Influence of the Modification of Nutritional Parameters in Aglaonema commutatum: K+, Ca2+, Mg2+ and Na+

Abstract

This trial was carried out to establish an appropriate nutrient solution for Aglaonema commutatum and to investigate the nutritional effects generated by modifications in the solution. Six treatments were tested: control (T₀; pH 6.5, E.C. 1.5 dS m^?1, 6 mmol L^?1 NO₃ ^?‐N, and 6 mmol L^?1 K⁺); high nitrogen (N) level (T₁; 9 mmol L^?1 6:3 NO₃ ^?–NH₄ ⁺); N form (T₂; 6 mmol L^?1 N‐NH₄ ⁺); high K⁺ level (T₃; 12 mmol L^?1 K⁺); high electrical conductivity (T₄; E.C. 4 dS m^?1, 25 mmol L^?1 NaCl), and basic pH (T₅; pH 8). At the end of the cultivation, leaf, shoot, and root dry weights and elemental concentrations were determined. Nutrient contents and total plant uptake were calculated from the dry weights and nutrient concentrations. Plant K⁺ uptake increased with application of K⁺ or basic nutrient solution. The uptake and transport of calcium (Ca) were enhanced by the use of NO₃ ^?‐N and inhibited by the presence of other cations in the medium (NH₄ ⁺, K⁺, Na⁺) and by basic pH. Magnesium (Mg) uptake increased with NO₃ ^?‐N application and with pH. Sodium (Na) uptake was the highest in the saline treatment (T₄), followed by the basic pH treatment. Sodium accumulation was detected in the roots (natrophobic plant), where the plant generated a physiological barrier to avoid damage. Dry weight did not differ significantly (p<0.05) among treatments except in the NaCl treatment. These results may help in the formulation of nutrient solutions that take into account the ionic composition of irrigation water and the physiological requirements of plants.     

Adsorption of the insecticidal protein of Bacillus thuringiensis subsp. kurstaki by minerals: effects of inorganic salts

The persistence of the insecticidal protein of Bacillus thuringiensis (Bt) is enhanced by the reactivity with soil particles and may constitute a hazard to the soil ecosystem; however, studies on the fate of the Bt toxin in soil, especially in the presence of inorganic salts, are limited. The effects of different concentrations of KNO₃, KH₂PO₄ and NH₄H₂PO₄ on the adsorption of Bacillus thuringiensis toxin by kaolinite, montmorillonite, goethite and silicon dioxide were investigated. Results showed that small salt concentrations tended to enhance toxin adsorption, whereas large concentrations (> 10 mmol litre^?1) inhibited sorption. Similar results were observed regardless of the order in which toxin and inorganic salt were added. The degree to which individual salts affected adsorption decreased in the sequence for minerals, goethite > kaolinite ≥ montmorillonite > silicon dioxide, and for ions, H₂PO₄^? > NO₃^?, NH₄⁺ > K⁺. Our results indicate that inorganic salts can markedly influence the adsorption of Bt toxin by soil minerals. This investigation will help in evaluating the behaviour and fate of Bt toxins in the soil environment.     

Comparing Two Extraction Methods to Evaluate the Composition of Substrate Solution of a Burnt Rice Husk Substrate Used for Carnation Crops

Substrates have been increasingly used in recent years for carnation crops. Burnt rice husk (BRH) is widely available and used as a substrate in Colombia. The present work aims to compare the effects of two aqueous extraction methods on the chemical contents. Saturated and 1:1 (v/v) extractions were performed in three replications. Ionic forms of the macronutrients (NO₃^?, NH₄⁺, PO₄H₂^?, K⁺, Ca²⁺, Mg²⁺, and SO₄^2?, in meq L^?1), micronutrients (Fe, Mn, Zn, Cu, and B, in mg L^?1), Cl^?, CO₃ H^? in meq L^?1, electrical conductivity in dS m^?1, and pH were analyzed. Except for NH₄⁺, Cl^?, and B the determination coefficient R² was greater than 95 percent. Average values and standard errors of data have been used to define suitable intervals for 1:1 extractions. Proposed intervals for 1:1 extracts are consistent with the saturated extract and therefore are a good tool to optimize the management of fertigation in those crops.     

