation vs. no reciprocation provided significantly enhanced aerobic and anoxic treatment of wastewater and improved removal of COD and ammonium, irrespective of initial COD concentrations or planted vs. not planted with P. arundinacea. Treatments with P. arundinacea had less accumulation of nitrate nitrogen; less than 0.4 mg/L., while reciprocating treatments without P. arundinacea accumulated from 15-26 mg/L nitrate nitrogen over the 192-hour treatment period.

Perbandingan Sistem Resirkulasi dan Air Mengalir Untuk Pembesaran Lobster Pasir (Panulirus Homarus): Kajian Dinamika Kualitas Air

Aquaculture with the Recirculation Aquaculture System (RAS) is a unique engineered ecosystem that minimizes environmental disturbances by reducing the discharge of nutrient pollution through reuse of water used in fish farming. This activity was conducted at LP2IL Serang field test facility starting in June-November 2020. In this test, the RAS system used for growing of sand lobster uses the stages of purification: sedimentation, physical filtration, biological filtration, water disinfection with UV irradiation, removal of CO2, clean water reservoirs and sand lobster rearing tanks. Water quality parameters tested: a) physics: DO, pH, temperature and salinity are measured every day; b) chemistry: ammonia (TAN and UIA), nitrite, nitrate and phosphate are measured every two weeks. If from the UIA value calculation, the value is above the quality standard (&gt; 0.05 mg / L) then added molasses (26.02% organic C) with a concentration of 64 gr / gr TAN; c) microbiology: total bacteria and Vibrio sp. counting. From the results of this study it is known that RAS can maintain stable water quality for a relatively long time. High availability of organic matter (from leftover feed, feces and addition of molasses) can promote the growth of nitrifying bacteria. The "maturation" of the nitrifying bacteria in the biofilter compartment takes about 6 weeks. These bacteria are able to reduce levels of ammonium nitrogen, where the accumulation of nitrate nitrogen (NO3-) which is produced from the overhaul of nitrite nitrogen (NO2-) by nitrifying bacteria, is a signal that the maturation process of nitrifying bacteria has been achieved. The nitrification process consumes alkalis, hence lowers the pH value in the water, besides it also consumes a large amount of oxygen. The low number of bacteria and vibrio in the RAS system was affected by the use of a UV-sterilizer with a wavelength of 254 nm.

Impact of mineral fertilizers on winter wheat quality using No-Till technology

The paper presents the study of the influence of ammophos, potassium magnesia and ammonium nitrate on the content of protein, gluten and grain unit of winter wheat using No-Till technology in the edaphoclimatic conditions of the southern zone of Rostov Region. It was shown that the application of mineral fertilizers to the surface soil layer during winter wheat cultivation using No-Till technology improves the grain quality. The highest grain quality parameters (protein content – 13.4% and gluten content – 25.3%, grain unit – 780.0 g/l) were obtained when ammophos and potassium magnesia were jointly added prior to sowing at a depth of 10 cm with double dressing of ammonium nitrate in the tillering and booting phases. High direct dependence of protein content in winter wheat grain on the accumulation of nitrate nitrogen in soil in the booting phase was revealed in all test layers: 0–10 (r = 0.85), 10–20 (r = 0.72), 0–30 cm (r = 0.76). The gluten content in the grain and its grain unit significantly depended on the mobility of phosphorus in the surface soil layer – 0–10 cm (r = 0.66 and 0.52, respectively). Along with the quality improvement of winter wheat grain, the rational use of mineral fertilizers in the No-Till system increases its yield. There is a direct positive relationship between grain protein content and winter wheat yield (r = 0.93).

