Mineral Nitrogen Fertilizer Research Articles

Effect of different nitrogen sources combination with bio-fertilizers on yield and chemical composition of canola and sesame crop

Two field experiments were carried out during winter season (2016/2017) and summer season (2017) an clay soil to evaluate the effects of bio-fertilizers (Azospirillum and Azotobacter) and different nitrogen fertilizer sources i.e., ammonium nitrate (AN), slow release nitrogen fertilizer ureaform aldehyde (SRF) and organic fertilizer (OF) at rate of 100% in absence of bio fertilizer and at rate of 75% nitrogen from recommend dose for both canola as winter season crop and sesame as summer season crop on the growth, chemical composition as well as concentration and yields of protein and oil in both canola and sesame crops. The results of the analyzes showed that the use of bio-fertilizer with mineral nitrogen fertilizer increased plant growth rates, (number of pods/plant, height plant, weight of 1000 Seeds (g), number of seeds/ capsule, seeds and straw yields, biological yield as well as the harvest index of both canola and sesame plants compared with mineral fertilizer AN and SRF alone. The highest values of concentration and uptake of N, P and K in both straw and seeds were obtained by application of nitrogen fertilizer with bio-fertilizer. Interaction between nitrogen fertilizer and bio-fertilizer achieved suitable protein and oil percent and could be improve canola and sesame seeds quality. On the other hand, some soil chemical properties (EC, pH and O.M) were enhanced due to application of mineral nitrogen with bio-fertilizer.

Influence of mineral fertilizers and seeding rates on the yield and quality of spring wheat grain

The article presents the results of field research conducted in 2018-2019 on leached Chernozem of the Volga forest-steppe. The objects of research are varieties of spring wheat-Tulaykovskaya 10, Yoldyz and Tulaykovskaya 108. At different seeding rates of 5.0 and 5.5 million germinating seeds per ha, the effect of mineral fertilizers on 1 ha was studied. They were represented by a complete mineral fertilizer (azofoska) and fertilizing with a mineral nitrogen fertilizer in the tillering phase at doses of 30, 60 and 90 kg of AD/ha against this background. Analysis of the yield of spring wheat varieties indicates that the harvest of grain variety Yoldyz in variants with a seeding rate of 5.5 million germinating seeds per ha against the background of the application of ammonium nitrate at a dose of 60 kg of DA (2.52 t/ha) was superior to other varieties Tulaykovskaya 10 and Tulaykovskaya 108 (2.51 and 2.46 t/ha). The maximum increase in seed productivity when adding ammonium nitrate in the tillage phase of the crop was in Tulaykovskaya 10 variety (0.34 t/ha), the lowest in the Yoldyz variety (0.06 t/ha) compared to the variant with amofoska application in the pre-sowing cultivation. When increasing the doses of nitrogen fertilizers there was an increase in the water content of all the studied varieties by 1-3 PCs. While increasing the seeding rate from 5.0 to 5.5 million germinating seeds per 1 ha the number of grains in the ear changed on average for varieties by 1-2 PCs. Of all the studied varieties, the largest mass of 1,000 grains was in the Yoldyz variety (40.56 g) after azofoska application in the presowing cultivation + N60 during tillering at a seeding rate of 5.0 million germinating seeds per 1 ha, the smallest in the Tulaykovskaya 108 variety (37.87 g) after azofoska application at a dose of 0.15 t/ha at a seeding rate of 5.0 million germinating seeds per 1 ha.