Comparative Study of the Leachates from Syngonium podophyllum using Different Fertilization Techniques and Nitrogen Forms

The objectives of this article were to analyze the evolution of the nutrient parameters of the leachates collected from Syngonium podophyllum var. Silver plants cultivated for 20 weeks in a buried greenhouse with four methods of fertilization. The treatments were T₁, standard liquid feeding (SLF) [7.0 mmol L^?1 nitrate (NO₃ ^?) nitrogen (N), 0.3 mmol L^?1 phosphorus (P), and 3.5 mmol L^?1 potassium (K)] after transplanting; T₂, liquid feeding soluble fertilizer (LFSF) [6.9% NO₃ ^? N, 11.1% ammonium (NH₄ ⁺) N stabilized by 3,4-dimethylpyrazole phosphate, 8.0% P₂O₅, and 14.0% K₂O] after transplanting; T₃, controlled release fertilizer (CRF I) (7.4% NO₃ ^? N, 8.6% NH₄ ⁺ N, 8.0% P₂O₅, and 12.0% K₂O) applied before planting and half concentration of SLF from 45 days after transplanting; and T₄, controlled release fertilizer (CRF II) (8.5% NO₃ ^? N, 7.5% NH₄ ⁺ N, 8.0% P₂O₅, and 12.0% K₂O) applied before planting and half concentration of SLF from 45 days after transplanting. Solution pH, electrical conductivity (EC), NO₃ ^? N, NH₄ ⁺ N, K, and P concentrations in the leachate were analyzed weekly. Plant quality was assessed at the end of the trial through objective and subjective parameters. Significant differences among the different fertilization methods were observed. CRF treatments resulted in the greatest nutrient leachate concentration during the first 6 weeks of the study, and afterward it decreased gradually until the end of the cultivation. CRF I showed greater leachate concentrations of N, P, and K than the others during the first half of the study. The concentrations of NO₃ ^? N and P from all the fertilizer types were often above the permissible levels cited in the federal Clean Water Act. The best-quality plants were obtained with CRF II, whereas the greatest height and Aerial Dry Weight (ADW) were obtained with CRF treatments and the greatest Root Dry Weight (RDW) was obtained with the NH₄ ⁺ N treatments.     

Nitrogen Source and Concentration Affect Growth and Performance of Bedding-Plant Impatiens

ABSTRACT

Impatiens (Impatiens wallerana Hook. f.) is the most important annual bedding plant in the United States, based on wholesale dollar volume. Production of high-quality plants requires optimization of the nutrition regimen during growth, especially the total nitrogen (N) concentration and the ratio of N sources. The objective was to determine the N concentration and the nitrate (NO₃ ^??N):ammonium (NH₄ ⁺?N) ratio of N source that optimized bedding-plant impatiens growth and flower development. Four N concentrations (3.5, 7, 10.5, and 14 mmol N · L^?1) were used in factorial combination with four ratios of NO₃ ^??N:NH₄ ⁺?N (4:0, 3:1, 1:1, and 1:3). Application of treatments was made for 30 d. Then for 10 d only deionized water was applied to reduce salt buildup. Substrate pH was lowest (4.9) with the NH₄ ⁺?N source and electrical conductivity (EC) highest, but never > 2.4 dS m^?1. Nitrogen concentration and N source displayed an interaction for most growth parameters. Shoot fresh and dry weights and flower bud number were maximized at the 1:3 NO₃ ^??N:NH₄ ⁺?N ratio with a N concentration of 10.5 mmol L^?1. However, plant diameter, leaf number, and leaf chlorophyll content responded quadratically to N form ratio, with the 1:1 ratio optimum at a concentration of 10.5 mmol N· L^?1.     