Morpho-physiological traits, antioxidant capacity and nutrient accumulation in hemp (Cannabis sativa L.) under varying levels of nitrogen nutrition

Optimization of nitrogen fertilizer application is an important means of improving hemp (Cannabis sativa L.) production and economic benefits with minimum environmental loss. The method of fertilization with hydroponic could precisely control the amount of nitrogen applied, to understand how nitrogen application can affect the growth and physiology of industrial hemp. A hydroponic experiment was conducted in 2017 to investigate the effects of different nitrogen treatments (0.30, 0.75, 1.50 and 12.00 mmol/L) on different regions and types, cultivars of hemp (“Wanma 1(WM1)”, “Bamahuoma (BM)’, “Ynuma 5 (YM5)” and “Yunma 7 (YM7)”). The main objective was to determine the effectiveness of nitrogen fertilizer application for improvement of the morpho-physiological traits, antioxidant capacity and nutrient accumulation of industrial hemp. In general, increasing N application rate positively impacts hemp total dry biomass, plant height and stem diameter. Total dry weight, stem diameter and plant height increased by 26.16%-238.94%, 11.43%-34.09% and 4.51%-54.73%, respectively, with the application of 1.50 mmol/L when comparing with the low N rate (0.30 mmol/L). Nitrogen deficiency leads to cell membrane lipid peroxidation (MDA) and increases in superoxide dismutase (SOD) activity. The activity of nitrate reductase (NR) in hemp leaves and the accumulation of nitrate nitrogen are related not only to the nitrogen supply but also to the form of nitrogen. In addition, increasing nitrogen supply has a significantly negative effect on the utilization efficiency of nitrogen and potassium, but positively on the phosphorus utilization efficiency. Nitrogen supply and cultivar proved to be relevant to the growth, physiology and nutrient accumulation in hemp under hydroponic conditions. Increasing nitrogen supply within a reasonable range is beneficial to hemp, whereas excessive nitrogen supply has an inhibitory effect, and the nutrient utilization efficiency significantly reduces.

Ecological and agrochemical features of chemical agents use on soils contaminated with cadmium and copper in the link of vegetable rotation

The article presents mobility coefficients of cadmium and copper, biological absorption coefficients of toxic metals by the main products of potatoes, beetroot and beans, depending on the chemicalization agents used on black soil with a typical heavy loamy granulometric composition. The introduction of lime, the combined application of lime and manure have a positive effect on reducing the coefficient of cadmium mobility. The high content of cadmium and copper in the soil does not have a negative effect on the synthesis of basic organic substances in vegetable products (starch, sugar, protein). The accumulation of nitrates in vegetable products occurs as a result of the mineral and organic fertilizers application; heavy metals do not have a significant effect on the accumulation of nitrate nitrogen during the cultivation of vegetable crops. The coefficient of biological absorption is influenced not only by lime, manure, mineral fertilizers, but also by the physiological characteristics of the crops themselves, which need toxic elements as micro and ultramicroelements for nutrition and synthesis of organic substances. The results of studies on crops of beetroot show that the application of lime, manure and the combined application of lime and manure reduce the intake of cadmium, copper, lead and zinc in root crops and tops of beetroot. A double dose of mineral fertilizers reduces the intake of copper and lead, but insignificantly, and does not have a positive effect on reducing the accumulation of cadmium and zinc. On soils contaminated with heavy metals (Cd, Cu), according to the value of biological absorption coefficient of the studied crops, heavy metals are distributed as follows: when growing potatoes - Cd> Cu; when cultivating table beet - Cu> Cd; when growing beans - Cu> Cd.

Optimization of irrigation amount and fertilization rate of drip-fertigated potato based on Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation methods

