Forms Of Nitrogen Fertilizers Research Articles

A Protocol for Conducting Rainfall Simulation to Study Soil Runoff

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The objective of this study was to characterize the effects of antecedent soil moisture content on the fate and transport of surface applied commercial urea, a common form of nitrogen (N) fertilizer, following a rainfall event that occurs within 24 hr after fertilizer application. Although urea is assumed to be readily hydrolyzed to ammonium and therefore not often available for transport, recent studies suggest that urea can be transported from agricultural soils to coastal waters where it is implicated in harmful algal blooms. A rainfall simulator was used to apply a consistent rate of uniform rainfall across packed soil boxes that had been prewetted to different soil moisture contents. By controlling rainfall and soil physical characteristics, the effects of antecedent soil moisture on urea loss were isolated. Wetter soils exhibited shorter time from rainfall initiation to runoff initiation, greater total volume of runoff, higher urea concentrations in runoff, and greater mass loadings of urea in runoff. These results also demonstrate the importance of controlling for antecedent soil moisture content in studies designed to isolate other variables, such as soil physical or chemical characteristics, slope, soil cover, management, or rainfall characteristics. Because rainfall simulators are designed to deliver raindrops of similar size and velocity as natural rainfall, studies conducted under a standardized protocol can yield valuable data that, in turn, can be used to develop models for predicting the fate and transport of pollutants in runoff.

A protocol for conducting rainfall simulation to study soil runoff.

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The objective of this study was to characterize the effects of antecedent soil moisture content on the fate and transport of surface applied commercial urea, a common form of nitrogen (N) fertilizer, following a rainfall event that occurs within 24 hr after fertilizer application. Although urea is assumed to be readily hydrolyzed to ammonium and therefore not often available for transport, recent studies suggest that urea can be transported from agricultural soils to coastal waters where it is implicated in harmful algal blooms. A rainfall simulator was used to apply a consistent rate of uniform rainfall across packed soil boxes that had been prewetted to different soil moisture contents. By controlling rainfall and soil physical characteristics, the effects of antecedent soil moisture on urea loss were isolated. Wetter soils exhibited shorter time from rainfall initiation to runoff initiation, greater total volume of runoff, higher urea concentrations in runoff, and greater mass loadings of urea in runoff. These results also demonstrate the importance of controlling for antecedent soil moisture content in studies designed to isolate other variables, such as soil physical or chemical characteristics, slope, soil cover, management, or rainfall characteristics. Because rainfall simulators are designed to deliver raindrops of similar size and velocity as natural rainfall, studies conducted under a standardized protocol can yield valuable data that, in turn, can be used to develop models for predicting the fate and transport of pollutants in runoff.

Environmental analysis of sunflower production with different forms of mineral nitrogen fertilizers

Environmental profiles of mineral nitrogen fertilizers were used to evaluate the environmental disturbances related to their use in cultivation systems in Europe. Since the production of mineral fertilizers requires a large amount of energy, the present study of bioenergy systems is relevant in order to achieve crop yields less dependent on fossil fuels and to reduce the environmental impact due to fertilization.In this study, the suitability of the LCA methodology to analyze the environmental impact of sunflower cultivation systems with different forms of mineral nitrogen fertilizers urea and ammonium nitrate was investigated. Effects on climate change were estimated by the use of Ecoinvent 2.2 database default value for soil N2O emission factor (1%) and local emission data (0.8%) of mineral nitrogen applied to soils.LCA analysis showed a higher impact on environmental categories (human health and ecosystem quality) for the system in which urea was used as a nitrogen source. Use of urea fertilizer showed a higher impact on resource consumption due to fossil fuel consumption. Use of mineral nitrogen fertilizers showed a higher environmental burden than other inputs required for sunflower cultivation systems under study. Urea and ammonium nitrate showed, respectively, a 7.8% and 4.9% reduced impact of N2O as greenhouse gas by using direct field data of soil N2O emission factor compared to the default soil emission factor of 2006 IPCC Guidelines.Use of ammonium nitrate as mineral nitrogen fertilizer in sunflower cultivation would have a lower impact on environmental categories considered. Further environmental analysis of available technologies for fertilizer production might be also evaluated in order to reduce the environmental impacts of each fertilizer.

