Influence of nitrate and chloride on the adsorption and transport of sulphate in soils

The adsorption and desorption of SO₄ was investigated as a function of KCI and KNO₃ concentration using soils with contrasting surface-charge properties. In the net negatively-charged soils, additions of C1 or NO₃ of up to about 0.05–0.10 M increased the adsorption of SO₄ but at higher concentrations adsorption decreased. In contrast, adsorption by the net positively-charged soils decreased with concentration increase over the entire range (0 to 1 M) investigated. The effects of CI and NO₃ on the adsorption of SO₄ were practically identical. The different pattern of SO₄ adsorption in the two groups of soils in response to addition of KCI or KNO₃ can at least partly be explained in terms of the effect of electrolyte on soil pH. The depression in pH of net negatively-charged soils induced by an indifferent electrolyte favours adsorption of SO₄; but, because pH changes in the opposite direction in positively-charged soils, SO₄ adsorption decreases in these soils. The distribution of a pulse of 35S-labelled SO₄ in soil columns after leaching with KCI solutions, ranging in concentration from 0 (H₂O) to 0.10 M, clearly reflected the manner in which electrolyte concentration affected the adsorption of SO₄. The distribution of ³⁵S was reasonably well simulated using the general transport equation combined with the Freundlich equation to describe the adsorption/desorption of SO₄. In contrast to other inorganic anions (H₂PO₄ and OH) applied in agricultural practice, C1 and NO₃ may have beneficial effects on the S economy of many soils by decreasing leaching losses of SO₄.     

Simultaneous automated determination of chloride,nitrite, nitrate,and ammonia in water and wastewater

An automated system capable of simultaneous determination of chloride, nitrite, nitrate, and ammonia in about 2 ml of fresh water or wastewater is described. The four compounds are determined using modifications of established colorimetric procedures. Results can be reported at a true rate of five samples per hour with a relative standard deviation at optimum concentrations of less than 2%. Detection limits are 1 ppm Cl for chloride and 1, 5, and 5 ppb N for nitrite, nitrate, and ammonia, respectively. Sample pH adjustment is not required from 0.0002 N H₂SO₄ (pH 3.7) to 0.005 N NaOH (pH 11.2). Fresh water and wastewater samples were analyzed for nitrite and ammonia by the proposed procedure and by the manual sulfanilic-naphthylamine and nesslerization method. Analysis by the student t-test showed no significant difference between the paired sets of data (P > 0.5). When potable and wastewater samples were spiked with sodium chloride, potassium nitrate, sodium nitrite, and ammonium chloride and analyzed, average recoveries were 99 to 103%.     

Comparative rates of leaching of chloride, nitrate and tritiated water under field conditions

The rate of leaching of 36Cl-, 15NO-3 and HTO were measured in two experiments under field conditions following the application of irrigation water (40mm and 80 mm) and under winter rainfall (71 mm and 156 mm excess over evaporation). Nitrate and chloride leached at about the same rate, which was on average 23 per cent faster than that of HTO, but with a smaller difference under winter rainfall. It is concluded that although HTO is not an accurate marker for nitrate leaching, ‘bomb’ tritium gives a rough guide to the dating of nitrate pulses in porous rock.     

The effect of chloride and sulphate salts on the nitrate content in lettuce plants (Lactuca sativa L.)

The effect of chloride and sulphate on the nitrate accumulated in lettuce plants (Lactuca sativa L., cv. deci minor) under low light conditions was examined. The plants were grown on a complete nutrient solution for circa 45 days and then chloride was substituted for the nitrate in the nutrient solution. In another experiment, sulphate was substituted for the nitrate in the nutrient solution. Approximately 5 days later a reduction in growth occurred. The nitrate in the plants was not completely exhausted and was very slowly available for reduction both in the leaf blades and midribs. It was immaterial whether sulphate or chloride was substituted for nitrate in the nutrient solution. Chloride was taken up from the solution but sulphate was not. In plants in both treatments, sugars accumulated concomitantly with the decrease in nitrate content.

The actual nitrate reductase activity in the leaf blades decreased several days after the chloride and sulphate treatments began and was negligible on day 12. Nevertheless, the potential nitrate reductase activity of the treated plants was still 50% of the control.

