Effect Of Nitrogen Fertilization Research Articles

Nitrous oxide emissions from soybean in response to drained and undrained soils and previous corn nitrogen management.

While corn (Zea mays L.)-soybean (Glycine max. Merr. L) is a predominant rotation system in the US Midwest the residual effect of nitrogen (N) fertilization to corn on the following year's soybean and N2O emissions under different soil drainage conditions has not been studied. Our objective was to quantify agronomic parameters and season-long N2O emissions from soybean as affected by N management (0-N and optimum N rate of 135kg N ha-1 as single or split application) during the previous corn crop under drained and undrained systems. Urea was applied to corn, and residual N effects were measured on soybean the following year in a poorly drained soil with and without subsurface tile drainage. Drainage reduced N2O emissions in one of three growing seasons but had no effect on soybean yield or N removal in grain. Nitrogen management in the previous corn crop had no effect on soybean grain yield, N removal, or N2O emissions during the soybean phase. Even though soybean symbiotically fixes N and removes more N in grain than corn, N2O emissions were more than two times greater during the corn phase (mean=1.83kg N ha-1) due to N fertilization than during the soybean phase (mean=0.80kg N ha-1). Also, N2O emissions in the corn years were increased possibly due to decomposition of the previous year's soybean crop residue compared to corn residue decomposition in the soybean years. Tile drainage, especially where wet soil conditions are prevalent, is a viable option to mitigate agricultural N2O emissions.

Assessment of the Impact of Magnesium and Nitrogen Fertilization on Two Species of Grasses Used as Horse Feed

The aim of this study was to determine the effect of nitrogen (three doses of N) and magnesium (two doses of Mg) fertilization on the yield and quality of fodder obtained from two old and extensive grass species Festulolium braunii cv. ‘Felopa’ and Lolium multiflorum cv. ‘Tur’ in field cultivation under dry conditions. F. braunii was better adapted to cultivation on light, dry soils than L. multiflorum; in such conditions, it produces higher yields of dry matter and protein, characterized by a higher concentration of nutrients. F. braunii fertilized with doses of 120 and 180 kg N∙ha−1 yielded higher than that fertilized with a dose of 60 kg N∙ha−1, and L. multiflorum produced similar yields after applying doses of 60, 120 and 180 kg N∙ha−1. For tested grass pasture, a single N application after the start of vegetation in two forms (fast- and slow-acting) appears to be adequate. Resignation from splitting the nitrogen dose due to variable rainfall distribution that can occur after the first cut during the dry summer is beneficial due to a reduction in the losses of nutrients and environmental burdens.

Synergistic nitrogen fertiliser effects on nitrogen metabolism of wheat in saline-alkaline land

Synergistic nitrogen fertiliser effects on nitrogen metabolism of wheat in saline-alkaline land

Effects of cover crops and nitrogen fertilization on soil physical properties, carbon and nitrogen fractions, and winter wheat yield in the Chinese loess plateau: A 4-year field experiment

