铁铝氢氧化物对两种土壤和高岭石表面K+和NH4+解吸的影响

Potassium (K) and nitrogen (N) are essential nutrients for plants. Adsorption and desorption in soils affect K+ and NH + 4 availabilities to plants and can be affected by the interaction between the electrical double layers on oppositely charged particles because the interaction can decrease the surface charge density of the particles by neutralization of positive and negative charges. We studied the effect of iron (Fe)/aluminum (Al) hydroxides on desorption of K+ and NH + 4 from soils and kaolinite and proposed desorption mechanisms based on the overlapping of diffuse layers between negatively charged soils and mineral particles and the positively charged Fe/Al hydroxide particles. Our results indicated that the overlapping of diffuse layers of electrical double layers between positively charged Fe/Al hydroxides, as amorphous Al(OH) 3 or Fe(OH) 3 , and negatively charged surfaces from an Ultisol, an Alfisol, and a kaolinite standard caused the effective negative surface charge density on the soils and kaolinite to become less negative. Thus the adsorption affinity of these negatively charged surfaces for K+ and NH + 4 declined as a result of the incorporation of the Fe/Al hydroxides. Consequently, the release of exchangeable K+ and NH +4 from the surfaces of the soils and kaolinite increased with the amount of the Fe/Al hydroxides added. The greater the positive charge on the surfaces of Fe/Al hydroxides, the stronger was the interactive effect between the hydroxides and soils or kaolinite, and thus the more release of K+ and NH + 4 . A decrease in pH led to increased positive surface charge on the Fe/Al hydroxides and enhanced interactive effects between the hydroxides and soils/kaolinite. As a result, more K+ and NH + 4 were desorbed from the soils and kaolinite. This study suggests that the interaction between oppositely charged particles of variable charge soils can enhance the mobility of K+ and NH + 4 in the soils and thus increase their leaching loss.     

Evidence that fungi can oxidize NH4+ to NO3− in a grassland soil

The contribution of bacteria and fungi to NH₄⁺ and organic N (N_org) oxidation was determined in a grassland soil (pH 6.3) by using the general bacterial inhibitor streptomycin or the fungal inhibitor cycloheximide in a laboratory incubation study at 20°C. Each inhibitor was applied at a rate of 3 mg g^?1 oven‐dry soil. The size and enrichment of the mineral N pools from differentially (NH₄¹⁵NO₃ and ¹⁵NH₄NO₃) and doubly labelled (¹⁵NH₄¹⁵NO₃) NH₄NO₃ were measured at 3, 6, 12, 24, 48, 72, 96 and 120 hours after N addition. Labelled N was applied to each treatment, to supply NH₄⁺‐N and NO₃^?‐N at 3.15 μmol N g^?1 oven‐dry soil. The N treatments were enriched to 60 atom % excess in ¹⁵N and acetate was added at 100 μmol C g^?1 oven‐dry soil, to provide a readily available carbon source. The oxidation rates of NH₄⁺ and N_org were analysed separately for each inhibitor treatment with a ¹⁵N tracing model. In the absence of inhibitors, the rates of NH₄⁺ oxidation and organic N oxidation were 0.0045 μmol N g^?1 hour^?1 and 0.0023 μmol N g^?1 hour^?1, respectively. Streptomycin had no effect on nitrification but cycloheximide inhibited the oxidation of NH₄⁺ by 89% and the oxidation of organic N by more than 30%. The current study provides evidence to suggest that nitrification in grassland soil is carried out by fungi and that they can simultaneously oxidize NH₄⁺ and organic N.     

Kinetics of nonexchangeable‐potassium release and plant response in some calcareous soils

Nonexchangeable K⁺ constitutes a slowly available reserve that may significantly influence K⁺ fertility of soils. Laboratory and greenhouse experiments were conducted to characterize the K⁺ supply and nonexchangeable K⁺–release kinetics in 10 calcareous soils using 0.01 M CaCl₂ and 0.01 M oxalic acid extractions. Total K⁺ uptake by wheat (Triticum aestivum L.) grown in the greenhouse was used to measure plant‐available K⁺. The release of K⁺ was characterized by an initial fast rate followed by a slower rate. The nonlinear relationship in the early stages of the K⁺ release may be attributed to the edge sites, and release of K⁺ from interlayer exchange sites may be responsible for the second part of the K⁺ release. Kinetics of K⁺ release was described best with power function, which showed the best fit of the four models tested. Parameters of kinetics models in 0.01 M CaCl₂ were significantly related to K⁺ uptake by wheat. Potassium release was also correlated to initial NH₄OAc‐extratable K⁺ and to HNO₃‐extractable K⁺.     

