Growth and Accumulation of Nitrogen and Potassium in Flue‐Cured Tobacco as Affected by Calcium Nitrate and Ammonium Nitrate

The process of biomass, nitrogen (N), and potassium (K) accumulation over time as affected by N forms is poorly understood. The objective of this study was to identify the effects of N form on growth as well as on N and K nutrition of flue‐cured tobacco plants (Nicotiana tobaccum L.). The plants were grown in a greenhouse with pots of soil for 117 days after 200 days of preculture. Three treatments (calcium nitrate [Ca(NO₃)₂], ammonium nitrate (NH₄NO₃), and ammonium nitrate plus straw (NH₄NO₃ + straw)) were used. The results showed that there were no significant differences in shoot dry mass of tobacco among the three treatments during the entire growth stage except at 30 and 117 days after transplanting. At these two growth stages, shoot biomass with the Ca(NO₃)₂ treatment was significantly less than that with NH₄NO₃ with or without straw. The NH₄NO₃ + straw plants had more mature leaves and greater leaf dry weight than the other two treatments. At an early stage (before 66 days), N concentration of Ca(NO₃)₂‐fed plants was less than with the other two treatments. The leaf K concentration and shoot K content of NH₄NO₃ and NH₄NO₃ + straw plants were more than with the Ca(NO₃)₂ treatment before maturity. Also, K concentration in mature leaves with these two treatments was greater than with Ca(NO₃)₂ treatment. All these results indicated that NH₄NO₃ application had benefits to the maturity and K accumulation in leaves of tobacco.     

Effect of Straw Incorporation on 15N‐Labeled Ammonium Nitrogen Uptake and Rice Growth

Abstract

A greenhouse experiment was conducted to determine the effect of rice straw residue on growth and uptake of added ¹⁵N‐labeled ammonium nitrogen (NH₄‐N) (3% ¹⁵N abundance at the rate of 150 kg N ha^?) by rice in Crowley silt loam soil (Typic Albaqualfs). Higher rates of rice straw addition had an adverse affect on plant growth from the first to sixth week. After 6 weeks, the high rice straw treatment had a positive effect on plant growth (P<0.05). The ¹⁵N‐labeled ammonium or fertilizer nitrogen (N) uptake by rice was significantly lower (P<0.05) in the high rice straw treatment as compared to lower rice straw treatments. Greater plant growth was recorded under alternate flooding and draining condition as compared to continuously flooded treatment (P<0.01).     

Analysis of Arsenic Uptake by Plant Species Selected for Growth in Northwest Ohio by Inductively Coupled Plasma–Optical Emission Spectroscopy

Abstract

Arsenic (As) contamination is widespread in the industrial areas of northwest Ohio. Plant species that both take up As and are appropriate for the climate and growth conditions of the region are needed for phytoremediation to be successfully employed. Actively growing plants from 22 species of native genera were exposed to As in hydroponics systems (either 0, 10, or 50 mg As L^?1; 1 week) and commercially available potting mix (either 0, 10, 25, 100, or 250 mg As L^?1; 2 weeks), depending on their growth conditions. Aboveground plant tissues were harvested and digested, and concentrations of As were determined by inductively coupled plasma–optical emission spectrometry. The highest tissue concentrations of As (mg As kg^?1 dw) were recorded in seven plant species: Rudbeckia hirta (661), Helenium autumnale (363 in tissues formed after exposure to As), Lupinus perennis (333), Echinacea purpurea (298), Coreopsis lanceolata (258), Lepidium virginicum (214), and Linum lewisii (214). These seven species are ecologically diverse, which suggests that phytoremediation of As using diverse assemblages of plants may be an option for a variety of environments.     

Determination of Major and Trace Elements in Plant Samples by Inductively Coupled Plasma–Mass Spectrometry

The determination of several trace elements [arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), and lead (Pb)] in plant samples using inductively coupled plasma–mass spectrometry (ICP‐MS) was evaluated. It was established experimentally that moderate amounts (0.2–2%) of dissolved solids decreased the analyte signals significantly. Internal standardization with Rh was efficiently used to compensate for these matrix effects. The accuracy of the method was verified using reference materials digested according to two different procedures: dry ashing and microwave digestion. No significant differences were observed between measured concentrations and certified values. The investigation was next extended for the determination of major elements [aluminum (Al), boron (B), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn)] on the same reference materials. The ICP‐MS values agree well with the values supplied. However, it appeared that Sc was the most useful internal standard for major elements.     