Występowanie omacnicy prosowianki (Ostrinia nubilalis Hbn.) w zależności od zasobności gleby w azot oraz od formy nawozu azotowego

Summary The aim of the study was to monitor the occurrence of European corn borer on maize plants depending on soil content of nitrogen and forms of nitrogen fertilizer. A significant influence of weather conditions on damage of maize plants caused by caterpillars was observed. It was shown that the percentage of plants with symptoms of pest feeding increased together with an increase in the level of applied nitrogen ranging from 0 to 100 kg N/ha. Maize fertilization with slow-release fertilizers significantly decreased the percentage of plants damaged by the pest in comparison with fast-release nitrogen fertilizers. ES Paroli „stay-green” cultivar revealed a significantly lower susceptibility to European corn borer feeding in comparison with ES Palazzo cultivar.

Nitrate reductase activity in cabbage (Brassica oleracae var. capitata) seedlings affected by the different nitrogen fertilizer forms

The effect of different nitrogen fertilizer (potassium nitrate, ammonium nitrate, ammonium sulphate, urea and farmyard manure) on nitrate reductase activity in cabbage (<i>Brassica oleracea</i> var. <i>capitata</i>) seedlings were studied. pH of the plant growth niedia was higher in the nitrate fertilizer treatment than the ammonium and other fertilizer forms. NO<sub>3</sub><sup>-</sup>-N application increased NRA in plant, but NH<sub>4</sub><sup>+</sup>-N decreased NRA in plant. Harvesting date and different fertilizer doses increased NRA while NH<sub>4</sub><sup>+</sup>-N decreased plant nitrate uptake. There was a significant relationship between NRA and fertilizer types.

Porażenie chorobami roślin dwóch typów odmian mieszańcowych kukurydzy w zależności od formy nawozu azotowego

The aim of the study was to assess the disease infection of plants of two maize cultivar types depending on the applied form of nitrogen fertilizer. It was shown that the type of nitrogen fertilizer significantly affected maize plant infection with the pathogenic fungi of the genus Fusarium ssp. The use of slow‐release nitrogen fertilizers decreased the percentage of maize plants infected by the fusarium diseases in comparison to the treatment with fast‐release nitrogen fertilizers. The advantage of „stay‐green” type cultivar was shown as compared to the classic cultivar. After the application of slow‐release fertilizers, such as: ammonium sulphate and urea, was significantly greater (healthier plants) in terms of the number of plants infected with the fusarium diseases was significantly lower comparing to the treatments: without nitrogen fertilizer use, and after the use of ammonium nitrate, Canwil nitrochalk and a mixture of ammonium nitrate and urea (in a ratio of 50:50). The ES Paroli „stay‐green” hybrid was characterized by a significantly lower percentage of plants infected by the fusarium diseases and corn smut in comparison with the ES Palazzo cultivar. Celem pracy była ocena porażenia chorobami roślin dwóch typów odmian kukurydzy w zależności od formy nawozu azotowego. Wykazano, że rodzaj nawozu azotowego w istotny sposób wpływał na porażenie roślin kukurydzy grzybami z rodzaju Fusarium ssp. Stosowanie nawozów azotowych wolno działających zmniejszało odsetek roślin kukurydzy porażonych przez choroby fuzaryjne w porównaniu do nawozów azotowych szybko działających. Na nawozach wolno działających, takich jak: siarczan amonu i mocznik przewaga odmiany typu „stay‐green” nad odmianą klasyczną pod kątem ilości roślin porażonych przez choroby fuzaryjne była istotnie większa (rośliny zdrowsze) niż na obiektach: bez stosowania nawozu azotowego, saletrze amonowej, saletrzaku Canwil i mieszaninie saletry amonowej z mocznikiem z 50% udziałem każdego z nawozów w dawce nawozu. Mieszaniec ES Paroli typu „stay‐green” charakteryzował się istotnie mniejszym odsetkiem roślin porażonych przez choroby fuzaryjne oraz głownię kukurydzy w porównaniu do odmiany ES Palazzo.