Statistical Analysis versus the M5P Machine Learning Algorithm to Analyze the Yield of Winter Wheat in a Long-Term Fertilizer Experiment

To compare how different analytical methods explain crop yields from a long-term field experiment (LTFE), we analyzed the grain yield of winter wheat (WW) under different fertilizer applications in Müncheberg, Germany. An analysis of variance (ANOVA), linear mixed-effects model (LMM), and MP5 regression tree model were used to evaluate the grain yield response. All the methods identified fertilizer application and environmental factors as the main variables that explained 80% of the variance in grain yields. Mineral nitrogen fertilizer (NF) application was the major factor that influenced the grain yield in all methods. Farmyard manure slightly influenced the grain yield with no NF application in the ANOVA and M5P regression tree. While sources of environmental factors were unmeasured in the ANOVA test, they were quantified in detail in the LMM and M5P model. The LMM and M5P model identified the cumulative number of freezing days in December as the main climate-based determinant of the grain yield variation. Additionally, the temperature in October, the cumulative number of freezing days in February, the yield of the preceding crop, and the total nitrogen in the soil were determinants of the grain yield in both models. Apart from the common determinants that appeared in both models, the LMM additionally showed precipitation in June and the cumulative number of days in July with temperatures above 30 °C, while the M5P model showed soil organic carbon as an influencing factor of the grain yield. The ANOVA results provide only the main factors affecting the WW yield. The LMM had a better predictive performance compared to the M5P, with smaller root mean square and mean absolute errors. However, they were richer regressors than the ANOVA. The M5P model presented an intuitive visualization of important variables and their critical thresholds, and revealed other variables that were not captured by the LMM model. Hence, the use of different methods can strengthen the statement of the analysis, and thus, the co-use of the LMM and M5P model should be considered, especially in large databases involving multiple variables.

Efficiency of Mineral Nitrogen Fertilization in Winter Wheat under Pannonian Climate Conditions

Improvements in nitrogen (N) use efficiency in crop production are important for addressing the triple challenges of food security, environmental degradation and climate change. The three fertilizers, calcium ammonium nitrate (CAN), urea (Urea) and stabilized urea (Ureastab), were applied at a rate of 160 kg N ha−1 with two or three splits to winter wheat (Triticum aestivum L.) in the Pannonian climate region of eastern Austria. On average, over all fertilization treatments, the grain yield (GY) increased by about a quarter and the grain N concentration (GNC) doubled compared to the control without fertilization. Consequently, the grain N yield (NYGRAIN) was increased with N fertilization by 154%. The GY increased due to a higher grain density with no differences between N fertilizers but with a tendency of a higher grain yield with three compared to two splits. Three splits also slightly increased the GNC and consequently the NYGRAIN of CAN and Ureastab in one year. The removal of N fertilizer with the NYGRAIN (N surplus) was higher than the amount of applied fertilizer. Fertilization decreased the N use efficiency (NUE), the N uptake efficiency (NUpE) and the N utilization efficiency (NUtE) but increased the soil mineral nitrate (NO3-N) at harvest and the apparent N loss (ANL). Three compared to two applications resulted in a higher NO3-N at harvest but also a lower N surplus due to partly higher NYGRAIN. Consequently, the ANL was lower with three compared to two splits. Also, the NUpE and the apparent N recovery efficiency (ANRE) were higher with three splits. The best N treatment regarding highest above-ground biomass yield with lowest N surplus, N balance and ANL was the three-split treatment (50 CAN, 50 CAN, 60 liquid urea ammonium nitrate). Three splits can, under semi-arid conditions, be beneficial when aiming high-quality wheat for bread-making and also for reducing the N loss. Whereas, two splits are recommended when aiming only at high GY, e.g., for ethanol-wheat production.

The Influence of Different Fertilization Strategies on the Grain Yield of Field Peas (Pisum sativum L.) under Conventional and Conservation Tillage