Diurnal Macronutrients Uptake Patterns by Lettuce Roots under Various Light and Temperature Levels

In order to reduce nutrient wastes to the environment the supply should be in accordance to the demand for these. Two experiments were conducted to study and quantify the effect of temperature, irradiance, and plant age on the uptake of nitrate (NO₃^?), ammonium (NH₄⁺), dihydrogen phosphate ion (H₂PO₄^?), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), and sulfate (SO₄²). In the first experiment, various levels of temperature and irradiance were applied to plants in a growth chamber, while in the second experiment the uptake was studied along the crop season under greenhouse conditions. The uptake rates were calculated at 2-hour intervals through sampling the nutrient solution and analyzing it by inductively coupled plasma atomic emission spectrometry (ICP-AES). Increasing light and temperature enhance the uptake rates, while the rates decrease with plant age. Nitrogen absorption was similar during the day as during the night. No differences were found in the absorption of H₂PO₄^?, K⁺, Ca²⁺, Mg²⁺, and SO₄^2? between day and night. Nitrate absorption was found to have a positive correlation with the absorption of all the ions except for NH₄⁺.     

Evalution of Acid Deposition in Korea

This study was carried out to evaluate acid depositions and to understand their effect. Wet precipitation has been collected at twenty-four sites in Korea for one year of 1999. The ion concentrations such as H⁺, Na⁺, K⁺, Mg²⁺, NH₄ ⁺, Ca²⁺, Cl^?, NO₃ ^? and SO₄ ^2? were chemically analyzed and determined. Precipitation had wide range of pH(3.5～8.5), and volume-weighted average was 5.2. The contribution amounts of Cl^?, SO₄ ^2? and NO₃ ^? in anion were shown to be 54%, 32%, and 14%, respectively and those of Na⁺ and NH₄ ⁺ in cation were 32% and 25%. The ratios of Cl^? and Mg²⁺ to Na⁺ in precipitation were similar to those of seawater, which imply that great amount of Cl^? and Mg²⁺ in precipitation could be originated from seawater. The concentration of H⁺ is little related with SO₄ ^2?, NO₃ ^? and Cl^? ions, whereas nss^?SO₄ ^2? and NO₃ ^? are highly correlated with NH₄ ⁺, which could suggest that great amount of SO₄ ^2? and NO₃ ^? exist in the form of ammonium associated salt. The annual wet deposition amounts (g m^?2year^?1) of SO₄ ^2?, NO₃ ^?, Cl^?, H⁺, NH₄ ⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺ were estimated as 0.88～4.89, 0.49～4.37, 0.30～9.80, 0.001～0.031, 0.06～2.15, 0.27～4.27, 0.10～3.81, 0.23～1.59 and 0.03～0.63.     

Spatio-temporal variations in nutrient concentration in soil solution under greenhouse tomato

The aim of this trial was to study the spatio-temporal variability in solution nutrient concentration under intensive greenhouse tomato production, to determine the number of suction-cups needed to obtain a representative sample and the influence by the position in the greenhouses. Twenty sampling points were selected within the greenhouse with one suction-cup per sampling point. One soil solution were sampled per point at weekly intervals to analyze for pH, electrical conductivity, chloride, nitrate, phosphate, sulfate, sodium, potassium, calcium, and magnesium (EC, Cl^?, NO₃^?, H₂PO₄^?, SO₄^2—, Na⁺, K⁺, Ca²⁺, and Mg²⁺) concentrations. The pH, Cl^?, H₂PO₄^?, and SO₄^2? concentrations showed no spatio-temporal variation but EC, NO₃^?, and K⁺ showed temporal variation. The spatial variability in EC, K⁺_, Na⁺, Mg²⁺, and Ca²⁺ can be influenced by microclimate and topography. The numbers of suction cups required for a representative sample ranged from 1 to 10 depending on nutrient.     