Context or problemLone-term application of chemical fertilizers in farmland ensure adequate or profitable crop yields but may damage soil structure. Cover crops (CCs) have great potentials to improve soil quality and promote sustainable crop production. However, the combined impacts of CCs with nitrogen fertilization on soil quality and crop yields are not clear. Objective or research questionWe aimed to examine the effects of CCs combined with N fertilization rates on soil physical properties, C and N fractions in both bulk soils and aggregates, and crop yields, and to find the best management practice that improve both soil quality and crop yields synthetically. MethodsA 4-year summer CCs - winter wheat field experiment was conducted in the Loess Plateau of China. CCs with different species and combinations (CC) were soybean (SB), sudan grass (SG), a mixture of both (SS), and no cover crop (CK) and N fertilizer (NR) were applied to winter wheat at rates of 0 (N0), 60 (N60), and 120 (N120) kg N ha−1. Soil physical properties and C and N fractions in both bulk soils and aggregates were evaluated at 0–10, 10–20, and 20–40 cm soil depths. ResultsSoil total porosity (TP), saturated water content (SWC), capillary water capacity (CWC), and C and N fractions decreased while bulk density (BD) increased with the increase of soil depth. The CC, NR, and their interaction (CC×NR) had significant effects on soil BD, aggregate size distribution and stability (MWD), and C and N fractions and only CC and CC×NR had significant effects on other physical properties. The incorporation of CCs significantly increased the proportions of > 5 mm aggregates and C and N fractions in both bulk soils and aggregates, especially in 0–10 and 10–20 cm. And SB and SS improved soil other physical properties more than SG, especially in 0–10 cm, which decreased BD by 13.2% and 12.6% while increased TP by 6.5% and 8.3%, SWC by 14.3% and 15.3%, CWC by 13.9% and 14.2%, MWD by 16.6% and 14.4%, respectively, compared to CK. Additionally, soil physical properties improved more with N60 while the C and N fractions in both bulk soils and aggregates increased more with N120. However, BD increased by 2.6% and 3.3% in N60 and N120 than N0, respectively. The correlations between the proportion of macro-aggregates and soil C and N fractions at 0–10 and 10–20 cm indicated the positive effects of CCs on improving soil structure and fertility simultaneously. Aggregated-associated C and N fractions decreased firstly and then increased with the reduced aggregate sizes, and were higher in micro-aggregates than in other size classes. N60-SB increased wheat yields by 98.7% compared with N0-CK. ConclusionsOverall, the incorporation of soybean residue was the best management practice for winter wheat yield and soil fertility under the reduced N fertilization. Implications or significanceThe selection of CCs species should depend on farmland managements, and the appropriate CCs with N fertilizer rates would target the improvements in soil quality, the sequestration of soil organic carbon, and crop yields synergistically.

A Systematic Review on Effects of Nitrogen Fertilizer Levels on Cabbage (Brassica oleracea var. capitata L.) Production in Ethiopia.

Cabbage (Brassica oleracea var. capitata L.) holds significant agricultural and nutritional importance in Ethiopia; yet, its production faces challenges, including suboptimal nitrogen fertilizer management. The aim of this review was to review the possible effect of nitrogen fertilizer levels on the production of cabbage in Ethiopia. Nitrogen fertilization significantly influences cabbage yield and quality. Moderate to high levels of nitrogen application enhance plant growth, leaf area, head weight, and yield. However, excessive nitrogen levels can lead to adverse effects such as delayed maturity, increased susceptibility to pests and diseases, and reduced postharvest quality. In Ethiopia, small-scale farmers use different nitrogen levels for cabbage cultivation. In Ethiopia, NPSB or NPSBZN fertilizers are widely employed for the growing of various crops such as cabbage. 242 kg of NPS and 79 kg of urea are the blanket recommendation for the current production of cabbage in Ethiopia. The existing rate is not conducive for farmers. Therefore, small-scale farmers ought to utilize an optimal and cost-effective nitrogen rate to boost the cabbage yield. Furthermore, the effectiveness of nitrogen fertilization is influenced by various factors including the soil type, climate, cabbage variety, and agronomic practices. Integrated nutrient management approaches, combining nitrogen fertilizers with organic amendments or other nutrients, have shown promise in optimizing cabbage production while minimizing environmental impacts. The government ought to heed suggestions concerning soil characteristics such as the soil type, fertility, and additional factors such as the soil pH level and soil moisture contents.

Effects of various nitrogen fertilisers applied in autumn on growth parameters, yield and quality of winter oilseed rape

Effects of various nitrogen fertilisers applied in autumn on growth parameters, yield and quality of winter oilseed rape

Improving prediction accuracy of CSM-CERES-Wheat model for water and nitrogen response using a modified Penman-Monteith equation in a semi-arid region