Weather, tillage, and fertilization are the major factors affecting the grain yield of field peas (Pisum sativum L.). However, the impact of tillage and fertilization on yield is not well understood. Therefore, this experiment was initiated in 1999. In this manuscript, we report the data recorded during the period of 2011–2015 to quantify the impacts on yield. Field peas were planted in seedbeds prepared through conventional tillage (CT)—moldboard ploughing to the depth of 0.22 m; and minimum tillage (MT)—disking to the depth of 0.12 m. The crop received three fertilization treatments, including zero fertilization (control); nitrogen, phosphorus and potassium (NPK) mineral fertilization treatment; and NPK mineral fertilization plus the incorporation of pre-crop biomass. Five years’ average data indicated the highest yield on fertilized treatments (2.85–2.98 t ha−1 vs. 2.66 t ha−1) regardless of the tillage. When comparing the yield of fertilized treatments, the yield under CT (2.98 t ha−1) was significantly higher than that of MT (2.85 t ha−1). However, on non-fertilized treatments (less fertile plots), a higher yield was recorded under MT (2.71 t ha−1) compared with CT (2.40 t ha−1). Overall, the results of this study suggest that fertilizer application together with incorporation of the above-ground biomass of the previous crop may help sustain pea grain yield.

Production of Soybean Plants for Hydroponic Cultivation from Seedling Cuttings in a Medium Containing Rhizobium Inoculum Depending on Various Concentrations of Nutrient Solution and Different Nitrogen Sources

Abstract There has been an increasing interest in soybean cultivation in hydroponic systems. Because soybean plants can utilize nitrogen derived from biological N2 fixation, the use of Rhizobium inoculated plants may eliminate or decrease the need for mineral nitrogen fertilization in hydroponic systems. Thus, the objective of this study was to establish effective methods for making inoculated soybean transplants for a substrate-based hydroponic system. Inoculated plants were effectively produced by rooting seedling stem cuttings in a medium containing a Rhizobium inoculant. We also investigated the effects of different nitrogen forms and sub-irrigated nutrient solution concentrations on the growth and root nodule formation of the inoculated plants. The application of a nitrogen-free nutrient solution had minimal positive effects on the growth and nodulation of the inoculated plants. Ammonium-fed plants lacked root nodules regardless of the ammonium concentration. Furthermore, a 50% nutrient solution combining with nitrate or urea as the nitrogen source did not promote root nodulation. Therefore, inoculated plants should be subirrigated with an approximately 25% nutrient solution supplemented with nitrate or urea to induce early growth and nodulation prior to transplantation.

Enhanced root carbon allocation through organic farming is restricted to topsoils

Soils store significant amounts of carbon (C) and thus can play a critical role for mitigating climate change. Crop roots represent the main C source in agricultural soils and are particularly important for long-term C storage in agroecosystems. To evaluate the potential of different farming systems to contribute to soil C sequestration and thus climate change mitigation, it is of great importance to gain a better understanding of the factors influencing root C allocation and distribution. So far, it is still unclear how root C allocation varies among farming systems and whether the choice of management practices can help to enhance root C inputs. In this study, we compared root C allocation in three main arable farming systems, namely organic, no-till, and conventional farming. We assessed root biomass, vertical root distribution to 0.75 m soil depth, and root-shoot ratios in 24 winter wheat fields. We further evaluated the relative importance of the farming system compared to site conditions and quantified the contribution of individual management practices and pedoclimatic drivers. Farming system explained one third of the variation in topsoil root biomass and root-shoot ratios, both being strongly positively related to weed biomass and soil organic C content and negatively to mineral nitrogen fertilization intensity. Root C allocation was significantly higher in organic farming as illustrated by an increase in root biomass (+40%) and root-shoot ratios (+60%) compared to conventional farming. By contrast, the overall impact of no-till was low. The importance of pedoclimatic conditions increased substantially with soil depth and deep root biomass was largely controlled by precipitation and soil texture, while the impact of management was close to zero. Our findings highlight the potential of organic farming in promoting root C inputs to topsoils and thereby contributing to soil organic matter build-up and improved soil quality in agroecosystems.