As a cash crop, potato plays an important role in the economic development and ensuring food security. Reasonable management of irrigation and fertilization can promote the uptake of water and nutrients by potato, thereby improving the tuber yield and quality, and reducing fertilizer residues in the soil. A four-year field experiment was carried out to explore the effects of different irrigation amounts and fertilization rates on potato yield, economic benefit, tuber quality, water productivity (WP) and fertilizer use efficiency (FUE), and soil nutrient residues during 2016–2019. Multi-objective optimization of irrigation amount and fertilization rate was conducted based on data in 2018 and 2019 using the Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation methods. In 2016 and 2017, three irrigation levels (W1, 60% ETC; W2, 80% ETC and W3, 100% ETC) and three fertilization (N-P-K) rates (F1, 100–17.5–124.5 kg/ha; F2, 150–26.2–186.7 kg/ha and F3, 200–34.9–248.9 kg/ha) were applied. The highest tuber yield was obtained under F3 in 2016 and 2017. Two fertilization rates (F0, 0 kg/ha and F4, 250–43.7–311.2 kg/ha) were further considered in 2018 and 2019. Results showed that the highest tuber yield, net income, WP, dry matter and the residues accumulation of nitrate nitrogen, available phosphorus, and available potassium were obtained under F4 in 2018 and 2019. However, the differences in tuber yield, net income and WP between F3 and F4 were not significant under W3. Deficit irrigation reduced tuber yield, ET, net income, shoot dry matter, tuber dry matter, LAI, relative chlorophyll content, starch and vitamin C content and FUE, and increased the residues of nutrient in the soil and reducing sugar content. Besides, W1 showed the highest irrigation water productivity, but the starch and vitamin C content of W3F2 were largest. The highest FUE was obtained under W3F3 (56.33% in 2018 and 53.33% in 2019). Increasing fertilization rate decreased the fertilizer partial factor productivity and sink/source. Based on the economic benefit, tuber quality, WP and FUE and soil environmental benefit, the multi-objective optimization was evaluated by the Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation methods. When the irrigation amount was 100% ETC (W3) and the fertilization rate (N-P-K) was 200–34.9–248.9 kg/ha (F3), the multi-objective optimization was obtained. The results can provide a theoretical basis for the optimization of water and fertilizer regimes of potato in northern China and other regions with similar environments.

Influence of microbial preparations on biomorphological indicators of tulip (&lt;i&gt;Tulipa&lt;/i&gt; L.) ‘Anna Krasavitsa’ and soil fertility under steppe Crimea conditions

The data on the study of the effect of treatment of tulip bulbs of the Anna Krasavitsa cultivar before planting with microbial preparations (MP) Aurill and the Complex of microbial preparations (CMP) on the growth, state, ability for vegetative propagation of tulips, as well as the fertility and biological activity of the tulip rhizosphere in Crimea have been presented in the article. The studies were carried out in 2017-2019 in a small-plot field experiment on the tulip collection site of the NBG-NSC (v. Novy Sad, Simferopol district of the Republic of the Crimea) on the southern carbonate chernozem. Tulip bulbs were treated with MP working suspensions before planting with a dose of the preparation equal to 2 % of the bulb mass. The control - treatment with tap water. The study, collection and processing of the obtained data on the state of plants, fertility and biological activity of the soil was carried out by generally accepted methods. As a result of the studies was found that MPs increased the coefficient of vegetative propagation of bulbs, the mass of the nest and replacement bulb by 6-23 %, at the same time, a positive effect of CMP on an increase in the mass of large bulbs was revealed in the axils of the storage scales. The features of the influence of the treatment of tulip bulbs ‘Anna Krasavitsa’ with Aurill and CMP preparations on the morphometric characteristics of the plant have been revealed: the height and size of the flower and the lower leaf were increased. A positive effect of the preparations on soil fertility under tulips was shown: CMP promoted an increase in the organic matter content in the soil by 0.19 %, Aurill - the accumulation of nitrate nitrogen and exchangeable potassium in the rhizosphere of a tulip, and increasing its biological activity. The use of MP increased the number of ammonifying and amylolytic bacterial groups in the rhizosphere of the tulip; to a greater extent, Aurill, CMP increased the number of phosphate-mobilizing (by 58 %), as well as oligotrophic and cellulolytic bacteria by 8 and 78 % respectively. Aurill suppressed the number of micromycetes by 48 %.