Release Rates of Ammonium‐Nitrogen,Nitrate‐Nitrogen,Phosphorus, Potassium,Magnesium, Iron,and Manganese from Seven Controlled‐Release Fertilizers

Abstract

Samples of seven controlled‐release fertilizers, Nutricote Total 13–13–13, Nutricote Total 18–6–8, Osmocote Plus 15–9–12, Osmocote 13–13–13, Polyon 18–6–12, Polyon 14–14–14, and Plantacote 14–8–15, were placed in leaching columns containing acid‐washed sand. Samples of all leachates were analyzed weekly to determine release rates of ammonium‐nitrogen (N), nitrate‐N, phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), and iron (Fe). Release rates for P from all products were slower than those for NH₄‐N, NO₃‐N, and K. Release of Mg, Mn, and Fe was very poor, with less than 50% of the total amount of each of these elements ever being released from the prills for some products. Nutricote products released Fe and Mn more effectively than did Osmocote or Plantacote.     

Evaluation of N2‐fixation measured by the 15N‐dilution and N‐difference methods in Nicaraguan and Ecuadorian Phaseolus vulgaris L. plants inoculated with Rhizobium leguminosarum biovar

Pot and field experiments were performed to assess N₂ fixation in Nicaraguan (R79 and R84) and Ecuadorian (Imba) common bean (Phaseolus vulgaris L.) cultivars, with the aim of improving their productivity by inoculating them with commercially produced Rhizobium phaseoli. With maize (Zea mays L.) as the non‐N₂‐fixing control, the percentage of N₂ fixed predicted by the ¹⁵N‐dilution method was significantly (P ≤ 0.05) higher than that predicted by the N‐difference method. However, the N₂ amounts predicted by the two methods were not significantly different. The correlation between the two methods was significant and positive (P ≤ 0.0001, n = 36). Compared with the native rhizobial strain, symbiotic associations of the bean cultivars with UMR1073, UMR1077 and UMR1899 rhizobial inoculants did not significantly (P ≤ 0.05) influence plant dry matter (DM) and N yields, the extent of N₂ fixation and uptake of soil and fertilizer N. Nevertheless, the UMR1077 and UMR1899 strains markedly increased the uptake of soil N by R84 plants, while decreasing N2 fixation. In contrast, the Imba‐UMR1899 association enhanced positive effects on all variables. About 60–70% of the total N taken up by the Imba plants was fixed N_2. The R79 and R84 plants fixed about 50% of their total N uptake. N₂ fixation rates were positively correlated with DM and total N yields, while being negatively correlated with soil N uptake (P ≤ 0.001, n = 36). Future research in Nicaragua should focus on selecting rhizobial strains suitable for indigenous common bean cultivars.     

Recovery of 15N‐Labeled Nitrate Injected into Deep Subsoil by Maize in a Calcareous Alluvial Soil on the North China Plain

Abstract

Recovery of residual nitrogen (N) from the subsoil by maize (Zea mays L.) was studied by injecting ¹⁵N‐labeled nitrate at 110 cm for treatments with and without N fertilizer in a calcareous soil on the North China Plain. The results show that the recovery of ¹⁵N‐labeled nitrate diffusing in the 90‐ to 130‐cm soil horizon was 11.9% with N fertilizer application and 6.7% without N application in maize. Nitrogen fertilizer applied to topsoil stimulated growth of maize roots in the subsoil, thus increasing the recovery of ¹⁵N‐labeled nitrate. In the relatively dry growing season in this experiment, the ¹⁵N‐labeled nitrate did not move downward because there was no downward water flow at 110 cm. Hence, under dry weather conditions, the maize crop can re‐utilize a small part of the residual soil nitrate in deep soil layers. Most of the nitrogen uptake was in the 0‐ to 80‐cm layer during the experiment.     

Comparison of New Ultrasonic Digestion Approaches for Plant Matrices in the Analysis of Trace Metals by Inductively Coupled Plasma–Optical Emission Spectroscopy Analysis: Contrast with USEPA Method 3050B

An ultrasonic method using two approaches, A and B, along with a reference Environmental Protection Agency (EPA) Method 3050B [i.e., a mixture of 30 mL of nitric acid–hydrochloric acid–hydrogen peroxide–water (HNO₃-HCl-H₂O₂-H₂O)] were contrasted for leaching of a plant matrix. The trace metals were arsenic, cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, selenium, and zinc (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se and Zn) and quantified by ICP-OES followed by an investigation into residue formation and the impact of digestion time. Approach B was the most accurate and precise with percent recoveries ranging between 99 and 120%, whereas ultrasonic approach A and the USEPA method 3050B gave similar results with poor accuracies and precisions. In the optimization of the digestion time using approach B, the total metal recovery was fairly the same over a period of 120 min except for Cr and Cu, which showed slight variations.     