Productivity of corn for grain at different doses of fertilizers and methods of tillage

The development and implementation of the most optimal agricultural technologies for cultivating crops will allow you to maximize the potential of plants and get high productivity with good quality products. Among the variety of organic fertilizers currently used, a special place is occupied by poultry manure with a high content of nutrients found in the compounds assimilated by plants. In terms of the South-Western part of Central Black earth region, were studied combined effect of methods of primary tillage, doses of poultry manure and compost, combines them in making nitrogen fertilizers and mineral fertilizers on soil agrochemical parameters and grain productivity of corn. The productivity when plowing was 5,79 t/ha in the control variant, with beardless plowing – 4,91 t/ha and with no deep tillage – 4,8 t/ha. Poultry manure and compost (20 t/ha) in its pure form has increased the productivity by 1,02 and 0,87 t/ha when tilling, by 0,82 and 0,89 t/ha when beardless plowing by 0,78 and 0,83 t/ha when no deep tillage relative to control. Additional input in these variants of nitrogen fertilizer led to increase of productivity of corn to 6,99 and of 7,23 t/ha when tilling, which was higher than poultry manure (20 t/ha) and bird compost (20 t/ha) by 0,18 and 0,57 t/ha, when beardless plowing to 5,79 and of 6,37 t/ha. In order to cultivate corn for grain in the South-Western part of the Central Black earth region, it is necessary to plow to a depth of 22-25 cm as the main soil tillage. As the main fertilizer for obtaining stable productivity of corn for grain with the preservation of soil fertility at a high level of profitability, it is necessary to apply poultry manure at a dose of 20 t/ha. In order to achieve higher productivity of corn, we recommend the joint application of organic and mineral fertilizers in the dosage of poultry manure (20 t/ha + N 60) and poultry compost (20 t/ha + N 60).

Characterising the effect of crop species and fertilisation treatment on root fungal communities

Information about the root mycobiome may improve the overall quality of the plants and contribute to a valuable strategy to enhance sustainable agriculture. Therefore, we assessed differences in fungal community diversity and composition in the roots of potato, wheat and barley grown under mineral nitrogen fertilisation at five rates, with and without farmyard manure amendment. The same factorial combination of treatments has been used since 1989. Species richness and diversity, as well as community composition, of different fungal guilds were characterised using Illumina MiSeq sequencing of the ITS2 region. Crop species was the main factor determining overall fungal richness and diversity, with wheat showing the highest, and potato the lowest, richness and diversity. Pathogen diversity indices were highest in wheat plots amended with farmyard manure, whereas the lowest values were observed for potato roots. Fertilisation treatments and the interaction between crop species and fertilisation had the strongest impact on arbuscular mycorrhiza and saprotroph diversity. Crop species also determined the composition of the overall fungal community and that of fungal guilds, whereas fertilisation treatment had only a minor effect. This study highlights crop species as the main driver in shaping root fungal diversity and composition under the same environmental conditions.

Long-Term Fertilization Affects Soil Microbiota, Improves Yield and Benefits Soil

Fertilization of soil is needed to fulfill the growing demand for livestock feed and human food requirements. However, fertilization has short and long-term impacts on the soil microbiota. These, in turn, may influence plant viability and growth. We investigated the soil microbiota of a 27-year field trial, focusing on the influences of mineral nitrogen (N) fertilization, different composts and combinations of compost plus mineral N as soil amendments. Two N rates (0 and 80 kg per ha) and four different composts (urban organic waste compost (OWC) green waste compost (GC), farmyard manure (MC) compost and sewage sludge compost (SSC)) were used. Soil samples for this study were taken in 2018 after the growing season of maize. In addition to maize yield, the effects on soil physicochemical properties and the soil microbiota were analyzed. There was a trend for increased maize yields for all fertilizers; however, only the application of GC and SSC in combination with mineral N fertilizer showed significant effects. The different organic amendments influenced physicochemical soil properties. Phosphorus concentrations were three times higher in plots receiving SSC (≈312 mg kg−1) and SSC + N (≈297 mg kg−1) than control (≈89 mg kg−1) or mineral N fertilizer (≈97 mg kg−1) alone. Magnesium concentrations in plots treated with SSC (≈74 mg kg−1) were lower compared to soils treated with GC and MC, respectively (≈135 mg kg−1 and 126 mg kg−1). Bacteria exceeded the fungal community in terms of both richness and diversity. While the bacterial community composition differed significantly among the treatments, the fungal community composition was rather unaffected. Our conclusion is that composts produced from various substrates serve as valuable nutrient sources for plants and can partially substitute mineral N. In addition, composts increased soil microbial biomass and modulated the composition of the soil’s microbial community.

