应用离子交换树脂膜测定土壤钾素有效性的研究

用国产离子交换树脂膜室内埋置法提取测定了我国北方２４种土壤的速效钾含量。结果表明,用阳离子交换树脂膜提取的土壤钾与用１ｍｏｌ／Ｌ中性ＮＨ４ＯＡｃ及土壤养分综合系统评价方法提取的钾（ＡＳＩ－Ｋ）分别呈显著和极显著的正相关;与盆栽试验不施钾处理玉米幼苗吸钾量呈极显著的正相关,明显高于常用的１ｍｏｌ／Ｌ中性ＮＨ４ＯＡ提取钾与锱某试验玉米幼苗吸钾量之间的相关性。说明可以用国产离子交换树脂膜较好地评价北方土     

离子交换树脂膜吸附土壤养分的动力学研究

采用从英国进口的离子交换树脂膜和室内埋置法研究了取自河北玉田县的4个土壤吸附土壤磷、钾、钙、镁和锰的动力学。结果表明，在0.5-26h的吸附时间内，随着提取时间的延长，树脂膜吸附的土壤磷、钙量和锰量显著增加，而吸附的钾量减少。     

离子交换树脂膜埋置法测定土壤中的有效养分

离子交换树脂在农业上的应用已有近50年的历史,早期的研究主要集中在用阴离子交换树脂提取土壤中的磷;然后用阳离子交换树脂研究了土壤中钾的有效性及缓效钾的释放,后来开始用离子交换树脂测定土壤中营养元素。离子交换树脂在测定土壤养分的研究方面经历了树脂颗粒、树脂袋和树脂膜三个阶段。     

不同类型的离子交换树脂对土壤速效钾测定的影响

通过室内模拟试验研究，结果表明：不同类型的离子交换树脂膜在饱和溶液中的吸附曲线基本相同，但对钾的吸附数量差异很大，国产树脂膜对钾离子的平均饱和吸附量为8303.6μg/cm^2。而进口树脂膜对钾离子的平均饱和吸附量为2209.8μg/cm^2，仅是国产膜的26.6%，在土壤中，离子交换树脂膜对钾的吸附量随时间呈对数关系，在开始2小之内，雨过天青者的吸附量差异不大，以后随时间的延长，二者的吸附量差异逐渐增大，在钾离子的测定中，进口膜通过接触交换至膜上的钾离子数量占总比例为25%，而国产膜为38.5%，土壤含水量对土壤钾的测定有很大影响。     

离子交换树脂膜吸附土壤养分的动力学研究

采用从英国进口的离子交换树脂膜和室内埋置法研究了取自河北玉田县的 4个土壤吸附土壤磷、钾、钙、镁和锰的动力学。结果表明 ,在 0 .5～ 2 4h的吸附时间内 ,随着提取时间的延长 ,树脂膜吸附的土壤磷、钙量和锰量显著增加 ,而吸附的钾量减少。     

离子交换树脂膜测定肥料养分在土壤中的变化

在25℃恒温培养条件下,采用离子交换树脂膜(IERM)连续提取法研究了不同肥料(尿素、氯化钾、磷酸二氢钙、缓释复合肥)养分(氮、磷、钾)在土壤中的变化。结果表明,几种肥料养分释放速率各异,缓释复合肥氮、磷养分释放在前期(28 d)释放较慢。用该方法提取肥料养分(N、P、K)在土壤中的释放累积量随时间的增加而增大,用Elovich、双常数、一级扩散、抛物线扩散4种动力学方程来描述二者的关系,拟合度都达到了极显著水平(r=0.863^**～0.999^**)。用该法测定肥料在土壤中释放养分的变化特性与用其测定的土壤本身养分的变化特性相似。从而提出了离子交换树脂膜法作为一种评价肥料养分在土壤中的变化特性的较理想方法的可能性。     

不同类型的离子交换树脂对土壤速效钾测定的影响

通过室内模拟试验研究,结果表明不同类型的离子交换树脂膜在饱和溶液中的吸附曲线基本相同,但对钾的吸附数量差异很大,国产树脂膜对钾离子的平均饱和吸附量为8303.6μg/cm2,而进口树脂膜对钾离子的平均饱和吸附量为2209.8μg/cm2,仅是国产膜的26.6%.在土壤中,离子交换树脂膜对钾的吸附量随时间呈对数关系,在开始2小之内,二者的吸附量差异不大,以后随时间的延长,二者的吸附量差异逐渐增大.在钾离子的测定中,进口膜通过接触交换至膜上的钾离子数量占总比例为25%,而国产膜为38.5%,土壤含水量对土壤钾的测定有很大影响.     