Growth and nutrition of pansy as influenced by N‐form ratio and temperature

Abstract

Pansy (Viola xwittrockiana Gams.) producers often observe nutrient disorders among plants grown during warm periods (>18°C) of the growing season. These disorders typically are not seen when production temperatures are optimal (≥18°C) even though fertility regimes may remain the same. Our objectives were to assess the effects of temperature and nitrogen (N) fertility on growth and nutrition of pansy. Pansies cultivar ‘Crown White’ were grown until lateral branches had open flowers. Treatments consisted of two temperatures (12 and 22°C) and three NO₃ ^?:NH₄ ⁺ molar % ratios (100:0, 62:38, and 25:75) with a total concentration of 100 mg N L^?1. A modified Hoagland's solution was used with NO₃ ^?‐N supplied as Ca(NO₃)₂ and KNO₃ and with NH₄ ⁺‐N as (NH₄)₂SO₄. Cumulative nutrient absorption and foliar nutrient content were determined when plant lateral branches flowered. Root and shoot growth were limited when NH₄ ⁺ was present in solutions at high ambient air temperature (22°C), but not at low temperature (12°C). Individual absorption and accumulation of plant nutrients varied with N regimes and temperatures. Overall, pansies absorbed more total N, NH₄ ⁺, NO₃ ^?, calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P), zinc (Zn), and less iron (Fe) and manganese (Mn) at 12°C than at 22°C. In addition, absorption of NO₃ ^? by pansy was negligible if any NH₄ ⁺ was present in solutions at 22°C. Results suggest that pansy growers should adjust fertility programs according to production temperatures to avoid possible nutritional disorders and maximize plant growth. If maximum growth is to be obtained in warm temperatures, the use of NH₄ ⁺‐containing fertilizers should be reduced or eliminated. However, the choice of NO₃ ^?:NH₄ ⁺ ratio for nutrition may be less important under cool growing conditions.     

The use of the 15N‐dilution technique for field measurement of symbiotic nitrogen fixation

Abstract

Quantitative distribution of ¹⁵N in artificially and naturally enriched field‐growing legume‐based pastures are presented and compared. The results are discussed in terms of the assumption of the ¹⁵N‐dilution technique as a means of measuring symbiotic nitrogen fixation under field conditions.     

Short‐Term Recovery of Ammonium‐15Nitrogen Applied to a Temperate Forest Inceptisol and Ultisol in East Tennessee,USA

Abstract

The short‐term fate and retention of ammonium (NH₄)‐¹⁵nitrogen (N) applied to two types of forest soils in east Tennessee was investigated. Four ridgetop forests, predominantly oak (Quercus spp.), were studied. Five applications of NH₄‐¹⁵N tracer were made to the forest floor at 2‐ to 4‐week intervals over a 14‐week period in 2004. Nitrogen‐15 recovery in the forest floor, fine roots (<2 mm), and the mineral soil (0–20 cm) was calculated at 6, 21, and 42 weeks after the last application. Most of the ¹⁵N was retained in the forest floor and the mineral soil, with only small amounts (≤2%) found in roots from both soil layers. Recovery of NH₄‐¹⁵N was greater in Inceptisols, which had a wider carbon (C)‐to‐N ratio than Ultisols. For both soil types, higher NH₄‐¹⁵N recoveries and long retention times (half‐lives>100 weeks) indicated the forest floor is an effective filter for atmospheric N inputs.     

Depth and Width of the Wetted Zone in a Sandy Soil after Leaching Drip‐Irrigation Events and Implications for Nitrate‐Load Calculation