Daily macronutrient uptake patterns in relation to plant age in hydroponic lettuce

A greenhouse experiment was conducted to study and quantify the daily uptake rate of nitrate, ammonium, phosphoric acid, potassium, calcium, magnesium, and sulfate (NO₃^?, NH₄⁺, H₂PO₄^?, K⁺, Ca²⁺, Mg²⁺ and SO₄^2?) and to characterize the uptake daily pattern at different plant ages in a lettuce crop. The uptake rates per gram of plant fresh weight were calculated at 2-hour intervals through sampling the nutrient solution and analyzing it by NO₃^?/NH₄⁺ conductivity and inductively coupled plasma atomic emission spectrometry (ICP-AES). The uptake rate of nitrogen, phosphorus and potassium (N, P and K) per unit mass of plant decreased with plant age following a reduction in plant relative growth rate. No significant differences were found in the absorption of Ca, Mg and sulfur (S) between the different weeks of growth. The daily absorption patterns showed no preference for the absorption of any of the ions during the daytime. A significant reduction in the absorption peaks of all the ions with increasing plant age was observed.     

Characteristics of ammonium and nitrate fluxes along the roots of Picea asperata

Nitrogen (N), ammonium (NH₄⁺) and nitrate (NO₃^?), is one of the key determinants for plant growth. The interaction of both ions displays a significant effect on their uptake in some species. In the current study, net fluxes of NH₄⁺ and NO₃^? along the roots of Picea asperata were determined using a Non-invasive Micro-test Technology (NMT). Besides, we examined the interaction of NH₄⁺ and NO₃^? on the fluxes of both ions, and the plasma membrane (PM) H⁺-ATPases and nitrate reductase (NR) were taken into account as well. The results demonstrated that the maximal net NH₄⁺ and NO₃^? influxes were detected at 13–15?mm and 8–10.5?mm from the root apex, respectively. Net NH₄⁺ influx was significantly stimulated with the presence of NO₃^?, whereas NH₄⁺ exhibited a markedly negative effect on NO₃^? uptake in the roots of P. asperata. Also, our results indicated that PM H⁺-ATPases and NR play a key role in the control of N uptake.     

Sorption and Desorption Characteristics of Ion Exchange Resins to Estimate Leaching Losses in the Field

Laboratory experiments were conducted to determine sorption and desorption properties of ion exchange resins based on recovery rates. Dissolved nitrate (41.6 mM NO₃ ^? and 166.5 mM NO₃ ^?), ammonium (63.9 mM NH₄ ⁺ and 256.1 mM NH₄ ⁺), phosphate (3.5 mM PO₄ ^3– and 13.9 mM PO₄ ^3–), and potassium (16.11 mM K⁺ and 63.94 mM K⁺) were factorially combined and added at flow rates of 5 L at 3 and 9 h to an exchange resin?/?sand mixture. Six extractions with 1 M sodium chloride (NaCl) desorbed >90% of the added ions. Apparent recovery rates for nitrate (NO₃-N) averaged 99% (±6), for ammonium (NH₄-N) averaged 100% (±8), and for phosphate (PO₄-P) averaged 109% (±6). Apparent recovery rates of potassium (K) were erroneously high (151% ± 12) and largely reflected analytical interference problems with the inductively coupled plasma (ICP) method. Concentrations of dissolved ions did not affect recovery rates of any studied ion.     