Dynamics of alfalfa leaf area depending on nitrogen feeding type

The results of field studies for 2017-2019 of dynamics of assimilation surface of alfalfa crops depending on the type of nitrogen nutrition and symbiotic activity of crops are given. Tests with Medicago varia Mart. were carried out in environmental conditions of the pre-mountain zone of RNO-Alania (540 meters above sea level) on the black earth leached with close occurrence of pebbles. Mineral and symbiotrophic types of nitrogen nutrition of alfalfa plants were compared. The experience scheme included options: control - natural soil fertility; In-1800 - treatment of seeds with inoculum of strains of nitrogen-fixing bacteria selected in high mountain conditions (1800 m above sea level); Strain 425a - inoculation of seeds with industrial strain rhizotorphin (strain 425a); N30 - starting nitrogen dose; N30+In is the joint use of highland strains of bacteria and starting doses of nitrogen. Seeds were treated with the strains studied before sowing. Mineral nitrogen fertilizers were introduced annually early in spring in the form of starting doses. It has been established that the minimum areas of leaves on all variants are observed in the first year of life, in the second year of use of crops the maximum assimilation surface is formed in plants, in the third year - indicators gradually decrease. Every year, the maximum assimilation surface is formed by perennial leguminous herbs to the budding stage - the beginning of flowering (bevel has fallen). The dynamics of leaf surface build-up is directly proportional to the activity of symbiotic relationships with rhizobias. In variants with the highest symbiotic activity (In-1800 and N30+In) the area of leaves reaches maximum values and exceeds 40 thousand m ?/ha in certain years.

Identifying N fertilizer management strategies to reduce ammonia volatilization: Towards a site-specific approach

Concerns about ammonia (NH3) losses from nitrogen (N) mineral fertilizers have forced policymakers to set emission reduction commitments across Europe. Although best available techniques (BATs) have been recommended, large uncertainties still exist due to poorly targeted site-specific approaches that might compromise their effectiveness. Here we proposed and tested a conceptual framework designed to identify most effective BATs that reduce NH3 at the site-specific level. The study was conducted in the Veneto region, northeast Italy. After the mapping of NH3 emission potential areas, BATs and business-as-usual N fertilization scenarios were assessed using a modified version of the DNDC agroecosystem model and compared with urea broadcast distribution under different pedo-climatic conditions. The most promising practices were further tested in a field experiment using a wind tunnel combined with a FTIR gas analyzer. Results showed that closed-slot injection reduced NH3 emissions with any type of mineral or organic fertilizers. Injected application, with ammonium nitrate or organic fertilizers, reduced NH3 loss in maize by 75% and 96%, respectively, and in winter wheat by 87% and 98%, compared to surface broadcast. Injection was the most promising technology to support, being already available to farmers. However, some increase in nitrate leaching was observed, mostly in case of winter wheat (+24% for AN injection; +89% for organic fertilizers). By contrast, urea incorporation with hoeing, the most common technique used by farmers in spring crops, did not show satisfactory results, because the partial burial of urea caused strong NH3 emissions that were even higher compared to surface broadcast. Recommended NH3 reduction techniques should be tailored to local pedo-climatic and management conditions, and evaluated, in a holistic approach, considering all N fluxes in the environment.