It is suggested that the availability of nitrate from the storage pool is the limiting process for nitrate reductase activity, and is independent of the metabolic demand. For commercial growers it may be of advantage to use hydroponics in which the nitrate can be removed easily several days before harvest, to reduce high nitrate contents in vegetables, particularly under low light conditions.     

Influence of added ammonium sulphate on the leaching of aluminium,nitrate and sulphate —A laboratory experiment

Relationships between the concentrations of sulphate, nitrate and Al were studied in leachates from reconstructed soil profiles of a previously N fertilized Haplic Podzol. Half of the profiles were covered with the grassDeschampsia fexuosa (Trin.), and the other half were not. The soil profiles were subjected to different N loads, in the form of ammonium sulphate. The doses were 0.5 mmol ammonium-N during the first part of the experiment and 1.0 mmol ammonium-N during the later part. Uptake of N by the vegetation almost completely eliminated the effects of added ammonium, even when the soil profile was strongly nitrifying. Fertilizer treatment caused nitrate to leach from the non-covered soil profiles, although there was a net retention of N. The concentration of Al in leachates was positively correlated with nitrate. Fertilizer treatment increased the proportion of inorganic monomeric Al in leachates. Most sulphate retention seemed to take place in the O horizon. In the presence of vegetation sulphate concentration was enhanced to a greater degree than could be explained from differences in evapotranspiration estimated from the Cl^?/S0₄ ^2? ratio in the leachates. Soil N dynamics on a forest clear-cutting are discussed with reference to the present findings.     

Effects of chloride and partial substitution of reduced forms of nitrogen for nitrate in nutrient solution on the nitrate,total nitrogen,and chloride contents of onion

An experiment was conducted to determine the effects of chloride (Cl) and reduced forms of nitrogen (N) on the nitrate (NO₃), total N, and Cl concentrations in onion (Allium cepa L.) plants using a non‐recirculating nutrient film growing system. The reference treatment was a nutrient solution containing 19 mM NO₃ and 1.25 mM ammonium (NH₄). The results from this treatment were compared with that obtained using mixed amino acid, urea, and glycine treatments with or without additional Cl (10 mM) in which 20% of the NO₃ in the reference treatment was substituted with one of these reduced forms of N. Fresh and dry weights of the onion plants were not affected by the treatments. The NO₃ content was considerably lower in the mixed amino acid treatment, being 4236 mg NO₃/kg FW as compared to either the reference, urea, or glycine treatments. The NO₃ contents of the plants in these treatments were 5393, 5339, and 5261 mg NO₃/kg FW, respectively. The presence of Cl in the nutrient solution also reduced the NO₃ content of the plants from 5816 to 4299 mg NO₃/kg FW. The reduced‐N treatments increased the total N contents of the plants. The Cl content of the plants was increased by the Cl supplied and by the reduced forms of N in the nutrient solution.     

Diffusion of coefficients of carbon dioxide, nitrous oxide, ethylene and ethane in air and their measurement

Binary diffusion coefficients were measured by a steady-state method in which a gas was introduced at a constant rate into one end of a tube through which it moved by mass flow and diffusion into a semi-infinite volume of air. The Stefan correction for mass flow was modified to allow for initial gas concentrations < 100 per cent, conferring four advantages: errors in the total flow rate are relatively unimportant; density gradients are small so that convection is inhibited; the gas analysis is more sensitive; and diffusion coefficients are measured at the small concentrations that are encountered in soils. Measured diffusion coefficients (cm² s^?1 at NTP) in air for carbon dioxide (0.139), nitrous oxide (0.143), ethylene (0.137) and ethane (0.128) are compared with measured and calculated values from other sources.     