不同铵钾比对高铵下拟南芥地上部和根系生长的影响

钾在缓解植物铵毒害的过程中起着重要的作用。本文研究了高铵(30 mmol/L)条件下,不同铵钾比(7.5︰1和150︰1)对拟南芥(Col-0)主根、侧根以及地上部生长的影响。结果表明:30 mmol/L NH4+条件下,高铵钾比(150)处理显著加重了拟南芥铵毒害现象,地上部和根系生长所受的抑制作用更为明显并导致更严重的氧化胁迫。相比低铵钾比水平,在高铵处理下,高铵钾比使得拟南芥主根伸长量降低57.4%,侧根数量减少33.3%,而地上部鲜重减轻69.9%。DAB(3,3￠-二氨基联苯胺,3,3￠-diaminobenzidine)叶片染色结果表明,不加铵处理下,外源不同钾水平(0.2和4.0 mmol/L)对拟南芥叶片的氧化胁迫作用没有显著差异;而高铵处理下,相比低铵钾比处理,高铵钾比显著增加了叶片中过氧化氢的含量,加重了其氧化胁迫。伊文思蓝(Evans blue,EB)染色结果表明,不加铵处理下,外源不同钾水平对拟南芥地上部和根部的膜透性没有显著差异,而高铵处理下,高铵钾比显著增强了拟南芥地上部和根部的膜透性,表明其对细胞的伤害程度加重。可见,高铵抑制拟南芥根系和地上部生长,高铵钾比则会加重这种抑制,其原因除了高浓度钾能减少植物对铵的吸收外,可能与高铵钾比条件加剧了植物的氧化胁迫有关。因此,适宜的铵钾比在植物应对铵毒害的过程中发挥重要作用。     

A modified Kjeldahl procedure for determining strongly fixed NH4+-N

This paper reports a procedure for determining the content of strongly fixed NH₄⁺ in soil. The procedure consists of a Kjeldahl digestion followed by an acid attack of the residue with a 5 m HF:1 m HCl solution. Distillations after each of the two treatments recover different forms of NH₄⁺. The procedure was tested on fine earth (< 2 mm) and skeleton (> 2 mm) fractions of two forest soils developed on sandstone parent material. In both soil fractions we evaluated three different forms of NH₄⁺-N: (i) Kjeldahl, (ii) non-exchangeable and (iii) micaceous. The last is located in the interlayer of mica flakes larger than 50 μm that resist the Kjeldahl digestion and is considered strongly fixed. The total NH₄⁺-N content of a soil is obtained by the summation of the Kjeldahl and the micaceous NH₄⁺-N. In the soils under consideration, the micaceous form prevails in the skeleton because this fraction is richer in micas of sand size (> 50 μm). Following the proposed procedure, we found that micas (muscovite and biotite) contain about 3000 mg kg^–1 of NH₄⁺-N in the interlayer. The presence of micaceous NH₄⁺-N in soil is generally ignored because the skeleton is usually excluded from analyses, and the micas larger than 50 μm cannot be dissolved by the Kjeldahl treatments. The micaceous NH₄⁺ is the least extractable form of NH₄⁺-N, and we infer that it is the least available to plants.     

THERMODYNAMICS AND THERMOCHEMISTRY OF THE EXCHANGE REACTION BETWEEN NH4+ AND Mn2+ IN A MONTMORILLONITE CLAY

The exchange reaction between NH₄⁺ and Mn³⁺ was studied on a montmorillonite clay at several temperatures and different ionic strengths. Manganese was preferred to ammonium; this preference increased with the temperature and dilution of the dialysate. Comparison with published data concerning exchanges involving NH₄⁺ and the alkaline-earths showed that in the sequence of increasing selectivity: Mg²⁺ < Ca²⁺ < Sr²⁺ < Ba²⁺, Mn²+ lies between Mg²⁺ and Ca²⁺. The enthalpy change was measured calorimetrically and calculated by application of the van't Hoff law to the temperature coefficient of the equilibrium constants. Both values were in good agreement. The excellent recoveries of Mn²⁺ at the end of the exchange reaction and the constancy of the cation exchange capacity over the whole range of surface composition ruled out the possibility of significant adsorption in the MnOH⁺ form. The behaviour of manganese was very similar to that of the alkaline-earth cations.     