Context or problemThe implementation of crop models for water and nitrogen management are important in preserving water resources and reducing groundwater pollution. The Decision Support System for Agrotechnology Transfer (DSSAT) is a collection of field-scale process-based crop models that simulate crop growth and yield in response to water and nitrogen management as well as many other factors. Objective or research questionThe objective of this study was to improve the simulation of irrigation and nitrogen fertilizer effects on growth and yield of winter wheat using locally modified Penman-Monteith (PM) equation. Specifically, we focused on improving the estimation of ETo using a locally modified Penman-Monteith (PM) equation in the CSM-CERES-Wheat model. MethodsField measured data from a two-year experiment (2009–2010 and 2010–2011) in a semi-arid region were used to calibrate and evaluate the CSM-CERES-Wheat model in a region with strong advective condition. In this experiment, the irrigation treatments were 1.2, 1.0, 0.8, 0.5 times by full irrigation requirements and rain-fed, and nitrogen treatments were 0, 46, 92, and 136 kg N ha−1. ResultsUsing the CSM-CERES-Wheat model with the unmodified PM equation resulted in some growth variables such as: aboveground dry matter, grain yield, and grain nitrogen uptake with high normalized root mean square error (NRMSE) of 0.51, 0.35, and 0.32, respectively. However, using the modified PM equation for ETo module under semi-arid condition improved the soil water content estimation and the model outputs, such as the above ground dry matter, grain yield and grain nitrogen uptake with NRMSE of 0.2, 0.15 and 0.16, respectively, that are accurate. This modification provided more accurate estimations, particularly in our experimental site in semi-aid region with strong advective conditions. ConclusionsThe findings of this study indicated that the locally modified PM equation in the CSM-CERES-Wheat model enhanced the accuracy of estimating irrigation and nitrogen fertilizer on the growth and yield of winter wheat. By improving the estimation of ETo value, the model's performance in simulating crop responses to water and nitrogen management was significantly enhanced. Implications or significanceThe utilization of the accurately estimated ETo value of the modified PM equation has significant importance in the practical application of the CSM-CERES-Wheat model. Furthermore, this modification greatly enhances the accuracy of model outputs, particularly at our experimental site located in a semi-arid region with robust advective conditions.

Effects of Different N Fertilizer Doses on Phenology, Photosynthetic Fluorescence, and Yield of Quinoa

Quinoa (Chenopodium quinoa Willd.) is gaining recognition as a pseudocereal due to its nutritional attributes and adaptability to challenging conditions and marginal soils. However, understanding the optimal fertilization for quinoa growth remains a challenge. This study investigates the effects of nitrogen fertilization (0, 90, 120, and 150 kg using urea) on quinoa phenology, growth, and photosynthesis in the Loess Plateau region of China, a critical area facing soil erosion and ecological degradation. The results showed that nitrogen fertilization significantly influenced quinoa phenology, prompting early flowering and shorter growth at an optimum rate of 120 kg ha−1. Nitrogen application enhanced growth traits such as plant height, stem diameter, and chlorophyll content, particularly at the heading and flowering stages. Photosynthesis-related parameters, including net photosynthesis rate, transpiration rate, stomatal conductance, and intercellular CO2 concentration, were affected by nitrogen application, with higher values observed at 120 kg ha−1. Non-photochemical quenching was significantly increased by nitrogen application, indicating the efficient dissipation of excess energy. The study demonstrated a positive correlation between grain yield and growth traits, photosynthesis-related traits, and chlorophyll content. In conclusion, quinoa yield could be significantly improved at the Loess Plateau region under rainfed conditions by an optimal nitrogen fertilizer rate of 120 kg ha−1, which reduces the growth duration while increasing photosynthesis traits.

Effect of Nitrogen, Zinc and Iron Fertilization on the Economic Yield of Wheat (Triticum aestivum. L)

The experiment was carried out entitled “Effect of nitrogen fertilizer and Ferti-fortification through zinc and iron on yield and economics of wheat (Triticum aestivum)” at the Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, (U.P.) during rabi season of 2021-22 and 2022-23. The soil of the experimental area was sandy clay loam with low organic matter, available nitrogen, medium in available phosphorus, potassium, zinc, iron and slightly alkaline in reaction. The result of the experiment revealed that the maximum grain yield (52.83 q ha-1 and 51.44 q ha-1), straw yield (66.06 q ha-1 and 65.40 q ha-1), net returns (₹ 106,008 ha-1 and ₹ 112,155 ha-1) and B:C ratio (3.27 & 3.26) was recorded with recommended nitrogen (150 kg N ha-1) + foliar zinc (0.5%) + foliar iron (0.5 %) treatments during 2021-22 and 2022-23, respectively.