Effects of Nitrate and Potassium on Ammonium Toxicity in Cucumber Plants

ABSTRACT

Interactions between nitrate (NO₃ ^?), potassium (K⁺), and ammonium (NH₄ ⁺) were investigated using hydroponically grown cucumber (Cucumis sativus L.) plants. Ammonium as the sole nitrogen (N) source at 10 mM was toxic and led to overall growth suppression, chlorosis, and necrosis of leaves. After 20 days, 50% of the plants were dead. However, when NO₃ ^? was supplied at very low concentration together with high NH₄ ⁺ (only 1% of total 10 mM N) all seedlings survived and their growth was improved. High K⁺ concentration (5 mM) also alleviated NH₄ ⁺ toxicity and increased plant growth several fold compared to intermediate concentration of K⁺ (0.6 mM). Leaf total N and ¹⁵N derived from ¹⁵N-labelled NH₄ ⁺ increased in the presence of NO₃ ^?, but decreased at high K⁺ concentration. High K⁺ supply enhanced total carbon (C) and δ ¹³C and stimulated GS and PEPCase activities in leaves and roots. Nitrate supplementation had no effect on GS or PEPCase activities. It is concluded that K⁺ may alleviate NH₄ ⁺ toxicity, partly by inhibiting NH₄ ⁺ uptake, partly by stimulating C and N assimilation in the roots.     

Comparison of Factors Affecting Soil Nitrate Nitrogen and Ammonium Nitrogen Extraction

Extraction of soil nitrate nitrogen (NO₃ ^?-N) and ammonium nitrogen (NH₄ ⁺-N) by chemical reagents and their determinations by continuous flow analysis were used to ascertain factors affecting analysis of soil mineral N. In this study, six factors affecting extraction of soil NO₃ ^?-N and NH₄ ⁺-N were investigated in 10 soils sampled from five arable fields in autumn and spring in northwestern China, with three replications for each soil sample. The six factors were air drying, sieve size (1, 3, and 5 mm), extracting solution [0.01 mol L^?1 calcium chloride (CaCl₂), 1 mol L^?1 potassium chloride (KCl), and 0.5 mol L^?1 potassium sulfate (K₂SO₄)] and concentration (0.5, 1, and 2 mol L^?1 KCl), solution-to-soil ratio (5:1, 10:1, and 20:1), shaking time (30, 60, and 120 min), storage time (2, 4, and 6 weeks), and storage temperature (?18 ^oC, 4 ^oC, and 25 ^oC) of extracted solution. The recovery of soil NO₃ ^?-N and NH₄ ⁺-N was also measured to compare the differences of three extracting reagents (CaCl₂, KCl, and K₂SO₄) for NO₃ ^?-N and NH₄ ⁺-N extraction. Air drying decreased NO₃ ^?-N but increased NH₄ ⁺-N concentration in soil. Soil passed through a 3-mm sieve and shaken for 60 min yielded greater NO₃ ^?-N and NH₄ ⁺-N concentrations compared to other treatments. The concentrations of extracted NO₃ ^?-N and NH₄ ⁺-N in soil were significantly (P < 0.05) affected by extracting reagents. KCl was found to be most suitable for NO₃ ^?-N and NH₄ ⁺-N extraction, as it had better recovery for soil mineral N extraction, which averaged 113.3% for NO₃ ^?-N and 94.9% for NH₄ ⁺-N. K₂SO₄ was not found suitable for NO₃ ^?-N extraction in soil, with an average recovery as high as 137.0%, and the average recovery of CaCl₂ was only 57.3% for NH₄ ⁺-N. For KCl, the concentration of extracting solution played an important role, and 0.5 mol L^?1 KCl could fully extract NO₃ ^?-N. A ratio of 10:1 of solution to soil was adequate for NO₃ ^?-N extraction, whereas the NH₄ ⁺-N concentration was almost doubled when the solution-to-soil ratio was increased from 5:1 to 20:1. Storage of extracted solution at ?18 °C, 4 °C, and 25 °C had no significant effect (P < 0.05) on NO₃ ^?-N concentration, whereas the NH₄ ⁺-N concentration varied greatly with storage temperature. Storing the extracted solution at ?18 ^oC obtained significantly (P < 0.05) similar results with that determined immediately for both NO₃ ^?-N and NH₄ ⁺-N concentrations. Compared with the immediate extraction, the averaged NO₃ ^?-N concentration significantly (P < 0.05) increased after storing 2, 4, and 6 weeks, respectively, whereas NH₄ ⁺-N varied in the two seasons. In conclusion, using fresh soil passed through a 3-mm sieve and extracted by 0.5 mol L^?1 KCl at a solution-to-soil ratio of 10:1 was suitable for extracting NO₃ ^?-N, whereas the concentration of extracted NH₄ ⁺-N varied with KCl concentration and increased with increasing solution-to-soil ratio. The findings also suggest that shaking for 60 min and immediate determination or storage of soil extract at ?18 ^oC could improve the reliability of NO₃ ^?-N and NH₄ ⁺-N results.     