The influence of increased NH4+ deposition rates on aluminium chemistry in the percolate of acid soils

The influence of different NH₄⁺ loads on aluminium speciation in percolating water was studied on acid luvisols with similar soil-pH values but with different soil adsorption surface characteristics. All of the applied NH₄⁺ was nitrified and therefore led to proton production. Thus, Al displacement in the percolate was increased. The extent of this enhanced translocation was found to be chiefly a function of the amount of exchangeable base cations which buffered the protons produced by nitrification. The proportion of the different Al species in the percolate was altered at large NH₄⁺ loads. Very large A1³⁺ concentrations eliminated Al species bound to dissolved organic matter and particles, presumably because of flocculation and precipitation of organic ligands. Furthermore, increased NO₃^? and A1³⁺ concentrations enhanced the desorption of F^? giving rise to an additional increase in Al displacement by the formation of Al fluoro complexes in the aqueous phase.     

TRANSFORMATION OF 15N-LABELLED AMMONIUM IN TWO SOILS DIFFERING IN NH+4-FIXING CAPACITY

Two soils differing in ammonium fixation capacity were incubated for 127 days with ¹⁵N-ammonium sulphate. In a gley soil with high NH⁺₄-fixing capacity caused by smectites with a charge up to 0.8 per formula unit, the major part of the added ammonium was first fixed by minerals and then released slowly during incubation. The proportion of labelled N in the nitrate fraction increased during the first weeks and then decreased permanently. In contrast, in a histosol with low NH⁺₄-fixing capacity, the exchangeable fraction contained most of the labelled NH⁺₄, this being highly available to microorganisms and therefore subject to nitrification. About 50% of the added ¹⁵NH₄ was lost from the histosol in 127 days, but only about 20 per cent was lost from the gley soil.     

Interactions of aluminium and fulvic acid in moderately acid solutions: stoichiometry of the H+/Al3+ exchange

Complexation with organic matter controls the activity of dissolved Al³⁺ in many soils. The buffering intensity of these soils is largely dependent on the H⁺/Al³⁺ exchange ratio, i.e. the number of protons consumed by the solid phase when one Al³⁺ is released. Here, the H⁺/Al³⁺ exchange ratio was determined from batch titrations using solutions of fulvic acid (FA) as a model for soil organic matter. Aluminium was added, from 1.04 to 6.29 mmol Al per g FA, which is within the range of humus‐bound Al found in the upper B horizon of podzolized soils. Furthermore, pH was varied with NaOH to give values between 3.5 and 5.0. The H⁺/Al³⁺ exchange ratio ranged between 1.49 and 2.23 with a mean of 1.94. It correlated positively with pH and the total concentration of Al present. Theoretically, this can be explained with a partial hydrolysis of bound Al. The slope of logAl (log₁₀ of Al³⁺ activity) against pH generally underestimated the actual exchange ratio, which can partly be attributed to the systems being diluted (100 mg FA l^?1). However, where 4 mmol Al or more had been added per g FA, the logAl slope gradually approached ?3 between pH 4.5 and 5.0. This might be the result of a shift from Al³⁺ activity control by humus complexation to control by Al(OH)₃(s).     