Mitigation of CO2, CH4 and N2O from Acidic Clayey Soil Amended with Fertilizer Pellets Based on Alkaline Organic Residues

Alkaline organic residues, such as wood ash (WA), deinking paper sludge (DPS), and mixed paper sludge (MPS) could have a significant potential for mitigating greenhouse gases (GHG) when they are used for land application. The DPS was mixed and then granulated with MPS, WA and/or composted DPS to form pellets. A 56-d incubation study was carried out to investigate the effect of alkaline organic residue pellets on: (1) the biological and chemical properties of acidic clayey soil; (2) on carbon dioxide (CO2), on methane (CH4), and nitrous oxide (N2O) soil emissions. The experimental design included eight different treatments: unfertilized control (Control), fertilized control with mineral nitrogen (controlF), and six pelleted alkaline organic residue amendments (T1–T6) combined with mineral nitrogen fertilizer. The six amendments were: (T1) 100% DPS; (T2) 100% composted [50% poultry manure and 50% T1]; (T3) 50%WA + 50% T1; (T4) 50% WA + 50% T2; (T5) 50%T2 + 30%WA + 20% MPS; (T6) 50% T1 + 30%WA + 20% MPS. The results showed that alkaline residues significantly increased soil pH, the concentration of water-extractable organic carbon, and water-extractable nitrogen. Alkaline treatments had a positive effect on soil microbial activity. The highest mitigation efficiency of cumulative CO2 was obtained with T4, which released 10% less CO2 than other treatments. No significant effect on cumulative CH4 emissions was observed. Total cumulative N2O emissions were reduced by 37% with T5. Our study also showed that organic pellets based on alkaline residues improved the soil properties and can play a role in the mitigation of GHG in acidic clayey soil. Therefore, the co-application of alkaline organic residue pellets with chemical fertilizer might be considered as a sustainable approach in agriculture.

Complementary Effect of Biofertilizer with Mineral Nitrogen Fertilizer on Canola Plant Productivity التأثیر المکمل للسماد الحیوى مع التسمید النیتروجینى المعدنى على إنتاجیة نبات الکانولا

Biofertilizers are recently used on a large scale to reduce chemical fertilizers and their pollutant effect on soils and water. In this work, a pot experiment was carried out to evaluate the effect of Azotobacter chroococcum, Azospirillum lipoferum and Klebsiella oxytoca with different levels of nitrogenous fertilizer on the growth and yield of canola (Brassica napus L.) and microbial population in the soil during the winter season, 2018. Results reveal that used bacterial species as biofertilizers have a great effect on morphological and yield traits of canola plants, where the plants treated with Azotobacter, Azopirillum and Klebsiella were characterized by increases in plant heights, plant weights as well as numbers of branches and pods. Also, Azotobacter and Azospirillum increased nitrogen, whereas Klebsiella oxytoca increased phosphorus in plants and seeds. The results showed that using triple inoculum (Az. chroococcum, Azosp. lipoferum and K. oxytoca) with 75% of nitrogenous fertilizer (33.75 kg N/feddan) achieved the highest seed yield per plant (24.35 g/plant), while oil percent in seeds was 46.86%, which was not the highest but very close to oil percentage in plants treated with the recommended dose of nitrogen, which was 47.47%. On the other side, using bacterial inoculum stimulate microbial population and increased total bacteria, diazotrophs (Azotobacter and Azospirillum) and phosphate dissolving bacteria counts in the rhizosphere of canola plants.

Green manure, seed inoculation with Herbaspirillum seropedicae and nitrogen fertilization on maize yield

ABSTRACT The current need for increase crop yields requires the supplying of nutrients, mainly nitrogen, which increases the production cost, requiring the search for alternative products, such as seed inoculation with diazotrophic bacteria and green manures. In this context, the objective of this study was to evaluate the effect of green manure, seed inoculation with Herbaspirillum seropedicae, and nitrogen fertilization on the productive performance of maize crops. The experiment was conducted at the district of Estiva, in the municipality of Vitória da Conquista, BA, Brazil (14º 52’ 6’’ S, 40º 44’ 55’’ W, and altitude of 917 m), from December 2015 to August 2016. A randomized block design with four repetitions was used, in a 2 × 2 × 2 factorial arrangement, consisting of presence or absence of green manure (velvet bean), seed inoculation with Herbaspirillum seropedicae (strain ZAE94), and mineral nitrogen fertilization (120 kg ha-1). The maize ear length and diameter, number grains per row, ear weight without husks, cob weight, and grain yield were evaluated. A significant triple interaction was found for all evaluated variables. The use of green manure presented better results than the control. Velvet bean can be used as a green manure, as an alternative to soil mineral fertilization without yield losses.