Nitrogen fertilization modulates rice phyllosphere functional genes and pathogens through fungal communities

The phyllosphere is a vital yet often neglected habitat hosting diverse microorganisms with various functions. However, studies regarding how the composition and functions of the phyllosphere microbiome respond to agricultural practices, like nitrogen fertilization, are limited. This study investigated the effects of long-term nitrogen fertilization with different levels (CK, N90, N210, N330) on the functional genes and pathogens of the rice phyllosphere microbiome. Results showed that the relative abundance of many microbial functional genes in the rice phyllosphere was significantly affected by nitrogen fertilization, especially those involved in C fixation and denitrification genes. Different nitrogen fertilization levels have greater effects on fungal communities than bacteria communities in the rice phyllosphere, and network analysis and structural equation models further elucidate that fungal communities not only changed bacterial-fungal inter-kingdom interactions in the phyllosphere but also contributed to the variation of biogeochemical cycle potential. Besides, the moderate nitrogen fertilization level (N210) was associated with an enrichment of beneficial microbes in the phyllosphere, while also resulting in the lowest abundance of pathogenic fungi (1.14 %). In contrast, the highest abundance of pathogenic fungi (1.64 %) was observed in the highest nitrogen fertilization level (N330). This enrichment of pathogen due to high nitrogen level was also regulated by the fungal communities, as revealed through SEM analysis. Together, we demonstrated that the phyllosphere fungal communities were more sensitive to the nitrogen fertilization levels and played a crucial role in influencing phyllosphere functional profiles including element cycling potential and pathogen abundance. This study expands our knowledge regarding the role of phyllosphere fungal communities in modulating the element cycling and plant health in sustainable agriculture.

Effect of Nitrogen Fertilizer and Seed Rates on Growth, Yield and Yield Components of Bread Wheat in Jimma Zone South Western Ethiopia

Wheat is one of the most important cereal crops in terms of production and consumption in Ethiopia. The country has the potential to produce a sufficient amount of wheat grain using irrigation, and government also gave attention to produce wheat and export it. But inappropriate agronomic practices, soil fertility depletion, and drought are among the constraints to the low yield of wheat crops in the country. In view of this, the field experiment was conducted during the irrigation season of 2020/2021 in two districts that are selected as irrigation potential and irrigation facilities namely, Sekacokorsa and Tiroafetadistricts of Jimma zone. The field experiment consisted of four N fertilizer rates (0, 23, 46, 69, and 92 kg Nha<sup>-1</sup>) and three seed rates (125, 150, and 175 kg•ha<sup>-1</sup>). The experiment was laid out in a randomized complete block design with a factorial arrangement in three replications. From the field experiment results, the growth, yield and yield components of the crop were improved by optimizing plant population density and nitrogenfertilizerapplication. Numerically the highest grain yield and above ground biomass of 6.7 and 13.09 t•ha<sup>-1</sup>at Tiroafeta and 3.67 and 9.61 t•ha<sup>-1</sup> at Sekacokorsawas recorded in response to the seed rate of 175 kg•ha<sup>-1</sup> respectively. On other hand in response to N fertilizer rate the maximum grain yield of 6.9 t•ha<sup>-1</sup>and above ground biomass of 14.04 t•ha<sup>-1</sup> at Tiroafetawas recorded from 92kg N ha<sup>-1</sup>and 69 kg N ha<sup>-1</sup> respectively. Whereas at Sekacokorsa the highest grain yield of 3.72 t•ha<sup>-1</sup>and above ground biomass of 9.76 t•ha<sup>-1</sup> was obtained from nitrogen fertilizer rate of 46kg N ha<sup>-1</sup>. In conclusion, N fertilizer rate of 46kg•Nha<sup>-1</sup> and seed rates of 125 kg•ha<sup>-1</sup>in both locationsgavethe optimum yield. But due to the field experiment was done for one year only it should be repeated over the years to give sound recommendationsunder similar agro ecologies.