Fixed ammonium and potassium release from two soils

Abstract

Release of native and added K⁺ and NH⁺ ₄ from two soils was monitored during a 166 day incubation/leaching experiment. One soil (Brookston) represented a major soil series In Ontario whereas the other (Harriston) was suspected having a relatively large fixation capacity. Treatments were imposed involving addition of 50 μM g^‐1 soil of K⁺(KCl) or NH⁺ ₄ (NH₄Cl) only or one added after the other on successive days. The addition of either K⁺ or NH⁺ ₄ on day 2 tended to inhibit the release of the other added on day I. Also the addition of either K⁺ or NH⁺ ₄ on day 1 tended to inhibit the sorption or fixation of the other on day 2. The release rate of K⁺ during the 10 to 166 day period was almost constant and not affected by the addition of NH⁺ ₄. Alternatively, the addition of K⁺ on day 2 slowed the release rate of NH⁺ ₄ measured by NO^? ₃ appearance from day 10 to 40 but had no effect thereafter. At the end of the experiment considerably more K⁺ than NH⁺ ₄ was retained suggesting that K⁺ was more firmly fixed. However, the continuing nitrification of NH⁺ ₄ must be contrasted with periodic removal of K⁺ by leaching with 0.01 M CaCl₂ solution since the equilibrium between exchangeable and fixed ions was affected. There were no notable differences between the two soils inspite of a considerable difference in clay content.     

聚天门冬氨酸钙盐对水稻田面水中三氮动态变化的影响

利用桶栽试验探究不同浓度水平的聚天门冬氨酸钙盐(PASP-Ca)对水稻田面水中铵态氮(NH_4~+)、硝态氮(NO_3~-)和总氮(TN)浓度动态变化的影响。结果表明,施氮后,田面水中TN、NH_4~+和NO_3~-分别于第1,3,9天达到最大值,随后逐渐降低。NO_3~-/TN多在0.1以下,(NH_4~++NO_3~-)/TN多在0.5以上。因此,可以将NH_4~+和TN作为农田水污染防治的主要监测指标,NO_3~-作为辅助指标。添加一定浓度的PASP—Ca能对田面水中氮素浓度的变化起到缓释作用,其中0.3%浓度水平的PASP—Ca效果相对较好,田面水中NH_4~+和TN的下降速率分别为3.452,4.806mg/(L·d),与单施氮肥(CK)相比,分别降低了11.68%和16.25%;同时,NH_4~+的平均浓度为6.999mg/L,较CK低了3.88%;NO_3~-的平均浓度为0.396mg/L,较CK低了24.83%;TN的平均浓度为20.077mg/L,较CK提升了3.10%。施氮后田面水中TN浓度随时间呈对数递减,而NH_4~+浓度在施氮后3天内随时间呈对数增加,之后随时间呈对数递减趋势。施氮后的9天内是防止稻田田面水中氮素流失的关键时期。     

Aluminium release in relation to the determination of cation exchange capacity of some podzolized New Zealand soils

In upper mineral horizons, CEC by compulsive and isotopic exchange methods, using Ba²⁺ as the saturating cation, gave higher values than the effective CEC at natural soil pH, and much higher values than CEC determined with m NH₄OAc at pH 7. Cumulative Al release during leaching was considerably higher using Mg²⁺ and Ba²⁺ chlorides than K⁺ and NH₄⁺ chlorides, and gave a different shape extraction curve. Basal spacing of the dominant dioctahedral vermiculite in the soil clays contracted from 14.5Å to 10.0–10.9 Å when saturated with NH₄⁺ and K⁺, restricting release of interlayer Al. Lower horizons, containing a large proportion of Al-chlorite in the clay fraction, which did not contract with any of the cations, showed more normal exchange behaviour. On leaching, Al release was slightly greater with K⁺ and NH₄⁺, than with Mg²⁺ and Ba²⁺, chlorides. The implication of the results for CEC measurements is discussed.     

Simulating the dynamics of glucose and NH4+ in alkaline saline soils of the former Lake Texcoco with the Detran model

The turnover of organic matter determines the availability of plant nutrients in unfertilized soils, and this applies particularly to the alkaline saline soil of the former Lake Texcoco in Mexico. We investigated the effects of alkalinity and salinity on dynamics of organic material and inorganic N added to the soil. Glucose labelled with ¹⁴C was added to soil of the former Lake Texcoco drained for different lengths of time, and dynamics of ¹⁴C, C and N were investigated with the Detran model. Soil was sampled from an undrained plot and from three drained for 1, 5 and 8 years, amended with 1000 mg ¹⁴C‐labelled glucose kg^?1 and 200 mg NH₄⁺‐N kg^?1, and incubated aerobically. Production of ¹⁴CO₂ and CO₂, dynamics of NH₄⁺, NO₂^– and NO₃^–, and microbial biomass ¹⁴C, C and N were monitored and simulated with the Detran model. A third stable microbial biomass fraction had to be introduced in the model to simulate the dynamics of glucose, because > 90 mg ¹⁴C kg^?1 soil persisted in the soil microbial biomass after 97 days. The observed priming effect was mostly due to an increased decay of soil organic matter, but an increased turnover of the microbial biomass C contributed somewhat to the phenomenon. The dynamics of NH₄⁺ and NO₃^– in the NH₄⁺‐amended soil could not be simulated unless an immobilization of NH₄⁺ into the microbial biomass occurred in the first day of the incubation without an immediate incorporation of it into microbial organic material. The dynamics of C and a priming effect could be simulated satisfactorily, but the model had to be adjusted to simulate the dynamics of N when NH₄⁺ was added to alkaline saline soils.     