The form of nitrogen nutrition affects resistance against Pseudomonas syringae pv. phaseolicola in tobacco

Different forms of nitrogen (N) fertilizer affect disease development; however, this study investigated the effects of N forms on the hypersensitivity response (HR)—a pathogen-elicited cell death linked to resistance. HR-eliciting Pseudomonas syringae pv. phaseolicola was infiltrated into leaves of tobacco fed with either or . The speed of cell death was faster in -fed compared with -fed plants, which correlated, respectively, with increased and decreased resistance. Nitric oxide (NO) can be generated by nitrate reductase (NR) to influence the formation of the HR. NO generation was reduced in -fed plants where N assimilation bypassed the NR step. This was similar to that elicited by the disease-forming P. syringae pv. tabaci strain, further suggesting that resistance was compromised with feeding. PR1a is a biomarker for the defence signal salicylic acid (SA), and expression was reduced in -fed compared with fed plants at 24h after inoculation. This pattern correlated with actual SA measurements. Conversely, total amino acid, cytosolic and apoplastic glucose/fructose and sucrose were elevated in - treated plants. Gas chromatography/mass spectroscopy was used to characterize metabolic events following different N treatments. Following nutrition, polyamine biosynthesis was predominant, whilst after nutrition, flux appeared to be shifted towards the production of 4-aminobutyric acid. The mechanisms whereby feeding enhances SA, NO, and polyamine-mediated HR-linked defence whilst these are compromised with , which also increases the availability of nutrients to pathogens, are discussed.

Impact of applying different nitrogen fertilizers on the level of fumonisins in maize hybrids grainWpływ stosowania różnych nawozów azotowych na poziom stężenia fumonizyn w ziarnie różnych odmian mieszańcowych kukurydzy

Summary Fusarium is one of the major fungal genera associated with maize. Among mycotoxins synthesized by Fusarium spp. fumonisins are the main of toxicologically and economically important contaminants of maize-based foods and feeds throughout the world. The present study shows the influence of soil supplementation with different forms of nitrogen fertilizers on the level of fumonisins in grain of two different types of corn cultivars. A higher mean level of fumonisins was found in grain of ES Palazzo cultivar in comparison with ES Paroli SG cultivar. The greatest content of fumonisins in grain was observed when no nitrogen fertilization was used, and the lowest when ammonium nitrate and urea with 50% content of each fertilizer in total nitrogen dose were applied.

INFLUENCE OF NITROGEN SUPPLY ON CADMIUM ACCUMULATION IN POTATO TUBERS

The effect of different levels and forms of nitrogen (N) fertilizer on cadmium (Cd) concentrations in potato (Solanum tuberosum L.) tubers, a large component of the northern European diet, was investigated with the aim of decreasing the Cd content. A high and a low Cd-accumulating cultivar were used in two field trials and a pot experiment. The N fertilizers tested were balanced N- phosphorus (P)- potassium (K) 11-5-18 + micronutrients, alkaline calcium nitrate and acidic ammonium sulfate at levels of 60, 160, and 240 kg N ha−1 at planting or (for the higher N doses) split between two or three occasions. The Cd concentration in tubers of both cultivars decreased when increasing the N fertilizer from 60 to 160 or 240 kg N ha−1, indicating that Cd uptake and translocation are not positively correlated to the growth rate of the potato plant. A strong positive linear correlation was found between the Cd concentration in leaves at 77 days after planting and the Cd concentration in tubers at harvest, irrespective of N treatment, although the Cd concentration was three-fold higher in the leaves. The genetic variation in leaf and tuber Cd accumulation was consistent, regardless of the form of N fertilizer used. Ammonium sulfate decreased soil pH and increased tuber Cd concentration in both cultivars compared with NPK fertilizer, possibly due to increased amounts of plant-available Cd arising from the pH decrease after ammonium sulfate application. The tuber Cd concentration in the low Cd-accumulating cultivar increased when fertilized with calcium nitrate, an effect attributed to Cd availability being influenced by the increased Ca2+ concentration.