Assessing the Impact of Nitrogen Fertilization, Variety Selection, Year and Their Interaction on Wheat Yield and Yield Components

This five-year study (2016–2021) in Morocco’s Mediterranean climate investigated the effect of nitrogen fertilization and genotypic selection on wheat yield and associated components. Utilizing a split-plot design, the study assessed five wheat genotypes—’Faraj’, ‘Luiza’, ‘Itri’, ‘Karim’ and ‘Nassira’—under three nitrogen application rates (120, 60 and 0 kg/ha) across thirty plots with two replicates. Interactions between nitrogen and year showed marked significance in yield (p = 0.001), biomass (p = 0.002), TKW (p = 0.003) and Spk/m2 (p = 0.001), underscoring the variability in optimal nitrogen application rates across different years. Additionally, significant interactions between variety and year were observed for biomass (p = 0.001) and G/m2 (p = 0.001), indicating variability in the performance of different varieties across years. The ‘Itri’ genotype showed the highest yield in 2017, while ‘Luiza’ was pre-eminent in 2018, with ‘Itri’ producing the most biomass. ‘Faraj’ demonstrated consistent superiority in yield and biomass during 2019 and 2020. Our integrated principal component analysis and quadratic models elucidated that an intermediate nitrogen rate of 60 kg/ha (N2) was particularly advantageous for the ‘Faraj’ and ‘Karim’ genotypes. These findings highlight the substantial impact of informed nitrogen level adjustment and genotypic selection on yield optimization.

Modeling the effect of fertilizers on cotton yields and cotton fiber quality on saline soils in so uthern Kazakhstan

Yntymak st.,26, Kazakhstan Cotton in Kazakhstan is one of the strategically important crops and is cultivated in the extreme south of the republic in the Turkestan region, in the northernmost cotton-growing zone on the globe. The aridity of the climate, the shortage of irrigation water and the growing threat of the risk of increasing saline lands in cotton plantations, on the one hand, and the insufficient and unjustified use of minerals, on the other, are the main limiting factors in cotton production. On the industrial plantations of the peasant farm "Sabyr", v. Atakent, Maktaaral district, Turkestan region, field experiments were carried out on serozems of slightly and moderately salinity in 2022. In experiments on two salinity backgrounds, 9 identical treatments of fertilizers with different doses and ratios of nitrogen, phosphorus and potassium were studied. During the phases of budding, flowering and fruit formation of cotton, biometric studies and selection of plant samples were carried out to study photosynthetic and yield indicators depending on fertilizers on 2 salinity backgrounds. The effect and interaction of fertilizers and the amount of salts in the soil on the formation of leaves in various phases of cotton development isquite accurately described (R2 = 0,957-0,972) by regression equations. At the same time, the effect of single action of nitrogen and potassium fertilizers was negative, and that of phosphorus fertilizers was positive. During the growing season, double combinations of all the studied factors, with the exception of nitrogen and potassium, had a negative effect on the dynamics of accumulation of cotton plant biomass. The gross cotton yield is 86% determined by the complex total influence of nitrogen, phosphorus and potassium fertilizers and the degree of soil salinity. At the same time, the unilateral effect of nitrogen and potassium fertilizers and soil salinity on cotton yield was negative, and that of phosphorus fertilizer was positive. There is a high correlation between potassium nutrition and fiber quality indicators (r = 0,38-0,62). Changes in fiber quality indicators generally had a strong relationship with the amount of salts in the topsoil (r = 0,51-0,61).

Polyphenol Profile, Antioxidant Activity and Yield of Cynara cardunculus altilis in Response to Nitrogen Fertilisation

Cardoon leaves are of great pharmaceutical importance due to their high content of polyphenol compounds. Polyphenolic compounds have attracted much interest due to their health-promoting effects. The content of these compounds in C. cardunculus depends on several factors, such as genotype, crop management, plant tissues, harvest time, and storage time. In this study, the effects of nitrogen (N) fertilisation (rates and forms) on the biomass yield and polyphenol profile of the leaves were determined. Increasing the amount of N up to 180 kg-ha−1 in fertilisation did not significantly increase the air-dried biomass yield of the leaves. On the contrary, it led to lower concentrations of total phenolic compounds (TP), total flavonoids (TF), caffeic acid, cynarin, and luteolin. Improvements in performance were achieved when 120 kg-ha−1 N rate was applied and increases in TP, TF content, and radical scavenging activity were observed. The applied N forms (NO3, NH4 or urea) had different effects on the concentrations of individual compounds and leaf air-dried biomass. Higher concentrations of cynarin, luteolin, and luteolin-7-O-glucoside were found when the N forms NH4 and urea were applied; higher caffeic acid content was found when urea was applied. The application of NO3 and urea in fertilisation reduced the level of luteolin-7-O-rutinoside, while the application of NO3 and NH4 reduced the amount of caffeic acid. The obtained results provide a better understanding of the effects of N rates and forms on cardoon leaves over two growing seasons.