Effect of Mineral and Nano Nitrogen Fertilizers on Yield and Yield Components of Some Yellow Maize Hybrids

Two field experiments were conducted at the Experiment and Research Center, Fac. Agric., Moshtohor, Benha Univ., during 2018 and 2019 summer seasons. The aim of this was to study response of three yellow maize hybrids (SC 2055, SC 176 and SC P3737) to three N fertilizer rates (60, 90 and 120 kg N fed-1) and two Nano-N foliar applications (Without and Nano foliar applications). The experimental design was randomized complete block design (RCBD) using split split-plots arrangement with three replications. The yellow maize hybrids, N fertilizer levels and Nano-N foliar applications were arranged at random in the main plots, sub- plots and sub sub-plots, respectively. Single Cross P3737 was significantly earlier than the other hybrids regarding 50% tasseling and silking. Also, SC P3737 was superior to the other two hybrids in most of the studied traits. The highest values of plant height, ear length, ear diameter, No. grains row-1, ear weight, ear grains weight, 100-grain weight, Forge yield fed-1 and grain yield fed-1 were obtained with fertilizer level of 120 N fed-1. On the other hand, the earliest tasseling and silking were recorded with 60 kg N fed-1. Nano foliar application gave the greatest of all grain yield and attributes of yellow maize hybrids as compared with untreated. It could be concluded that under the conditions of the experiment, planting SC P3737 under 90 or 120 N fed-1 and nano foliar application is recommended.

The Effect of Growth Activators and Plant Growth-Promoting Rhizobacteria (PGPR) on the Soil Properties, Root Yield, and Technological Quality of Sugar Beet

The strategy “from farm to fork” assumes a reduction in the usage of fertilizers and plant protection products in EU agriculture. The aim of this study, conducted over the years 2017–2019 in several locations in Poland, is to evaluate the application of growth activators with and without plant growth-promoting rhizobacteria to reduce mineral nitrogen fertilization without negative effects on the root yield. We studied the effect of these activators on selected soil properties. The experimental treatments included the application of the growth activators Penergetic (K + P) and Azoter, which contains the bacteria Azotobacter chroococcum, Azospirillum brasilense, and Bacillus megaterium, before sowing or during vegetation. The nitrogen rates were reduced by 30% in comparison to full nitrogen mineral fertilization (control treatment). In selected experiments, the application of Penergetic and Penergetic with Azoter caused a higher content of nitrate nitrogen (N-NO3) and ammonium nitrogen (N-NH4) after the sugar beet harvest as well as higher contents of mineral nitrogen (Nmin), P, K, and Mg in the soil in comparison to the treatment with the full dose of mineral nitrogen fertilization. The obtained results proved that it was possible to reduce the mineral application of nitrogen by 30% without a decrease in the biological and pure sugar yield, and even with an increase in the sugar yield caused by the application of the growth activators Penergetic (K + P) and Azoter.