Potassium,nitrogen, ammonium/nitrate ratio,and sodium chloride effects on wheat growth

Fertigation with KNO₃ as a means of reducing salinity hazards was tested with peanut (Arachis hypogaea) plants grown on dune sand, resulting in a reduction of plant growth and yield. The objective of this work was to study the interactions between N, K⁺ and NaCl as well as the effects of the NH₄ ⁺/NO₃ ^‐ ratio on vegetative and reproductive growth. Wheat (Triticum aestivum L.) plants were grown in polyethylene pots with fine calcareous dune sand with different proportions of NH₄ ⁺ and NO₃ ^‐, under saline (60 mM NaCl) and non‐saline conditions. Three replicates were harvested at the beginning of flowering, and one was grown to grain maturity. NaCl reduced shoot dry weight in all the treatments. Increasing the NH₄ ⁺ proportion in the total of 6 mM N in the nutrient solution, increased shoot dry weight, did not change nitrogen concentration in the dry mass but increased P percentage, either with or without 60 mM NaCl. The number of tillers produced in each treatment was correlated with dry matter yield. The effect of the NH₄ ⁺/NO₃ ^‐ ratio may be explained by alteration of the cation‐anion balance on the nutrient uptake by roots, which lowered pH of the nutrient solution with increasing NH₄ ⁺ concentration, by alteration of the cation‐anion balance on the nutrient uptake by roots, which lowered pH of the nutrient solution with increasing NH₄ ⁺ concentration.     

外源氯处理对向日葵幼苗生长、养分吸收及植株硝态氮含量的影响

通过水培试验,研究了不同水平外源氯处理对向日葵(Helianthus.annuus)幼苗生长、干物质积累、Cl-、NO3-、全N、全P、全K含量的影响。结果表明,不同浓度外源氯(Cl-6.253～00.mmol/L)处理8.d,油葵幼苗的茎生长速率均显著下降,外源Cl-浓度越大,生长下降越显著。Cl-6.252～5.mmol/L处理8.d,油葵幼苗干物质积累速率极显著高于对照,Cl-25、50.mmol/L处理,油葵幼苗的干物质积累速率与对照差异不显著;而Cl-2003～00.mmol/L处理的幼苗干物质积累极显著下降。Cl-处理下,植株体内氯含量极显著上升,而叶片中硝酸盐含量显著下降,其中以Cl-50.mmol/L处理的叶片硝酸盐含量最低。Cl-6.251～00.mmol/L处理,油葵幼苗茎、叶全N、全P含量与对照差异不显著;Cl-200.mmol/L处理下,叶、茎全N含量显著下降,而根系全N、全P含量随Cl-处理的增加而增加。随着Cl-浓度处理的提高,油葵幼苗根、茎、叶的全K含量增加,其中以根、茎增加较快。因此,一定范围的外源氯处理,不影响向日葵生物量甚至促进生物量积累的同时,也可明显的提高向日葵幼苗的氮素利用效率。     

A130 years deposition record of sulfate,nitrate and chloride from a high-alpine glacier

An ice core from a high-alpine glacier (Grenzgletscher, Colle Gnifetti, Monte Rosa massif, 4450 m a.s.l., Switzerland) was used to reconstruct the pollution history of Central-Europe. Concentrations of the most important acidifying species sulfate and nitrate as well as of chloride were measured in 1151 samples with 5 cm resolution from the top 60 m of a 109 m long firn/ice core. This corresponds to a mean time resolution of 8 (bottom) to 14 (top) data points per year. A ²¹⁰Pb nuclear dating showed that the ice core covers a time period between 1850–1981 and that the mean accumulation rate was 0.33 m water equivalent per year. Between the two time periods 1850 – 1880 and 1965 – 1981 the mean sulfate concentrations increased by a factor of 5.8±0.9 and for nitrate by a factor of 2.3±0.3. The mean concentrations at the beginning of the industrial time (period 1850 –1880) was 0.078±0.008 mg/l for sulfate and 0.067±0.005 mg/l for nitrate. The mean chloride concentration was 0.047±0.004 mg/l and did not show a trend in concentration over the time period investigated. A distribution analysis of the measured concentrations for the two time periods 1850 – 1865 and 1965 – 1981 was performed which showed that the data have a nearly log-normal distribution.     