토양 pH와 질소 관비 비종에 따른 토마토 생육 및 토양화학성 변화

이 실험은 관비재배시 토양 pH와 질소 비종이 토마토 생육과 토양화학성에 미치는 영향에 대해 조사하고자 수행하였다. 시험작물은 동양계 품종인 '슈퍼도태랑'을 이용하여 18 L포트에서 3개월간 재배하였으며 토양 pH를 6.88과 8.77 두수준으로 조절하였다. 주요 관비 비종인 요소, 질산암모늄, 황산암모늄, 질산칼륨를 이용하였으며 관비 농도는 0, 10, 50, 100 mg N/L로 조절하였다. 토양의 pH가 8.77일 때 pH 6.88에 비하여 수량과 엽록소 형광반응이 감소하였으나 질산암모늄과 황산암모늄을 이용하여 관비할 경우 토마토 수량이 증가하는 것으로 나타났다. pH 6.88일 경우 비종보다는 관비 농도가 증가할수록 수량이 증가하였다. 토마토 재배후 비종에 따른 화학성 변화를 살펴보면 토양의 pH는 질산암모늄과 황산암모늄을 시용하였을 경우 감소하였으며 질산 칼륨 시용 시 토양 pH와 칼륨함량이 높아졌다. 토양 내 EC는 황산암모늄 100 mg N/L 시용 시 다른 비종에 비하여 2배 이상 높아졌다. 질산태질소와 암모늄태 질소는 비종별로 크게 차이는 없었지만 pH가 높을 때 토양 내 함량이 적은 것으로 나타났다. 이 실험 결과 요소와 질산암모늄을 관비용 비종으로 이용하면 토마토 재배 전 후 토양화학성의 변화가 크지 않은 것으로 나타났다. This study was conducted to determine effects of soil pH and form of nitrogen fertilizers on tomato growth and chemical properties of greenhouse soil using ferigation system. Tomato (Lycopersicon esculentum Mill. cv. Superdoterang) were grown for three months in 18 L pots filled with two soil (pH 6.8 and pH 8.7). 4 different nitrogen fertilizers (urea, ammonium nitrate, ammonium sulfate, and potassium nitrate) were fertigated with different concentrations of 0, 10, 50, and 100 mg N/L during tomato cultivation. Soil pH 8.7 decreased yield and chlorophyll fluorescence compared with soil pH 6.8. Yield at soil pH 8.7 increased by ammonium nitrate and ammonium sulfate fertigation. Soil pH 6.8 induced increment of yield by nitrogen concentration than form of nitrogen fertilizers. Soil pH after cultivation of tomato decreased by application of ammonium nitrate and ammonium sulfate. Soil EC by 100 mg N/L application of ammonium sulfate was twice as much as other fertilizers. Form of nitrogen fertilizer had less effect on concentration of soil <TEX>$NH_4^+$</TEX>-N and <TEX>$NO_3^-$</TEX>-N in soil but the concentrations slightly reduced at pH 8.7. These results indicate that application of urea and ammonium nitrate for a nitrogen source of fertigation has little affects on soil chemical properties before and after tomato cultivation.

Effectiveness of Chloride Compared to 3,4-Dimethylpyrazole Phosphate on Nitrification Inhibition in Soil

Microbial oxidation of ammonium to nitrate may impose dangers to ecosystem functioning through soil and atmosphere contamination with end products or intermediate gases. A wide range of chemicals can inhibit nitrification under soil and laboratory conditions. In the present study, the effectiveness of chloride compared to 3,4-dimethylpyrazole phosphate (DMPP) as a standard nitrification inhibitor was evaluated. The results showed that DMPP (especially with double concentrations) inhibited nitrification for a longer time, until the end of incubation period. Chloride in the form of ammonium chloride (NH4Cl) or potassium chloride (KCl) also significantly inhibited nitrification compared to the control during the 7-week incubation period. This inhibition was positively correlated with applied chloride concentrations in soil. During a 5-week incubation period, the strongest concentration (500 mg/kg soil) showed more inhibition than concentrations of 250 or 100 mg/kg soil, particularly when compared to control. The results suggest that beside commercial nitrification inhibitors, chloride can significantly inhibit microbial nitrification in soil. Therefore, when chloride is not a soil problem, the chloride form of nitrogen fertilizers (e.g., ammonium chloride) could be a proper nitrogen fertilizer.