陕西省几种代表性土壤NH4+吸附、解吸动力学特征研究

采用连续液流法测定了五种土壤吸附、解吸ＮＨ＾＋４的动力学性质。研究表明：（１）ＮＨ＾＋４吸附、解吸平衡时间及反应速率，平衡时的吸附、解吸量及吸附平衡常数均随土壤粘粒和ＣＥＣ不同而变化；（２）不同动力学模型及同一模型对不同土壤的拟合性不同。     

Leaching behaviour of a sandy soil amended with natural and NH4+ and K+ saturated clinoptilolite and chabazite

Using saturated or enriched zeolites as slow release fertilizers (SRFs) is considered as an environmental-friendly strategy to enhance use of macronutrients in sandy soils. In this paper, two natural zeolites, clinoptilolite (CLI) and chabazite (CHA) were used as mineral precursors to prepare NH₄⁺/K⁺ saturated clinoptilolite (NH₄⁺/K⁺-CLI) and chabazite (NH₄⁺/K⁺-CHA) as zeolitic nutrient sources (ZNSs). Comparison between the nutrient retention capabilities of these ZNSs was one of the main objectives of this study. The NH₄⁺/K⁺-CLI and NH₄⁺/K⁺-CHA were prepared by soaking the zeolites in NH₄Cl and KCl solutions, respectively. Leaching tests were performed on a sandy soil amended with chemical fertilizers (CFs), NH₄⁺/K⁺-CLI and NH₄⁺/K⁺-CHA to evaluate the leaching properties of them. The results indicated that approximately 84% and 88% of the NH₄⁺ and K⁺ of soils fertilized with CFs were lost during the experiment, respectively. While, the NH₄⁺ and K⁺ losses from soils amended with NH₄⁺/K⁺-CLI and NH₄⁺/K⁺-CHA were 29%, 23%, and 14%, 24%, respectively. Despite of drastic changes in leaching behavior of CFs, nutrient losses from ZNSs were more uniform during the experiments. No significant difference was found between the two studied zeolites on reduction of K⁺ loss. However, CHA was more effective in preventing NH₄⁺ loss during leaching.     

铵硝营养对水稻氮效率和矿质养分吸收的影响

NH_4~+和NO_3~–是对植物有效的两种主要无机氮源。水稻一般被认为是偏好NH_4~+的植物,但是在NO_3~–条件下,水稻也能良好地生长。大多数关于水稻铵硝营养的报道是在pH 6.0左右的水培条件下开展的,但是对于酸性条件下水稻铵硝营养研究很少。随着土壤酸化的加重及一些边际酸性土壤被用作水稻种植,研究酸性条件下水稻的铵硝营养具有重要意义。本文采用水培试验,在pH 5.0的条件下,通过添加和不添加pH缓冲剂MES(2-(N-吗啡啉)乙磺酸),研究了NH_4~+和NO_3~–对水稻生长、氮效率和矿质养分(N、P、K、Ca、Mg、Fe、Zn、Cu、Mn)吸收的影响。结果表明,在不添加MES的条件下,水稻地上部生长(株高、叶绿素含量、干重)在NH_4~+和NO_3~–之间没有显著差异,而添加MES后,NH_4~+处理的水稻地上部生长优于NO_3~–。不管是否添加MES,NO_3~–处理的水稻地下部生长(根长、根表面积和根物质量)优于NH_4~+。水稻含氮量和氮利用效率在不同NH_4~+和NO_3~–处理之间没有显著差异,但是NH_4~+处理的水稻氮吸收效率高于NO_3~–。与NO_3~–相比,NH_4~+增加了水稻地上部P和Fe含量,而降低了水稻地上部Ca、Mg、Zn、Cu和Mn含量,对K含量影响较小。上述结果表明,NH_4~+有利于改善水稻地上部生长,提高氮吸收效率、地上部P和Fe含量,而NO_3~–则有利于水稻发根,提高地上部Ca、Mg、Zn、Cu和Mn含量。     