Influence of ammonium,nitrate, and chloride on solution pH and ion uptake by ageratum and salvia in hydroponic culture

The influence of nitrogen (N) forms and chloride (Cl) on solution pH and ion uptake in the hydroponic culture of Ageratum houstonianum [ammonium (NH₄ ⁺)‐tolerant] and Salvia splendens (NH₄ ⁺‐sensitive) for a period of 216 hours was investigated. The pH of the hydroponic solution (initially 6.50) containing either NH₄ ⁺ or NH₄ ⁺+nitrate (NO₃ ^‐) was drastically lowered (3.08), whereas that of the same solution containing NO₃ ^‐ was raised (7.74). Solution pH changed more by ageratum than by salvia. The solution Cl^‐ concentration did not influence pH significantly. However, addition of Cl^‐ in the solution lowered transpiration rate in both NH₄ ⁺ and NO₃ ^‐ treatments. Total N uptake was the greatest in the NH₄ ⁺ + NO₃ ^‐ treatment and the lowest in the NO₃ ^‐treatment. In the NH₄ ⁺ + NO₃ ^‐ treatment, NO₃ ^‐ uptake was suppressed by NH₄ ⁺ (to about 50%), while NH₄ ⁺ uptake was not affected by NO₃ ^‐. The rate of Cl^‐ uptake was the lowest in the NH₄ ⁺ treatment, but was similar in the NH₄ ⁺ + NO₃ ^‐ and NO₃ ^‐ treatments. Uptake of potassium (K⁺), dihydrogen phosphate (H₂PO₄ ^‐), sulfate (SO₄ ^‐2), manganese (Mn⁺²), and zinc (Zn⁺²) was significantly enhanced in the NH₄ ⁺ treatment. The uptake rate of calcium (Ca⁺²) and magnesium (Mg⁺²) was the highest in the NO₃ ^‐ treatment. Absorption of copper (Cu⁺²) and boron (B) was not affected by N source. Ion uptake was more stable in the solution containing both NH₄ ⁺ and NO₃ ^‐ than in the solution containing either NH₄ ⁺ or NO₃ ^‐. The uptake rate of total N, NH₄ ⁺, NO₃ ^‐, Mn⁺², Cu⁺², and Zn⁺² was higher, whereas that of Cl^‐ and molybdenum (Mo) was lower in ageratum than in salvia. Amounts of total anion (TA) and total cation (TC) absorbed, the sum of TC and TA, and the difference between TC and TA (TC‐TA) were affected by N source, Cl^‐ level, and their interactions. The NO₃ treatment, as compared to the NH₄ ⁺ or the NH₄ ⁺ + NO₃ ^‐treatment, reduced total cation and anion uptake while increasing TC‐TA, especially in the absence of Cl^‐. Plant tissue ion contents were also affected by N source and Cl^‐ level.     

Ammonia volatilization from ammonium sulphate,ammonium nitrate,and urea surface applied to winter wheat on a calcareous soil

Abstract

Ammonia (NH₃) volatilization losses from surface‐applied ammonium sulphate (AS), ammonium nitrate (AN), and urea to winter wheat and the effects of the NBPT [N‐(n‐butyl) thiophosphoric triamide], PG (Phospho‐gypsum), and PR (byproduct‐Pyrite) were determined in a field experiment. Effects on grain yield and protein content of the grain were also measured. Total NH₃ losses from AS, AN, and urea varied from 13.6–19.5%, 4.4–6.4%, and 3.9–12.0% depending on the compounds and their levels added to nitrogen (N) fertilizers, respectively. The compounds added to AS and AN increased NH₃‐N losses with respect to unamended fertilizers (control). On the other hand, while urea treatments with two tons of PG/ha increased NH₃ losses, the other compounds decreased the losses. The highest reductions of NH₃ loss were observed with NBPT 0.50% and NBPT 0.25% by 63.4% and 52.8%, respectively. Although the effect of nitrogeneous fertilizers on total N losses and protein content of wheat grain was found statistically significant (p<0.01), as the compounds applied with N fertilizers have had no significant effect. Also, a negative and highly significant correlation (r = ‐0.69???) was found between total N loss and protein content of the grain.     