Abstract

The quantitative assessment of nitrate‐nitrogen (NO₃‐N) leaching below the root zone of vegetable crops grown with plasticulture (called load) may be done using 150‐cm‐deep soil samples divided into five 30‐cm‐long subsamples. The load is then calculated by multiplying the NO₃‐N concentration in each subsample by the volume of soil (width×length×depth, W×L×D) wetted by the drip tape. Length (total L of mulched bed per unit surface) and D (length of the soil subsample) are well known, but W is not. To determine W at different depths, two dye tests were conducted on a 7‐m‐deep Lakeland fine sand using standard 71‐cm‐wide plasticulture beds. Dye tests consisted of irrigation lengths of up to 38 and 60 h, digging transverse sections of the raised beds at set times, and taking measurements of D and W in 30‐cm‐deep increments. Most dye patterns were elliptically elongated. Maximum average depths were similar (118 and 119 cm) for both tests despite differences in irrigation duration and physical proximity of both tests (100 m apart in the same field). Overall, D response (cm, both tests combined) to irrigation volume (V, L/100 m) was quadratic (D_comb.avg=?2×10^?7 V²+0.008 V+34), and W responses (using maximum and mean values at each 30‐cm increment depth, W_max and W_mean, respectively) to D (cm) were linear (W_max=?0.65D+114 and W_mean=?0.42D+79). Predicted W_max were 104, 84, 64, 44, and 25 cm in 30‐cm depth increments. Load calculations using NO₃‐N concentrations of 7.2, 5.0, 3.9, 3.0, and 2.9 µg/kg for the 15, 46, 77, 107, and 137 cm depths, respectively, were 21.2, 37.6, 28.2, and 39.1 kg/ha for W values of 40 cm, bed width (71 cm), W_mean, and W_max, respectively. These load calculations ranged from simple to double based on the choice of W estimate used, which illustrates the importance of knowing W accurately when load is calculated from field measurements. These W_max and W_mean values may be used for load calculations on sandy soils but are likely to overestimate load because they were determined without transpiring plants and may need to be adjusted for different soil types.     

Distillation solution with and without indicator for nitrogen‐15 measurement by optical emission spectrometry

Abstract

Optical emission spectroscopy provides a rapid and precise method for determining ¹⁵N/¹⁴N ratios of ¹⁵N‐enriched plant and/or soil samples. The objective of this study was to determine the effect of an indicator added in the distillation solution on the success rate of tube lighting in the optical emission spectrometer over a large range of N concentration in ¹⁵N enriched plant samples. One‐hundred‐eighty plant samples with large ranges of N concentration (4 to 30 g.kg^‐1 dry weight) and ¹⁵N atom enrichment (0.368 to 1.635%) were analyzed. Our data suggest that there was no difference in the success rate of tube lighting in emission spectroscopy and in ¹⁵N/¹⁴N ratio measured between samples prepared with and without addition of indicator in the distillation solution.     

Potential of phenylphosphorodiamidate and N‐(N‐butyl) thiophosphoric triamide for inhibiting urea hydrolysis in simulated oxidized and reduced soils

Abstract

A laboratory study was conducted to assess the effectiveness of phenylphosphorodiamidate (PPD) and N‐(n‐butyl) thiophosphoric triamide (NBT) in retarding urea hydrolysis in four flooded rice soils under simulated oxidized and reduced conditions. Urea (400 μg N g^‐1soil) with PPD or NBT (2.0% w/w) was added to preincubated soils and analyzed for urea content 1, 3, 5, 7 and 15 days after N application. N‐(n‐butyl) thiophosphoric triamide was more effective in delaying urea hydrolysis under oxidizing conditions and at 5 days 57% of the added urea remained in the oxidized soils compared to only 4% under reduced soil conditions. In three soils, PPD was observed to be effective under reducing soil constraints. At 5 days 56 and 31% of the added urea was unhydrolyzed under reducing and oxidizing soil conditions, respectively, with the addition of PPD. For two soils 48% of the added urea remained at the 15 day sampling for the urea + NBT treatment     

The foliar absorption of urea‐N by tall fescue and creeping bentgrass turf

The absorption and assimilation of ¹⁵N‐labeled urea applied to the foliage of tall fescue (Festuca arundinacea Schreb.) and creeping bentgrass (Agrostis palustris Huds.) turf was examined under a controlled environment. Each source of N was dissolved in deionized water to a final concentration of 25 g N liter^‐1 and spray‐applied at a rate of 5 g N m^‐2. Absorption of the fertilizer‐N over a 72 hr period, as measured by ¹⁵N analysis of tissue digests, averaged 55% for the two species. Absorption was also estimated by a washing procedure which measured the urea remaining on the foliage, and by the increase in total N in the plant tissue.

There were no significant differences between the three methods in estimating absorption. Partitioning of the absorbed ¹⁵n between tissues averaged 37% in new leaves, 51% in old leaves and shoot tissue, and 11% in the roots. More than 90% of the absorbed urea‐N was hydrolyzed by 72 hr.     