测定土壤有效钾的新方法—阳离子交换树脂膜法

对采自全国各地 2 0个土壤样品进行测定 .结果表明 ,阳离子交换树脂膜埋置法测定土壤有效钾的最佳埋置时间为 2 0min .树脂膜法测定的土壤钾值与中性醋酸铵法测定的土壤有效钾和植物实际吸钾量之间具有极显著的相关性 .国产树脂膜可代替进口树脂膜用于土壤有效钾测定     

国产和进口阴离子交换树脂膜埋置法测定土壤中的微量元素

对采自全国各地 2 0个土壤样品进行测定 .结果表明 ,树脂膜法测定的土壤微量元素值与DT PA法测定的土壤有效微量元素之间具有极显著的相关性 ,国产树脂膜的测定值与DTPA法测定值间的相关性稍优于进口树脂膜 .阴离子交换树脂膜法测定的土壤有效Mn与植物实际吸Mn量间的相关性好于DTPA法测定值与植物实际吸Mn量间的相关性 ,国产树脂膜法测定值与植物实际吸Mn量间的相关性稍好于进口树脂膜 ,指数相关性好于一次直线相关性 .离子交换树脂膜法可以用来测定原位土壤中的有效微量元素 ,国产树脂膜可以替代进口树脂膜 .     

应用离子交换树脂膜法评价缓释复合肥料供肥特性的研究

在25℃连续恒温培养条件下,采用离子交换树脂膜(IERM)提取,测定了不同缓释复合肥料(SRCF)在土壤中的氮、磷、钾养分的供肥特性,并与盆栽水稻的养分吸收进行比较。结果表明:56.d内2种SRCF在土壤中NO3--N和NH4+-N养分的日均供应量占普通复合肥(NCF)的3.3%～58.1%,并以NH4+-NNO3--N;2种SRCF的H2PO4-和K+的日均供应量占磷、钾施用量分别为NCF的14.9%、23.2%和92.7%、64.5%。与NCF相比,SRCF氮素和磷素养分在土壤中释放具有明显的缓释作用。Elovich和抛物线扩散方程的b值可分别用来表征SRCF的NO3--N、H2PO4-和NH4+-N、K+养分在土壤中释放后被吸收的日均供肥量。用离子交换树脂膜法提取测定的SRCF养分在土壤中的供肥特性与该法测定的土壤本身养分的供肥特性相似。SRCF氮、磷、钾养分累积释放量与盆栽水稻氮、磷、钾养分吸收量呈显著或极显著的正相关(r=0.869～*0.994**)。用离子交换树脂膜提取测定和评价缓释复合肥料在土壤中养分的供肥特性是一种比较理想的方法。     

Analysis of imazethapyr in agricultural soils by ion exchange membranes and a canola bioassay

Abstract

Because imazethapyr residues in soils may cause plant injury to certain rotational crops, sensitive, and reliable methods for imazethapyr monitoring in soils are needed. In this study, imazethapyr analysis was investigated using two newly developed procedures: an anion exchange membrane extraction followed by an HPLC‐UV detection and a canola bioassay. Nine soils in which no previous application of imazethapyr had been made were collected from farm fields in Saskatchewan, Canada. Soils were spiked to yield imazethapyr concentrations in the range of 0–80 μg kg^‐1 dry soil and were subjected to analysis by the above procedures. In the anion exchange membrane extraction, spiked soils were shaken with the membrane strips; imazethapyr was then eluted from the membranes with a potassium chloride (KC1) solution, partitioned into dichloromethane and injected into the HPLC. This method allowed for the extraction of the ionized portion of imazethapyr from soils. In a laboratory bioassay, pre‐germinated canola seeds were planted in spiked soils and after five days of growth root and shoot growth inhibition was determined. The results of both methods were dependent on soil type. Generally, soils from depressions in the landscape yielded low imazethapyr recovery by anion exchange membrane extraction; these soils also showed low degree of imazethapyr phytotoxicity to canola growth. After imazethapyr field spraying, soils were sampled from the field at different time intervals for up to one year and analyzed in the laboratory by the above methods; also, after one year, a field bioassay was performed. Using the membrane extraction method, imazethapyr was detected only in field samples collected one week after spraying. The membrane extraction method, although very simple and cost‐efficient lacks sensitivity needed for the imazethapyr monitoring at low concentrations in agricultural soils. The 5‐day canola bioassay (root growth inhibition method) was more sensitive than the membrane extraction and showed imazethapyr presence in all field samples. However, because crop growth inhibition was more severe in the field than in the laboratory, a field bioassay may be the most reliable means to assess injury potential for certain sensitive rotational crops under field conditions.     