Response of chickpea's yield and yield components to double inoculation with mycorrhiza and rhizobium under split application of nitrogen

AbstractThe utilization of advantageous microorganisms as a biofertilizer has gained significant importance in the agricultural industry due to their potential contribution to food safety and the sustainable cultivation of crops. To evaluate the effect of nitrogen (N) fertilizer and co‐inoculation with arbuscular mycorrhiza and rhizobium on the yield and yield component of chickpea (Cicer arietinum L.), a 2‐year field experiment was conducted in 2020–2021 at the Agricultural Research Station of Ferdowsi University of Mashhad, Iran. The experiment was designed as a randomized block trial in factorial design with three replicates. The treatments included two levels of inoculation (noninoculated and inoculated with rhizobium and mycorrhiza) and application of different levels of N fertilizer (0, 25, or 50 kg ha−1) at three growth stages (sowing, flowering, pod filling) as follows; F0 (0,0,0), F1 (25,0,0), F2 (25,25,0), F3 (25,25,25), F4 (50,0,0), F5 (50,50,0) and F6 (50,50,50), respectively. The results showed that seed inoculation and split N fertilization significantly increased yield and yield components in chickpea (Cicer arietinum L.). Seed inoculation showed the highest values for all traits studied compared to the noninoculated treatments. Moreover, among the fertilizer treatments, the highest values for plant height (41.8 cm), number of branches (9.1), number of grains per plant (17.8) and 100‐grain weight (30.4 g) from F6 through the F3 treatment, were statistically similar. The results show that the effect of inoculation is more significant when a lower amount of N fertilizer is applied. Due to the health and environmental problems associated with chemical fertilizers, double inoculation and split application of N fertilizers at lower doses can be recommended.

Aeschynomene overseeding and nitrogen fertilization effects in bahiagrass litter decomposition

AbstractProductivity of tropical and subtropical grasslands is often limited by inadequate nitrogen (N) supply. Aeschynomene (Aeschynomene americana L.) is a warm‐season legume that may contribute as N input in grazing systems, but there is limited information about aeschynomene litter decomposition and N dynamics on pastures. The objective of this study was to quantify the effect of overseeding aeschynomene or applying N fertilizer to existing bahiagrass (Paspalum notatum Flüggé) on litter disappearance and decomposition rates. The study was conducted in Ona, FL, from October 2019 to May 2020 and October 2020 to May 2021. Treatments were the split‐plot arrangement of bahiagrass‐aeschynomene or bahiagrass monoculture (main plot) and N fertilization level, (0 [control] or 60 kg N ha−1) as subplot, distributed in a randomized complete block design with four replicates. The nylon bag technique was used to estimate organic matter (OM), N and carbon (C) disappearance, and lignin concentration for 184 days of incubation. Bahiagrass‐aeschynomene had greater OM disappearance (from 330 to 356 g kg−1 OM) and was driven by C disappearance. Nitrogen fertilization did not impact litter decomposition responses, except for C:N ratio. Overseeding aeschynomene is an effective management practice to increase OM decomposition and optimize nutrient cycling in warm‐season pastures.

Effect of weather, nitrogen fertilizer, and biostimulators on the root size and yield components of Hordeum vulgare

Abstract In this study, the effect of nitrogen doses (52, 80, 110, 140 kg/ha N) and the application of biostimulant preparations containing Ascophyllum nodosum L. algae extract were assessed. During the years 2018–2019, the influence of the preparations on the electrical capacity of the roots (C R) and yield components of spring barley was determined. Root electrical capacitance was determined in growth stages 45–50, 55–65, and 70–75 according to the BBCH-scale. The best phases of vegetation growth for the application of biostimulators with Ascophyllum nodosum extract were the barley tillering and elongation phases. This application increased C R while reducing the amount of N required to achieve similar or higher production of barley yield components compared to high N treatments. The root electrical capacitance, the number of productive tillers, and the number of grains per plant were significantly influenced (p > 0.05) by the weather of the year. The number of productive tillers was closely correlated with C R (r = 0.912**) as well as the number of grains per plant (r = 0.859**) and their weight (r = 0.850**). These relationships were the highest at the beginning of the grain formation (BBCH 70–75). Foliar biostimulation was not very effective in the dry year of 2018. The problem may be the foliar application itself. The effect of foliar application is strongly dependent on weather conditions and may be ineffective in many cases. We recommend the foliar application of effective biostimulants in tillering and elongation phases. They can reduce production costs and environmental pollution by reducing the amount of fertilizer needed while maintaining yields.