The inherent 'safety-net' of an Acrisol: measuring and modelling retarded leaching of mineral nitrogen

The inherent features of Acrisols with their increasing clay content with depth are conducive to reducing nutrient losses by nutrient adsorption on the matrix soil surfaces. Ammonium (NH₄⁺) and nitrate (NO₃^?) adsorption by a Plinthic Acrisol from Lampung, Indonesia was studied in column experiments. The peak of the H₂¹⁸O breakthrough occurred at 1 pore volume, whereas the median pore volumes for NH₄⁺ and NO₃^? ranged from 6.4 to 6.9 and 1.1 to 1.6, respectively. The adsorption coefficients (K_a in cm³ g^–1) measured were 1.81, 1.51, 1.64 and 1.47 for NH₄⁺ and 0.03, 0.09, 0.10 and 0.17 for NO₃^?, respectively, in the 0–0.2, 0.2–0.4, 0.4–0.6 and 0.6–0.8 m soil depth layers. The NH₄⁺ and NO₃^? adsorption coefficients derived from this study were put in to the Water, Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model to evaluate their effect on leaching in the context of several cropping systems in the humid tropics. The resulting simulations indicate that the inherent ‘safety‐net’ (retardation mechanism) of a shallow (0.8–1 m) Plinthic Acrisol can reduce the leaching of mineral N by between 5 and 33% (or up to 2.1 g m^?2), mainly due to the NH₄⁺ retardation factor, and that the effectiveness in reducing N leaching increases with increasing depth. However, the inherent ‘safety‐net’ is useful only if deep‐rooted plants can recover the N subsequently.     

GROWTH AND NUTRITION OF YOUNG BEAN PLANTS UNDER HIGH ALKALINITY AS AFFECTED BY MIXTURES OF AMMONIUM,POTASSIUM, AND SODIUM

High concentrations of bicarbonate (HCO^? ₃) cause alkalinity of irrigation water and are associated with suppression in plant growth and micronutrient deficiencies, such as iron (Fe) and zinc (Zn). Because reports indicate that the deleterious effects of alkalinity may be counteracted partially by supplementary potassium (K⁺) or ammonium (NH₄ ⁺) an experiment was designed to evaluate the response of bean plants (Phaseolus vulgaris L.) grown in high alkalinity conditions to varying proportions of NH₄ ⁺, K⁺, or sodium (Na⁺) (as a potential substitute for K⁺). Plants established in a growth chamber were grown in hydroponics for 21 days in solutions containing 5 mM HCO^? ₃ and a total of 5 mM of a mixture of NH₄ ⁺, K⁺, and Na⁺. The proportions of NH₄ ⁺, K⁺, and Na⁺ were designed according to mixture experiment methodology. Total N in all the mixture treatments was maintained at 10 mM by using nitrate (NO^? ₃)-N, thus the NH₄ ⁺:NO^? ₃ ratio varied according to the proportion of NH₄ ⁺ in the mixtures. Alkalinity caused suppression in plant growth and chlorophyll concentration in the younger leaves, whereas excessive NH₄ ⁺ was associated with leaf scorching and decreased leaf expansion. High proportions of K⁺ alleviated alkalinity symptoms and produced higher shoot and root dry mass provided that NH₄ ⁺ was included in the mixture. However, a proportion of NH₄ ⁺ higher than 0.333 in the mixture (>1.66 mM NH₄ ⁺) induced toxicity. The highest shoot dry mass occurred if the NH₄ ⁺:NO^? ₃ ratio was 0.19:0.81 and the NH₄ ⁺:K⁺:Na⁺ proportion was 0.38:0.38:0.24 (1.9 mM NH₄ ⁺ + 1.9 mM K⁺ + 1.2 mM Na⁺). Thus, an improvement in plant growth is achieved when NH₄ ⁺, K⁺, and Na⁺ are blended together, in spite of the high alkalinity treatment imposed. Optimum NH₄ ⁺ was associated with a decrease in solution pH and an increase in shoot Fe and Zn concentration.     