Cold Tolerance of Container-grown Green Ash Trees Is Influenced by Nitrogen Fertilizer Type and Rate

A study was conducted to determine whether nitrogen (N) application rate and fertilizer form are related to cold tolerance of buds and stems using container-grown ‘Summit’ green ash (Fraxinus pennsylvanica) trees. Trees were grown with different rates of N from either urea formaldehyde (UF) or a controlled-release fertilizer (CRF) containing ammonium nitrate during the 2006 growing season; and growth, N and carbon (C) composition, and cold tolerance were evaluated in Oct. 2006, Dec. 2006, and Feb. 2007 by assessing the lowest survival temperature (LST) of stem and bud tissues on current season (2006) stems. Both fertilizer type and rate influenced the bud and stem LSTs. The influence of fertilizer rate was most evident on midwinter (December) stem LSTs and the influence of fertilizer type was observed in bud and stem LSTs during the deacclimation period in February. Higher LSTs were associated with higher N concentrations and lower C/N ratios; however, stems and buds of trees fertilized with UF were more cold-tolerant (had lower LSTs) than stems and buds on trees fertilized with CRF. Fertilizer type resulted in several differences in N and C translocation and metabolism during the fall and winter. Our results indicate trees with a similar N status are able to withstand different levels of cold depending on the rate of N and the type or form of fertilizer used during production. This may have to do with differences in how trees metabolize the different fertilizer forms, where and when the N is stored, and how it is remobilized in the spring, especially in relation to C metabolism.

The effect of nitrogen fertilizer form and foliar application on the concentrations of twenty-five elements in carrot

Abstract Among all elements taken into consideration in this research (Al, As, B, Ba, Be, Bi, Ca, Co, Cr, Fe, Ga, In, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, Ti and V), only the concentration of Na in the ‘Kazan F1’ carrot was affected by the interaction of foliar application and nitrogen fertilization. In the case of plants fertilized by Ca(NO3)2, foliar application significantly raised Na concentration in storage roots. Compared to the control, all applied nitrogen fertilizers (results analysed independently from the foliar application factor) increased concentrations of Mg and Se in carrot. Fertilization with (NH4)2SO4 resulted in a decrease of Ba and Mo concentrations and an increase of Mn concentration, while fertilization with Ca(NO3)2 raised the contents of Sr and Be in carrot. Foliar application (analysed independently from nitrogen fertilization) considerably increased Bi and Be concentrations, yet it did not affect the contents of other elements in storage roots.

Emission of CO 2 and N 2O from soil cultivated with common bean ( Phaseolus vulgaris L.) fertilized with different N sources

Addition of different forms of nitrogen fertilizer to cultivated soil is known to affect carbon dioxide (CO 2) and nitrous oxide (N 2O) emissions. In this study, the effect of urea, wastewater sludge and vermicompost on emissions of CO 2 and N 2O in soil cultivated with bean was investigated. Beans were cultivated in the greenhouse in three consecutive experiments, fertilized with or without wastewater sludge at two application rates (33 and 55 Mg fresh wastewater sludge ha − 1 , i.e. 48 and 80 kg N ha − 1 considering a N mineralization rate of 40%), vermicompost derived from the wastewater sludge (212 Mg ha − 1 , i.e. 80 kg N ha − 1 ) or urea (170 kg ha − 1 , i.e. 80 kg N ha − 1 ), while pH, electrolytic conductivity (EC), inorganic nitrogen and CO 2 and N 2O emissions were monitored. Vermicompost added to soil increased EC at onset of the experiment, but thereafter values were similar to the other treatments. Most of the NO 3 − was taken up by the plants, although some was leached from the upper to the lower soil layer. CO 2 emission was 375 C kg ha − 1 y − 1 in the unamended soil, 340 kg C ha − 1 y − 1 in the urea-amended soil and 839 kg ha − 1 y − 1 in the vermicompost-amended soil. N 2O emission was 2.92 kg N ha − 1 y − 1 in soil amended with 55 Mg wastewater sludge ha − 1 , but only 0.03 kg N ha − 1 y − 1 in the unamended soil. The emission of CO 2 was affected by the phenological stage of the plant while organic fertilizer increased the CO 2 and N 2O emission, and the yield per plant. Environmental and economic implications must to be considered to decide how many, how often and what kind of organic fertilizer could be used to increase yields, while limiting soil deterioration and greenhouse gas emissions.