Assessment of the presence of nitrates and other chemicals in soil and in maize plants by nitrogen fertilization

The main purpose of this study was to evaluate the effect of nitrogen fertilization, with different levels and type of fertilizers, on the agrochemical evolution of the soil superficial horizon and on nitrates levels in maize leaves in different growth stages (5 leaves, flowering and milk maturity). Two type of nitrogen fertilizers (Ammonium nitrate and Urea) and five nitrogen levels (80 kg/ha; 120 kg/ha; 200 kg/ha and 240 kg/ha) were applied in experimental trails. Filed experiments were conducted at the Agricultural Research and Development Station (ARDS) of Suceava, Romania, during years 2021 and 2022. The pH of the soil in the conditions of fertilization with ammonium nitrate, was acid with values between 4.88—4.65 in the first vegetation stages, and between 4.36—4.3 at the end of the vegetation period. Referring to response of maize plant to the fertilization levels and type of fertilizers showed some influences on chemical content of maize leaves in different growth stages. Concerning the presence of nitrates in maize plants, this study showed that the nitrates contents was highest in the first growth stage of maize plants, particularly when ammonium nitrate fertilizer was used.

67Zn and 111Cd labelled green manure to determine the fate and dynamics of zinc and cadmium in soil–fertilizer–crop systems

ABSTRACT Isotope source tracing enables to accurately determine the fate of nutrients that are applied with fertilizers to soils. While this approach is well established for major nutrients such as nitrogen, it is not yet established for trace metals. Here, we aimed to determine the fate of the micronutrient zinc (Zn) and the contaminant cadmium (Cd) that were applied with an organic fertilizer to a soil–wheat system. A pot study was conducted in which wheat was grown on an alkaline soil. The soils received green manure and/or soluble Zn fertilizer and were compared with non-fertilized control treatments (n = 4 experimental replicates). The green manure was labelled with the stable isotopes 67Zn and 111Cd. For an efficient sample throughput, a method was provided and validated to determine enriched stable isotope ratios (67Zn:66Zn and 111Cd:110Cd) and the Zn and Cd concentrations in one analytical run. To this end, single collector ICP-MS analyses and stable isotope mass balances calculations were combined. Applying this method revealed that the addition of green manure increased neither Zn nor Cd concentrations in wheat grains due to biomass dilution effects. Isotope source tracing showed that the largest fraction of these metals in the wheat shoots derived from the soil in all treatments (Zn 87–99 %, Cd 94–98 %). Moreover, the addition of green manure increased the transfer of Zn and Cd from soil to wheat by a factor 1.9 for both elements. This increased transfer was likely related to a nitrogen fertilization effect that increased root and shoot biomass and thereby the soil exploration of the wheat. This study demonstrated how the fate and dynamics of multiple trace metals can be efficiently determined in soil–fertilizer–crop systems using isotope source tracing.

Synergistic effects of planting density and nitrogen fertilization on chlorophyll degradation and leaf senescence after silking in maize

Regulating planting density and nitrogen (N) fertilization could delay chlorophyll (Chl) degradation and leaf senescence in maize cultivars. This study measured changes in ear leaf green area (GLAear), Chl content, the activities of Chl a-degrading enzymes after silking, and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates. The dynamic change of GLAear after silking fitted to the logistic model, and the GLAear duration and the GLAear at 42 d after silking were affected mainly by the duration of the initial senescence period (T1) which was a key factor of the leaf senescence. The average chlorophyllase (CLH) activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content, indicating that CLH is a key enzyme for degrading Chl a in maize. Increasing density increased the CLH activity and decreased the Chl content, T1, GLAear, and GLAear duration. Under high density, appropriate N application reduced CLH activity, increased Chl content, prolonged T1, alleviated high-density-induced leaf senescence, and increased post-silking dry matter accumulation and grain yield.