Influence of Ammonium and Nitrate Nutrition on Plant Growth and Zinc Accumulation by Indian Mustard

ABSTRACT

The source of nitrogen (N) used in soil fertility practices affects plant growth, nutrient absorption, and the availability of nutrients. Consequently, the potential of plants to extract zinc (Zn) from soils may be increased by controlling the ratio of NH₄ ⁺ to NO₃ ^? to maximize growth and Zn accumulation. The objectives of this research were to determine the effects of Zn supply and different molar ratios of NH₄ ⁺ to NO₃ ^? on growth and Zn accumulation in Indian mustard (Brassica juncea Czern.). In a factorial experiment with solution culture, Indian mustard (accession 182921) was supplied with two concentrations of Zn (0.05 and 4.0 mg L^?1) in combination with six N treatments with different molar percentage ratios of NH₄ ⁺ to NO₃ ^? (0:100, 10:90, 20:80, 30:70, 40:60, and 50:50) for three weeks. Zinc supplied at 0.05 mg Zn L^?1 represented a common concentration of Zn in solution culture, whereas 4.0 mg Zn L^?1 was excessive for plant nutrition. If the supply of Zn in solution was excessive, plants developed symptoms of foliar chlorosis, which became severe if plants were supplied with 80% of N as NO₃ ^?. Supplying high proportions of NO₃ ^? in the nutrient medium stimulated Zn accumulation, whereas increasing proportions of NH₄ ⁺ (up to 50% of the total N) enhanced shoot growth. The pH of nutrient solutions generally decreased with increasing proportion of NH₄ ⁺ in solutions and with increased Zn supply. The Zn phytoextraction potential of Indian mustard was maximized, at about 15 mg Zn plant^?1, if plants received 10% of the total N as NH₄ ⁺ and 90% as NO₃ ^?.     

Influence of potassium:rubidium ratios on the xylematic transport of solutes in cucumber plants grown with nitrate plus ammonium

The influence of three potassium:rubidium (K:Rb) ratios (6:0, 5:1, and 4:2) on the xylematic transport of solutes in cucumber plants cv. Medusa supplied with both nitrate (NO₃ ^‐) (60%) and ammonium (NH₄ ⁺) (40%) was studied in greenhouse conditions. In the xylem sap of plants grown with a K:Rb ratio of 4:2, there was an increase in the transport of NO₃ ^‐, phosphate (H₂PO₄ ^‐), calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), manganese (Mn) and boron (B) while that of organic‐N, organic‐P, K⁺, zinc (Zn), organic acids, and carbohydrates decreased, if compared with the sap of the plants supplied with K alone. The translocation of NO₃ ^‐, H₂PO₄ ^‐, Ca²⁺, Mg²⁺, and Mn was enhanced and that of K⁺ and organic acids decreased when the plants were supplied with a K:Rb ratio of 5:1. The K:Rb ratio detected in the xylem sap was the same K:Rb ratio as in the solutions. However, in the cucumber plant substituting 33% of total K by Rb resulted in an alteration in the transport of solutes, probably due to a competition between Rb and K rather than between the latter two and NH₄ ⁺.     