灌溉定额和施氮量对机采棉田水分运移及硝态氮残留的影响

<p id="C3">The shortage of water resources and the excessive investment of fertilizer are the bottlenecks that restrict the sustainable and healthy development of agriculture and force farmers to develop and adopt sustainable production technologies. The mechanism of water movement and the residual behavior of nitrogen fertilizer are important scientific issues to evaluate the level of agricultural water and fertilizer management in arid areas. Improving the water and nitrogen utilization efficiency was an important way to reduce environmental pollution. An experiment was conducted using a split plot design with the main area for total irrigation of 2250 (W1, non-sufficient drip irrigation), 3450 (W2, conventional drip irrigation), 4650 m ³ hm ^-2 (W3, saturated drip irrigation), and the deputy area of nitrogen (pure N) including 0 (N1, no fertilizer), 300 (N2, conventional fertilization), 600 kg hm ^-2 (N3, excess fertilization) in arid area of northwest China cotton region from 2018 to 2019. The effects of irrigation and nitrogen levels on water distribution, nitrate nitrogen residue, seed cotton, irrigation water, and N fertilizer productive efficiency were evaluated. The results revealed that irrigation and coupling effects of irrigation and nitrogen levels were the influencing factors on seed cotton and water utilization efficiency, among which irrigation was the main effect. Two-year average values demonstrated that the irrigation was W1, nitrogen fertilization amount increased from N1 to N3, and the average soil moisture content of 0-80 cm during the whole growth period increased first and then decreased. Compared with N1 fertilization application, seed cotton yield was 13.8% and 7.6% higher and irrigation water productive efficiency were 13.6% and 6.8% higher under N2 and N3 fertilization application, respectively. When the irrigation was W2 and W3, the nitrogen fertilization amount increased from N1 to N3, and there was no significant difference in the average soil moisture content of 0-80 cm during the whole growth period. Compared with N1 fertilization application, seed cotton yield was 11.4% and 11.5% higher and irrigation water productive efficiency were 13.6% and 6.8% higher under N2 and N3 fertilization application, respectively. With the increase of irrigation, the total average value of 0-80 cm during the whole growth period gradually increased. Irrigation was the main effect on soil nitrate nitrogen accumulation in the main distribution area of 0-40 cm roots, and coupling effects of irrigation and nitrogen levels was the main factor leading to nitrate nitrogen leaching. When the irrigation was W1, nitrate nitrogen accumulated in the 0-40 cm with the increase of nitrogen. And when the irrigation was W3, nitrate nitrogen accumulated in the 40-60 cm with the increase of nitrogen. In conclusion, if the irrigation was higher than 3450 m ³ hm ^-2 and nitrogen was higher than 300 kg hm ^-2, the continued increase of water and nitrogen input failed to increase production, which might result in resource waste and potential pollution to the environment. Therefore, we suggest that water and nitrogen optimization strategies can improve resource utilization efficiency, reduce water and fertilizer input, and healthy development of agriculture.

Nutritional Regime of the Soil and Growth Activity of the Apple Tree Root System in Orchards with Legume-Cereal Grass Intercropping

This work aims to study the influence of legume-cereal grasses in the inter-row spacings of the garden on the content of nutrients in the soil and the growth of apple tree roots. The amount of nitrate nitrogen was in direct proportion to the ratio of the legume component in the phytocenosis. The nitrogen content in the control option was the smallest: 19.7 mg/kg in the soil layer of 0-30 cm and 13.4 mg/kg in the layer of 30-60 cm. In the case of natural grassing-down between rows, cereal forbs prevailed. The largest amount of nitrate nitrogen was achieved when sowing the red clover and timothy grass in a ratio of 7:3. The accumulation of nitrate nitrogen is due to the activity of nodule bacteria on the roots of red clover. The accumulation of mobile phosphorus and exchangeable potassium depends on the amount of mowed mass in the inter-row spacings of the garden. The lowest content of mobile phosphorus was detected for natural grassing. In the control option, its amount was 118 mg/kg. In the 0-30 cm soil layer, the content of mobile phosphorus was 127.4-142.6 mg/kg depending on the ratio of legume-cereal grasses, and it amounted to 95.1-103.2 mg/kg in the 30-60 cm layer. For the ratio of red clover and timothy grass 3:7, the highest phosphorus content was detected. The intercropping of the garden with a legume-cereal herbal mixture also contributed to a greater accumulation of exchangeable potassium in the soil relative to natural grassing-down - 122.3-134.9 mg/kg. The optimal ratio of legume-cereal component was 3:7. A higher growth activity of the roots of the apple tree was noted in the option with sodding with a mixture of red clover and timothy grass in a ratio of 7:3.