Analysis of iron‐deficiency induced hydrogen release by plant roots using chemical equilibrium and pH‐stat methods

Iron (Fe) is an essential nutrient for plants. When Fe‐deficient, most dicotyledonous and non‐graminaceous monocotyledonous plants exhibit Fe‐deficiency stress responses, which may include proton (H⁺) release from roots. Proton release is considered to be one of the factors contributing to plant Fe‐deficiency resistance. Several methods, including the pH‐stat, back‐titration, and pH‐drift procedures, have been used to evaluate the Fe‐deficiency induced acidification process. These methods actually determine total net acidity release, not H⁺ release. A method, based on the principles of chemical equilibrium, for the analysis of net free H⁺ release is introduced in this paper. By comparing results of the chemical equilibrium method with those of a method measuring total net acidity release, such as the back‐titration method, it is possible to determine the relative role of free H⁺ and organic acid to total acidity release. The pH‐stat method for analysis of total net acidity release, in which the pH of the incubation solution is held constant, eliminates the influence of pH decrease during plant incubation and thus results in a more accurate measurement of Fe‐deficiency induced acidity release. The advantages and disadvantages of each individual method are discussed.     

Analysis of both cobalt and selenium in feed‐stuffs and in biological tissue by chelation‐extraction and graphite furnace atomic absorption spectroscopy

Abstract

A procedure for measuring cobalt in feedstuffs and biological tissues using ammonium pyrrolidine dithiocarbamate (APDC) and methyl isobutyl ketone (MIBK) chelation‐extraction and graphite furnace atomic absorption spectroscopy is described. This procedure, except for the graphite furnace and spectrophotometer programs, is identical to another method for analysis of selenium in the same types of sample materials. Therefore, only one chelation‐extraction is now required to measure both cobalt and selenium in the same sample. No evidence was seen of interference from other metals in the sample materials used in this study.     

Comparative Evaluation of Inductively Coupled Plasma–Optical Emission Spectroscopy and Atomic Absorption Spectrophotometry for Determining DTPA-Extractable Micronutrients in Soils

A study was conducted for comparative evaluation of atomic absorption spectrophotometry (AAS) and inductively coupled plasma–optical emission spectroscopy (ICP-OES) for determining extractable zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) in sixty diverse soil samples having a wide range in pH and organic carbon (C). The results were significantly affected by the method of analysis and soil type but generally did not follow a definite trend. Results for extractable Fe in Alfisol samples were significantly greater when using ICP-OES than AAS; and the results for Zn, Cu, and Mn were not significantly different for the two methods. For Vertisol samples, the results for extractable Cu were significantly greater by ICP-OES than by AAS, whereas extractable Fe and Zn were significantly greater by AAS than by ICP-OES, and the results for Mn were not significantly different for the two methods. The results are discussed relative to soil type and differences in soil organic carbon and pH of the samples used in the study.     

Recovery of 15N labelled ammonium nitrate by flue‐cured tobacco growing on a sandy loam

Abstract

An experiment was conducted to investigate the possible leaching of fertiliser N in flue‐cured tobacco growing on a sandy loam with two irrigation treatments using ^I5N as a tracer. No significant difference in ¹⁵N accumulation in the tobacco plant could be detected between the two irrigation treatments, recommended and conventional. Minimal soil leaching of the ^I5N was observed for both treatments at 60–90 cm depth. In four of the six experimental plots, recoveries were approximately 100% of the ¹⁵N applied, with 70% of the ¹⁵N being accumulated by the tobacco plant.     

Spectrophotometric and Inductively Coupled Plasma–Optical Emission Spectroscopy Determination of Gallium in Natural Soils and Soils Polluted by Industry: Relationships between Elements

The aim of this work was to determine gallium contents in different soils of Poland using a sensitive spectrophotometric method based on the complex of Ga(III) with chrome azurol S and benzyldodecyldimethylammonium bromide and inductively coupled plasma–optical emission spectrometry technique. The total content of gallium in the soils clearly depends on the soil location and properties and ranged from 41.7 to 437 μg g^–1. The contents of gallium determined in 10% nitric acid and 1 M of magnesium chloride extract ranges respectively from 38.0 to 81.9% and 20–40% of the total content of this element. A strong correlation has been found between gallium and zinc, cadmium, lead, and copper. The high Pearson correlation coefficient values and the proportional relationship between the concentrations of Ga and these metals may make it possible to treat gallium as an indicator of soil contamination with heavy metals.