Purification of humic acid by the use of ion exchange resin

Abstract

The humic acid fraction, extracted from soil by alkali or neutral salt solution and acid-recipitated, is generally contaminated with a considerable amount of inorganic matter. The presence of the inorganic matter is often undesirable for studies on humic acid. The inorganic matter is generally taken off by ultrafiltration or electrodialysis. But these methods take time and are unsuitable for the bulk preparation of humic acid.     

A comparison of three methods of determining the cation exchange capacity of calcareous soils

Three widely used methods for cation exchange capacity determination, viz. sodium acetate, Bascomb's and ⁴⁵Ca isotopic dilution methods have been compared. Sodium acetate and Bascomb's methods gave similar values for most of the samples. Though some correction for the organic matter and calcium carbonate content are of concern for the ⁴⁵Ca method, the results do not preclude use of the latter for the cation exchange capacity determination.In the ⁴⁵Ca method organic matter contributed mostly to the cation exchange capacity, whereas for the other two methods the relative contribution of clay was found to be higher. The lowest contribution of calcium carbonate to the cation exchange capacity was observed in Bascomb's method. Simple and multiple regression relationships between cation exchange capacity and organic matter, clay and calcium carbonate are discussed.     

测定土壤有机质氧化条件的研究

丘林法测定土壤有机质因加热介质和氧化条件的不同,其氧化程度也不一样.应用GBW07401～07406国家标准物质筛选出土壤有机质测定的加热介质和氧化条件--甘油浴8min.快速方便,结果准确可靠.     

Principles underlying the practice of determining lime requirements of acid soils by use of buffer methods

Abstract

A buffer is generally a mixture of a weak acid and a salt of the same weak acid. Hence it can neutralize both acids and bases, and thus resists marked changes in pH of a system. Yet systematic change in pH of a buffer caused by addition of an acidic substance can be used to indicate the total acidity represented by the change in buffer pH. Since acid soil is itself a buffer, when it is added to a buffer mixture for the purpose of measuring its acidity or lime requirement (LR), the resulting double‐buffer suspension (soil‐buffer) is a relatively complex system. Much of the complication in interpreting the changes in buffer pH brought about by mixing soil and buffer stems from the facts: i) that much of the acidity is pH‐dependent, and ii) that quick‐test methodology involves reaction of only a fraction of the total soil acidity with the buffer. Marked change in relative amounts of H ions dissociating from the soil‐SMP‐buffer system at soil‐buffer pH 6.9 and above accounts for relatively wide variations between buffer‐indicated and CaCO₃ incubation‐measured LR of low LR soils. Similarly, decreased reactivity of H⁺ in high organic matter soils and increased reactivity of H in acid‐leached soils cause errors in buffer‐indicated LR. Awareness of these principles helps avoid pitfalls of existing buffer methods, and has led to incorporation of the double‐buffer feature for improving the SMP method.     

Evaluation of universal extractants for determining plant available potassium in intensively cultivated soils

Abstract

Eighteen soils from northwestern Switzerland were used to study the value of seven universal extractants (CaCl₂; DB‐DTPA; Mehlich 1, 2, and 3; Morgan‐Wolf; and NH₄OAc‐EDTA) for predicting plant available potassium (K) as compared to a bioassay (a modified Neubauer test with winter rye). These extractants were evaluated on the basis of K uptake by the bioassay test and the soil K status. In order to create the sufficiency level of exchangeable K for plant growth, soils were treated with 0, 20, 40, 80, and 160 mg K/kg of soil. The range of K uptake by the bioassay tests was between 89.2 and 403.0 mg/kg of soil for the control pots, and 136.6 to 495.8 for the K treatments with optimal conditions for plant growth. The average amounts of K extracted by the seven universal extractants, in ascending order, were: CaCl₂ < Morgan‐Wolf < Mehlich 1 < Mehlich 2 < NH₄OAc‐EDTA < Mehlich 3 < DB‐DTPA. The highest simple correlation with K uptake versus the bioassay test was obtained with the DB‐DTPA (r = 0.89) extractant and the lowest with the Mehlich 1 (r = 0.53) extractant. The DP‐DTPA, NH₄OAc‐EDTA and Mehlich 3‐K procedures showed an advantage over K procedures based on water soluble and exchangeable K pools in the investigated soils in order to predict the amount of plant‐available K. A simple regression and the Cate‐Nelson graphic method offer the possibility of assessing the soil‐K status using K values obtained by these universal extractants and to calibrate them against K forms as follows: exchangeable, water soluble, and non‐exchangeable.