Effects of different forms of nitrogen fertilizers on arsenic uptake by rice plants

A pot microcosm experiment was conducted to investigate the effect of different forms of N fertilizers on As uptake by rice. Compared to a nontreated control, addition of nitrate reduced Fe(II) concentration in soil solution, while treatment with ammonium enhanced Fe(III) reduction, probably coupled to NH(4)(+) oxidation in the nonrhizosphere. Most-probable-number (MPN) enumerations revealed high densities of nitrate-dependent Fe(II)-oxidizing microorganisms. The addition of nitrate decreased Fe plaque formation on the root surface, accompanied by much lower dissolved Fe(II) concentrations in the rhizosphere soil solution compared to the nonamended control. Nitrate addition also reduced As uptake by the rice plant. These results suggest that nitrate may inhibit Fe(III) reduction and/or stimulate nitrate-dependent Fe(II) oxidation, leading to As coprecipitation with, or adsorption to, Fe(III) minerals in the soil. Although Fe plaque formation on the root surface is reduced, nitrate-dependent stimulation of Fe(II) oxidation and/or inhibition of Fe(III) reduction in the bulk soil sequesters mobile As in the soil, resulting in reduced As uptake by rice.

Selecting Appropriate Forms of Nitrogen Fertilizer to Enhance Soil Arsenic Removal by Pteris Vittata: A New Approach in Phytoremediation

Certain plant species have been shown to vigorously accumulate some metals from soil, and thus represent promising and effective remediation alternatives. In order to select the optimum forms of nitrogen (N) fertilizers for the arsenic (As) hyperaccumulator, Pteris vittata L., to maximize As extraction, five forms of N were added individually to different treatments to study the effect of N forms on As uptake of the plants under soil culture in a greenhouse. Although shoot As concentration tended to decrease and As translocation from root to shoot was inhibited, overall As accumulation was greater due to higher biomass when N fertilizer was added. Arsenic accumulation in plants with N fertilization was 100∼300% more than in the plants without N fertilization. There were obvious differences in plant biomass and As accumulation among the N forms, i.e., NH4HCO3, (NH4)2SO4, Ca(NO3)2, KNO3, urea. The total As accumulation in the plants grown in As-supplied soil, under different forms of N fertilizer, decreased as NH4HCO3>(NH4)2SO4 > urea > Ca(NO3)2 >KNO3>CK. The plants treated with N and As accumulated up to 5.3∼7.97 mg As/pot and removed 3.7∼5.5% As from the soils, compared to approximately 2.3% of As removal in the control. NH4 +-N was apparently more effective than other N fertilizers in stimulating As removal when soil was supplied with As at initiation. No significant differences in available As were found among different forms of N fertilizer after phytoremediation. It is concluded that NH4 +-N was the preferable fertilizer for P. vittata to maximize As removal.

AtDUR3 represents the major transporter for high‐affinity urea transport across the plasma membrane of nitrogen‐deficient Arabidopsis roots

Despite the fact that urea is a ubiquitous nitrogen source in soils and the most widespread form of nitrogen fertilizer used in agricultural plant production, membrane transporters that might contribute to the uptake of urea in plant roots have so far been characterized only in heterologous systems. Two T-DNA insertion lines, atdur3-1 and atdur3-3, that showed impaired growth on urea as a sole nitrogen source were used to investigate a role of the H+/urea co-transporter AtDUR3 in nitrogen nutrition in Arabidopsis. In transgenic lines expressing AtDUR3-promoter:GFP constructs, promoter activity was upregulated under nitrogen deficiency and localized to the rhizodermis, including root hairs, as well as to the cortex in more basal root zones. Protein gel blot analysis of two-phase partitioned root membrane fractions and whole-mount immunolocalization in root hairs revealed the plasma membrane to be enriched in AtDUR3 protein. Expression of the AtDUR3 gene in nitrogen-deficient roots was repressed by ammonium and nitrate but induced after supply of urea. Higher accumulation of urea in roots of wild-type plants relative to atdur3-1 and atdur3-3 confirmed that urea was the substrate transported by AtDUR3. Influx of 15N-labeled urea in atdur3-1 and atdur3-3 showed a linear concentration dependency up to 200 microM external urea, whereas influx in wild-type roots followed saturation kinetics with an apparent Km of 4 microM. The results indicate that AtDUR3 is the major transporter for high-affinity urea uptake in Arabidopsis roots and suggest that the high substrate affinity of AtDUR3 reflects an adaptation to the low urea levels usually found in unfertilized soils.