Chemical Composition of Precipitation, Throughfall and Soil Solutions at Two Forested Sites in Guangzhou, South China

Rain water at two forested sites in Guangzhou (south China) show high concentrations of SO₄ ^2?, NO₃ ^? and Ca²⁺ and display a remarkable seasonal variation, with acid rain being more important during the spring and summer than during the autumn and winter. The amount of acid rain represents about 95% of total precipitation. The sources of pollutants from which acid rain developed includes both locally derived and long-middle distance transferred atmosphere pollutants. The seasonal variation in precipitation chemistry was largely related to the increasing neutralizing capacity of base cations in rainwater in winter. Soil acidification is highlighted by high H⁺ and Al³⁺ concentrations in soil solutions. The variation in elemental concentration in soil solution was related to nitrification (H⁺, NH₄ ⁺ and NO₃ ^?) and cation exchange reaction (H⁺, Al³⁺) in soil. The negative effect of soil acidification is partly dampened by substantial deposition of base cations (Ca²⁺, Mg²⁺ and K⁺) in this area.     

Source Identification of Rural Precipitation Chemistry in Japan

Precipitation chemistry was discussed from the viewpoint of potential sources for four rural sites where wet-only daily-basis measurement data sets were available during the period from April 1996 to March 1997 in Japan. Annual volume-weighted mean concentrations of nss-SO₄ ^2? and NO₃ ^? ranged from 18.0 to 34.6 µeq L^?1, and from 9.3 to 23.1 µeq L^?1, respectively. The degree of neutralization of input acidity in terms of the concentration ratio, [H⁺] / ([nss-SO₄ ^2?] + [NO₃ ^?]), ranged from 0.46 to 0.63. This suggests that about half of the input acidity due to H₂SO₄ and HNO₃ was neutralized by NH₄ ⁺ and nss-Ca²⁺ to produce the pH values of 4.46 to 4.82 for these sites. Maximum likelihood factor analysis was then performed on the logarithmically transformed daily wet deposition of major ions. Two factors successfully explained a total of about 80% of the variance in the data for each site. Interpreting varimax rotated factor loadings, we could identify two source types: (1) acid source with large loadings on ln(H⁺), ln(nss-SO₄ ^2?), ln(NO₃ ^?) and ln(NH₄ ⁺), (2) sea-salt source with large loadings on ln(Na⁺), ln(Cl^?), ln(Mg²⁺) and ln(K⁺). The rural wet deposition over Japan appears to have a similar structure in terms of the kinds of sources and their relative location.     

NH4+-K+ co-loaded clinoptilolite as a binary fertilizer

ABSTRACT

Understanding the potential of clinoptilolite (CLI) for adsorption of NH₄⁺ and K⁺, providing appropriate fertilizer formula, and evaluation of the produced zeolitic nutrient sources (ZNSs) to meet the plant need are the main objectives of this study. Three ZNSs (NH₄⁺-saturated, K⁺-saturated and dual-purpose NH₄⁺-K⁺ saturated CLI) were produced, assessed, and compared with commercial N and K fertilizers (CFs) on corn growth in a greenhouse. The results indicated that CLI can potentially adsorb both NH₄⁺ and K⁺ to the maximum values of 25.00 mg-NH₄⁺ g^?1 and 47.61 mg-K g^?1, respectively, and chemisorptions mainly followed the process of adsorption. Saturation of zeolite by NH₄⁺ and K⁺ occurred after 10 and 15 d which lead to ZNSs with 2% and 5% of N and K, respectively. NH₄⁺-K⁺ saturated CLI contained 1% N and 1% K. The greenhouse experiment showed no significant difference between ZNSs and CFs on plant growth. However, the application of both N and K in the form of zeolitic sources significantly increased the uptake of N by the plant. The highest uptake of K (2.05 g pot^?1) occurred in plants supplied with both natural zeolite and CFs. The present results may benefit the future utilization of ZNSs in environmental friendly farming practices.