The spatial and temporal variation of the sulphate to nitrate ratio in precipitation in eastern North America

Four years of precipitation chemistry data for eastern North America were used to investigate seasonal and geographical variations in \({\text{SO}}_{\text{4}}^{\text{ = }} {\text{/NO}}_{\text{3}}^{\text{ - }} \) ratio. Several distinct regimes occur. One, in the region of heaviest acidic deposition extending from the states south of the Great Lakes across New England and southeastern Canada, has a very strong seasonal variation in the \({\text{SO}}_{\text{4}}^{\text{ = }} {\text{/NO}}_{\text{3}}^{\text{ - }} \) molar ratio in deposition. The ratio ranges from about 1.5 in summer to about 0.5 in winter. Another, in the smaller area of Texas and surrounding states, shows the reverse seasonal pattern. Yet another, in the high plains states, has a double maximum in the ratio in Spring and Fall. The remainder of the region has an irregular seasonal pattern. Insight into the cause of \({\text{SO}}_{\text{4}}^{\text{ = }} {\text{/NO}}_{\text{3}}^{\text{ - }} \) variations was obtained using a simple chemical transport box model. It showed that the chemical transformation of S0₂ and NO_x in the atmosphere is a major factor. A comparison of model predictions and observations indicate that in the vicinity of mid-western American sources the molar ratio of amount of S0₂ oxidized in-cloud to that of N0₂ is O.5 in winter and 1.5 in summer.     

Development and testing of a model for predicting tillage effects on nitrate leaching from cracked clay soils

Both water movement and nitrate leaching in structured soils are strongly influenced by the nature of the macro-porosity. That macro-porosity can however also be manipulated by choice of tillage operations. In order to investigate the potential impacts of tillage on rates of nitrate leaching from structured soils, a model specific to these soils, CRACK-NP was developed. The model, its application and validation for an experimental site on a heavy clay soil (Verti-Eutric Gleysoil) at Brimstone Farm, Oxfordshire, UK, is described. The model considers the soil as a series of aggregates whose size is also the spacing of the macro-porosity. Water and solutes move in the macro-pores, but within the peds they move only by diffusion, internal infiltration and root uptake (evaporation). The model reflects the influence of diffusion limitation in the release of solutes to by-passing water. The model was then used to investigate the influence of variable ped spacings which were created by variations in tillage practices. The results both from the model and from the field data demonstrated that finer soil structures, which have larger surface contact areas and shorter diffusion path lengths, present greater opportunities for interaction between peds and the water moving around them, and so release more nitrates through the drainage waters.     

氯离子在土壤中的扩散: Ⅱ.动力学及热力学性质

The amounts of chloride ions diffused in four soils of different textures at the same water content under different temperature and at varied time were measured by the diffusion cell method using ³⁶Cl-labelled CaCl₂ solution. Five kinetic models were used to fit the dynamic process of the diffusion of chloride ions in the soils. It was found that Elovich equation or power function equation was the best model to describe the process. The pseudothermodynamic parameters, i.e. the net reaction energy, the activation entropy, activation enthalpy and activation free energy of the diffusion, were derived from the absolute reaction-rate theory. The results showed that these parameters decreased in the order of loessal soil > black lu soil > lou soil > yellow cinnamon soil, which indicated that the force and the heat-energy barrier to be overcome for diffusion decreased, the diffusion rate increased and the disorder of the soil-solution-ion system due to diffusion decreased successively with the texture becoming heavier in the four soils.     

过量施用氯离子的扩散: I. 土壤湿度、容重及温度的影响

Diffusion coefficients of chlorde ions in four soils of different exture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm^3 under three different temperatures were determined by the diffusion-cell method using ^36Cl-labelled CaCl2 solution.The result showed that activation energy decreased with water content,which indicated that the threshold fro diffusion was lower at a higher soil moisture rate .Therefor,the diffusion coefficient(D) of chloride ions in soil increased consistently with soil moisture,Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed,the increase rate in different soils was not the same.The D value increased with teperature,and with temperature increased by 10℃ in the range from 5℃to 45℃ the D valve increased by 10%-30%,averaging about 20%.     