Influence of liming and form of nitrogen fertilizer on nutrient uptake, growth, yield, and quality of Virginia (flue-cured) tobacco

Soil acidity is a limiting factor affecting the growth and yield of many crops all over the world. It is recognized that liming is the most common management practice of profitable crop production on acid soils. On the other hand, it is well-known that the form of nitrogen may affect tobacco yield and quality. In this work, the impact of the interaction between three hydrated lime (HL, Ca(OH) 2) rates (0, 1.5 and 3 t HL ha −1) and three nitrogen fertilizer forms (NO 3-N 100%, NH 4-N 100% and NO 3-N 50% plus NH 4-N 50%) on growth, yield and quality characteristics of Virginia (flue-cured) tobacco was investigated in a 4-year (1995–1998) field experiment established in an acid soil (pH water 1:1 5.3) located in Northern Greece. Lime was applied only once in December 1994, while nitrogen fertilizer was applied annually before transplanting. The results showed that the effect of liming on tobacco growth was not dependent on time, weather conditions and form of nitrogen fertilizer. Liming increased soil pH, enhanced the early growth of tobacco (within 30 days after transplanting (DAT)) and finally increased the total gross and trade yield of tobacco proportionally to the amount of HL added. However, the quality index (organoleptic characteristics) of the cured product was improved only at the HL application rate of 3 t HL ha −1. Furthermore, liming significantly increased Ca and P concentrations but decreased K concentration in cured tobacco leaves. Tobacco yield increase was attributed to the increase of P uptake. Liming also increased the ash content of cured leaves, whereas it did not significantly affect nicotine, total nitrogen and reducing sugars. The use of ammonium N in fertilizer delayed the early growth of tobacco, reduced the nicotine concentration and increased the reducing sugars concentration of the cured product. Total-N, P, K and Mg concentrations of cured leaves were not significantly affected by the form of nitrogen fertilizer used. The results suggested that an initial application of hydrated lime at a rate of 3 t HL ha −1 may ameliorate soil acidity and increase the yield and quality characteristics of Virginia tobacco at least over a 4-year period after application, independent of the form of N fertilizer used.

Effective Nutrient Sources for Plant Growth on Bauxite Residue: II. Evaluating the Response to Inorganic Fertilizers

An integral part of managing dust emissions from bauxite residue storage areas in Western Australia is the establishment of native vegetation and dust control crops. Recent changes to local health department regulations preclude the routine use of poultry manure, the previous standard fertilizer for growing dust control crops on bauxite residue sand. This paper reports on a field evaluation of different forms of inorganic fertilizer, to assess their effectiveness as alternatives to poultry manure for supplying nutrients to dust control crops. We compared plant growth and nutrient uptake under different forms of nitrogen (N) and phosphorus (P) fertilizers with additional potassium (K) and trace elements.

Toxic Effect of Cadmium on Rice as Affected by Nitrogen Fertilizer Form

A nutrient solution experiment was conducted to determine the influence of N forms on growth, oxidative stress, and Cd and N uptake in rice plants. The treatments were consisted of two Cd levels (0 and 1 μmol) and three N forms (NH4)2SO4, NH4NO3 and Ca(NO3)2. The results indicated that without Cd addition in the culture solution, the N forms had no significant effect on all measured parameters, including plant growth, photosynthetic traits, malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and Cd and N concentration, while Cd addition in the medium resulted in significant differences in measured parameters among the three forms of N fertilizers. The least inhibition of growth was noted in (NH4)2SO4-fed plants, and the largest in Ca(NO3)2-fed plants, when plants were exposed to Cd stress. The highest photosynthetic rate and chlorophyll content was also recorded in (NH4)2SO4-fed plants. Addition of Cd caused a remarkable increase in SOD activity and MDA content in plants, and the extent of increase varied with N form, with (NH4)2SO4-fed plants being smallest. In comparison with the control plants, the N concentration in roots and shoots was not significantly affected in (NH4)2SO4-fed plants, but significant decrease in root N concentration was found for the NH4NO3 and Ca(NO3)2-fed plants under Cd stress. Moreover, the significant differences were also noted among the three N forms in both root and shoot Cd concentrations, with (NH4)2SO4-fed plants being the lowest. The results indicated that the toxic effect of Cd on rice varied with the form of N fertilizer.