Evaluation of Extractants and Quantity–Intensity Relationship for Estimation of Available Potassium in Some Calcareous Soils of Western Iran

Accurate estimation of the available potassium (K⁺) supplied by calcareous soils in arid and semi‐arid regions is becoming more important. Exchangeable K⁺, determined by ammonium acetate (NH₄OAc), might not be the best predictor of the soil K⁺ available to crops in soils containing micaceous minerals. The effectiveness of different extraction methods for the prediction of K‐supplying capacities and quantity–intensity relationships was studied in 10 calcareous soils in western Iran. Total K⁺ uptake by wheat grown in the greenhouse was used to measure plant‐available soil K⁺. The following methods extracted increasingly higher average amounts of soil K⁺: 0.025 M H₂SO₄ (45 mg K⁺ kg^?1), 1 M NaCl (92 mg K⁺ kg^?1), 0.01 M CaCl₂ (104 mg K⁺ kg^?1), 0.1 M BaCl₂ (126 mg K⁺ kg^?1), and 1 M NH₄OAc (312 mg K⁺ kg^?1). Potassium extracted by 0.01 M CaCl₂, 1 M NaCl, 0.1 M BaCl₂, and 0.025 M H₂SO₄ showed higher correlation with K⁺ uptake by the crop (P < 0.01) than did NH₄OAc (P < 0.05), which is used to extract K⁺ in the soils of the studied area. There were significant correlations among exchangeable K⁺ adsorbed on the planar surfaces of soils (labile K⁺) and K⁺ plant uptake and K⁺ extracted by all extractants. It would appear that both 0.01 M CaCl₂ and 1 M NaCl extractants and labile K⁺ may provide the most useful prediction of K⁺ uptake by plants in these calcareous soils containing micaceous minerals.     

The H+/M2+ exchange stoichiometry of calcium and zinc adsorption by ferrihydrite

The specific adsorption of Ca²⁺ and Zn²⁺ by ferrihydrite results in the net release of H⁺. The rate and H⁺/M²⁺ exchange stoichiometry of this reaction were monitored with a pH-stat. A rapid reaction of less than 6 min was followed by a slower reaction which continued at a diminishing rate for at least 2 days. Adsorption of Ca²⁺ at pH 7.8 and Zn²⁺ at pH 5.4 resulted in the net release of 0.92 and 1.70 mol H⁺/mol M²⁺ adsorbed, respectively. For Zn²⁺ adsorption, this stoichiometry was shown to be independent of pH. These estimates agree well with independent estimates based on the pH dependence of adsorption. The difference between the Ca²⁺ and Zn²⁺ stoichiometries was related to the differing acidity of the –OH₂ ligands attached to the adsorbed ions.     

Acetylene and N-serve effects upon N2O emissions from NH4+ and NO3− treated soils under aerobic and anaerobic conditions

N₂O emissions from soils treated with NH₄⁺-N under aerobic conditions in the laboratory were 3- to 4-fold higher than those from controls (no extra N added) or when NO₃^?-N was added. Although the emission of N₂O-N in these field and laboratory experiments represented only 0.1–0.8% of the applied fertilizer NH₄⁺-N and are therefore not significant from an agronomic standpoint, these studies have conclusively demonstrated that the oxidation of applied ammoniacal fertilizers (nitrification) could contribute significantly to the stratospheric N₂O pool.Like N-serve, acetylene was shown to be a potent inhibitor of nitrification as it stopped the oxidation of NH₄⁺-N to (NO₃⁺-N + NO₂^?)-N and hence reduced the evolution of N₂O from nitrification within 60 min after its addition.Although high amounts of NO₃^?-N were present, the rate of denitrification was very low from soils with moisture up to 60% saturation. The further increase in the degree of saturation resulted in several-fold increase of denitrification which eventually became the predominant mechanism of gaseous N losses under anaerobic conditions.