Bentonite-Based Organic Amendment Enriches Microbial Activity in Agricultural Soils

Bentonite-based organic amendments may have the potential to enhance soil microbial properties. The experiment was carried out from 2014 to 2017 comprising four treatments: NPK fertilizer (nitrogen, phosphorus and potassium mineral fertilizer as a control), NPK + cattle manure, NPK + bentonite, and NPK + combination of manure with bentonite (MB) to verify this hypothesis. The effect of treatments on seven different soil microbial properties was measured: dehydrogenase activity (DHA), bacterial phospholipid fatty acid content, fungal phospholipid fatty acid content, microbial biomass carbon (Cmic), 16S rDNA, 18S rDNA, and ammonia-oxidizing bacteria in soil. The results showed that solely bentonite treatment increases the bacterial and fungal biomass, which was further confirmed by the increased 16S rDNA and 18s rDNA gene copy numbers. The only significantly decreased values upon treatment with solely bentonite were recorded for DHA and Cmic. The ammonia-oxidizing bacteria population increased with the sole application of bentonite and reached its maximum value when bentonite was applied with manure. The MB treatment showed the highest value for all seven measured properties. In summary, the application of bentonite solely might increase or decrease the soil activity, but its addition, along with manure, always promotes an abundance of soil microorganisms and their activity. The co-application of bentonite with manure altered the soil microbial properties in a 3-year field experiment in favor of increased microbial biomass, which is beneficial for agriculture and environment and reveals the potential for the restoration of polluted lands.

The comparative analysis of the mineral nitrogen fertilizers

According to the results of physical and chemical modeling, the chemical form of nitrogen fertilizers has a significant effect on the thermodynamic parameters of systems with their application. The chemical activity of nitrogen in sandy soils is higher than in clay soils, and decreases in the series: potassium nitrate - ammonium nitrate - urea - ammonia hydrate, i.e., decreases with the transition from the oxidized form of nitrogen +5 to reduced -3. Potassium and sodium nitrate are optimal with regard to the chemical activity of nitrogen in sandy soils. In clay soils, on the contrary, the maximum activity of nitrogen is provided by the use of urea containing a reduced form of nitrogen. The reactivity of oxygen is higher in clay soils and increases with the transition from oxidized to reduced forms of nitrogen. Therefore, to increase the activity of oxygen in sandy and clay soils, it is preferable to use urea and ammonia water. The binding efficiency of atmospheric nitrogen increases in the series: ammonia hydrate, urea - ammonium nitrate - potassium nitrate, and thus, systems containing highly oxidized nitrogen are favorable for fixing atmospheric nitrogen.

PHOTOSYNTHETIC PARAMETERS OF ALFALFA CROPS IN RELATION TO THE TYPE OF NITROGEN NUTRITION

The paper shows the results of field experiments conducted in 2017-2019. The experiments were devoted to photosynthetic indices of alfalfa in relation to the type of nitrogen nutrition and symbiotic activity of crops. The experiments with alfalfa blue-hybrid were carried out in environmental conditions of the piedmont zone of RNO-Alania on chernozem leached soil with close occurrence of gravel. The researchers compared mineral and symbiotrophic types of nitrogen nutrition of alfalfa plants; they applied mineral nitrogen fertilizers and biospecimens on the basis of rizobium. In natural conditions (control group) the crops formed photosynthetic potential from 1701.3 thousand m²-days/ha per year of sowing to 3624.3 thousand m²-days/ha in the second year of sowing. Crop rates in the third year had intermediate values between the first and second years of crop use. The effect of starting doses of nitrogen fertilizers was observed during the sowing year in its early stages, when the symbiotic system is still underdeveloped and inactive. When estimating the annual average photosynthetic potential, starting nitrogen doses gave an advantage of only 1.6%. Presowing inoculation of seeds by active strains of strawberry bacteria provided the maximum positive effect, while high mountain strains of rizobium were more effective. Average annual parameter of photosynthetic potential varied from 2699.1to3189.4 thousand m² days/ha, increasing with the improvement of nitrogen nutrition. Inoculation of seeds by high-altitude strains of tuber bacteria increased photosynthetic potential to its maximum values or by 18.2%. In the same variant, as well as in the variant with the starting dose of nitrogen, the maximum values of net productivity of photosynthesis were achieved, which exceeded the values of the control variant by 0.09-0.11 g/m²- day.