Extraction of mobile element fractions in forest soils using ammonium nitrate and ammonium chloride

The extraction of earth alkaline and alkali metals (Ca, Mg, K, Na), heavy metals (Mn, Fe, Cu, Zn, Cd, Pb) and Al by 1 M NH₄NO₃ and 0.5 M NH₄Cl was compared for soil samples (texture: silt loam, clay loam) with a wide range of pH(CaCl₂) and organic carbon (OC) from a forest area in W Germany. For each of these elements, close and highly significant correlations could be observed between the results from both methods in organic and mineral soil horizons. The contents of the base cations were almost convertible one‐to‐one. However, for all heavy metals NH₄Cl extracted clearly larger amounts, which was mainly due to their tendency to form soluble chloro complexes with chloride ions from the NH₄Cl solution. This tendency is very distinct in the case of Cd, Pb, and Fe, but also influences the results of Mn and Zn. In the case of Cd and Mn, and to a lower degree also in the case of Pb, Fe, and Zn, the effect of the chloro complexes shows a significant pH dependency. Especially for Cd, but also for Pb, Fe, Mn, Zn, the agreement between both methods increased, when pH(CaCl₂) values and/or contents of OC were taken into account. In comparison to NH₄Cl, NH₄NO₃ proved to be chemically less reactive and, thus, more suitable for the extraction of comparable fractions of mobile heavy metals. Since both methods lead to similar and closely correlated results with regard to base cations and Al, the use of NH₄NO₃ is also recommended for the extraction of mobile/exchangeable alkali, earth alkaline, and Al ions in soils and for the estimation of their contribution to the effective cation‐exchange capacity (CEC). Consequently, we suggest to determine the mobile/exchangeable fraction of all elements using the NH₄NO₃ method. However, the applicability of the NH₄NO₃ method to other soils still needs to be investigated.     

生物炭对黄土区土壤水分入渗、蒸发及硝态氮淋溶的影响

为了揭示生物炭对黄土区不同质地土壤水分入渗、蒸发特性及硝态氮淋溶的影响规律及差异,该研究选取黄土区3种典型土壤(风沙土、黄绵土和黑垆土),设置质量分数0、0.5%、1%、2%、3%和5%共6个比例的生物炭梯度,进行室内土柱模拟试验。结果表明:湿润锋进程与累积入渗量受生物炭添加量及土壤质地的影响。随着生物炭添加量的增大,风沙土和黑垆土的水分入渗速度和累积入渗量逐渐降低(P0.05);黄绵土水分入渗和累积入渗量呈先增大后减缓的趋势(P0.05)。生物炭未显著影响试验条件下黄绵土和黑垆土的累积蒸发量(30 d),但显著改变了风沙土的蒸发特征,抑制前期蒸发。不同生物炭添加量下,3种土壤的湿润锋运移距离与运移时间均符合幂函数关系;Philip入渗模型可描述添加生物炭土壤水分入渗变化过程。生物炭可减少黄土区3种质地土壤的硝态氮淋溶量,表明适量生物炭添加能够增强土壤氮素固持能力,降低硝态氮淋失及环境风险。该研究结果表明,生物炭作为一种土壤改良剂能够提高土壤持水性和降低硝态氮淋失,有利于黄土高原旱地作物的生长;同时该研究可为农田选择合理生物炭施用量提供科学参考。     

磷酸二氢钙和氯化钾对氯化铵处理黄泥土水溶性铵态氮和硝态氮的影响

氮磷钾是农业生产中大量施用并且经常共同施用的肥料,三者在土壤中的相互作用对养分的迁移转化、吸收和代谢有着深远影响.本文模拟生产中氮磷钾肥料同施,研究了田间持水量条件下磷酸二氢钙、氯化钾对氯化铵处理土壤水溶性铵态氮和硝态氮的影响.结果表明,铵态氮施入土壤后,随着培养时间的延长,土壤中水溶性铵态氮含量下降,硝态氮含量升高,两者之间存在着显著相关性.磷酸二氢钙延缓了铵态氮向其他形态氮的转变,使培养中期土壤水溶性铵态氮显著高于氯化铵处理土壤,并对培养中后期硝态氮的增加有抑制作用.氯化钾增加了培养前中期氯化铵处理土壤铵态含量,但显著抑制了氯化铵处理土壤培养后期硝态氮的含量.因此,农业生产中氯化铵和氯化钾共施,氯化铵和磷酸二氢钙共施,氯化铵、氯化钾和磷酸二氢钙共施,对提高氮肥利用率,降低硝态氮淋失损失均有重要作用.