Simultaneous determination of copper and iron in plant material by an automated method

Abstract

Existing colorimetric manual methods for copper and iron have been adapted for simultaneous analysis by an automated method. Fifty samples per hour can be assayed. Calculation of results as parts per million in dry matter has been eliminated by a standardized weighing technique of the plant material.     

An automated colorimetric method for the determination of urease activity in soil and plant material

Abstract

An automated colorimetric method Cor determining urease activity in soils and plant material is described. The method, using ammonium determination by the nitroprusside‐catalysed indophenol reaction, is Caster and more precise than a colorimetric measurement of urea.     

Simultaneous determination of total C,total N,and 15N on soil and plant material

Abstract

Availability of labor and laboratory instrumentation has frequently limited use of isotopes in N management research. Recent innovations in laboratory instrumentation have made it possible to simultaneously determine total C, total N, and ¹⁵N concentrations in plant, soil, and water samples. An automatic C and N analyzer was interfaced with a continuous‐flow mass spectrometer for purposes of routine analytical determinations. Compared to manual procedures, the automated procedure was rapid, accurate, and gave reproducable results both over time and between adjacent samples. Ball‐mill preparation of samples greatly increased precision of determinations and is recommended to improve sample homogeneity.     

紫色土施用磷酸盐肥料对玉米铜毒害的缓解

A pot experiment was conducted to evaluate the effects of phosphorus fertilizer in inhibiting the copper toxicity to maize(Zea mays L.) in neutral purple soil. Results indicated that the growth of the shoot and roots of maize plant was obviously reduced by copper and the height and biomass were significantly negatively correlated to the application levels of copper (r = -0.899^**~-0.994^**) at no P and low P (100 mg kg^-1). However, the maize biomass was relatively increased and the high Cu (100 and 200 mg kg^-1) induced toxicity of maize was greatly alleviated in all treatments with medium P (300 mg kg^-1 ) and high P (500 mg kg^-1). To maintain the normal growth of maize plant (≥3.68 g pot^-1), the critical application rates of phosphorus fertilizer should be 160, 210, 300 and 500 mg P kg^-1 at 10, 50, 100 and 200 mg Cu kg^-1 levels of the soil, respectively. The increases in polyphenol oxidase and catalase activities in maize leaf and dehydrogenase activity in roots by phosphorus fertilizer were in the order of medium P>high P>low P>no P. Activities of polyphenol oxidase and catalase were significantly positively correlated to the application levels of copper (r =0.892^**~0.924^**), whereas that of dehydrogenase was just reverse (r = -0.966^**) at no P. Medium and high P repressed the influence of copper on activities of three enzymes. Phosphorus fertilizer reduced the copper concentrations of maize roots and leaf and the change ranges of the P/Cu ratio of maize roots and the P/Cu, N/Cu and K/Cu ratios of maize leaf. The three ratios of maize leaf were 256^**71.5, 2643^**839 and 1133^**440 at normal growth of maize plant, respectively. Soil available Cu could be markedly cut down by application of phosphorus fertilizer, especiallly at high phosphorus level.     

Zinc and copper toxicity in peanut,soybean, rice,and corn in soil mixtures

Abstract

Applications of zinc (Zn) and copper (Cu) at excessive rates may result in phytotoxicity. Experiments were conducted with mixtures of soils that were similar except for their Zn and Cu levels. The critical toxicity levels (CTL) in the soils and plants for these elements were determined. Peanut (Arachis hypogaea L.), soybean [Glycine max (L.) Merr.], corn (Zea mays L.), and rice (Oryza sativa L.) were the crops grown. One soil mixture had Mehlich 3‐extractable Zn concentrations up to 300 mg dm^‐3 with no corresponding increase in soil Cu; two soil mixtures had soil Zn concentrations up to 400 and 800 mg dm^‐3 with a corresponding increase in soil Cu up to 20 and 25 mg dm^‐3, respectively; and four soil mixtures had no increase in soil Zn, but had Mehlich 1‐extractable Cu concentrations from 6 to 286 mg kg^‐1. Under a given set of greenhouse conditions, the estimated Mehlich 3‐extractable Zn CTL was 36 mg dm^‐3 for peanut, 70 mg dm^‐3 for soybean, between 160 and 320 mg dm^‐3 for rice, and >300 mg dm^‐3 for corn. No soil Cu CTL was apparent for peanut or soybean, but for corn it was 17 mg dm^‐3 and for rice 13 mg dm^‐3. With different greenhouse procedures and the Mehlich 1 extractant, the soil CTL for rice was only 4.4 mg kg^‐1. Therefore, peanut and soybean were more sensitive to Zn toxicity, whereas corn and rice were more sensitive to Cu toxicity. Plant Zn CTL for peanut was 230 mg kg^‐1, while that for soybean was 140 mg kg^‐1. Copper appeared to be toxic to corn and rice at plant concentrations exceeding 20 mg kg^‐1.     

Phosphorus leaching in a calcareous soil treated with plant residues and inorganic fertilizer

Column experiments were conducted over 45 d to determine the degree of P mobility. The sandy loam soil was spiked with 200 mg P kg^–1 and 5% organic residues. The treatments included: control without any water‐soluble P and plant residues, potato, wheat, water‐soluble P fertilizer, wheat + water‐soluble P, and potato + water‐soluble P. Each column was leached with distilled water, and leachates were collected and analyzed for P, K⁺, Ca²⁺, Mg²⁺, along with pH and EC. Sequential extraction was performed on soil samples at the end of leaching column experiments. The relatively high initial concentration of P in the leachates decreased to more stable values after 15 d which can be attributed to the colloid‐bound P. The P concentrations in the leachates fluctuated between 8 and 220 mg L^–1 in the water‐soluble–P fertilizer treatment, between 0.80 and 230 mg L^–1 in the potato + water‐soluble‐P treatment, and between 0.90 and 214 mg L^–1 in the wheat + water‐soluble P treatment. Leaching loss of P mainly occurred in the 15 d of leaching, accounting for 94%, 88%, and 65% of total P leached in wheat + water‐soluble‐P, potato + water‐soluble‐P, and water‐soluble‐P treatments, respectively. Maximum amount of P leached was found from an exponential kind model and was in the range 0.45 mg kg^–1 to 125.4 mg kg^–1 in control and potato + water‐soluble‐P treatments, respectively. Sequential extraction results showed that in control and amended soils the major proportion of P was associated with Ca. The leachate samples in all treatments were saturated with respect to hydroxyapatite, β‐tricalcium phosphate, and octacalcium phosphate up to 20 d of leaching, whereas they were undersaturated with respect to Mg‐P minerals through the entire leaching experiment.     

双波长分光光度法测定土壤硝态氮

研究了双波长分光光度法测定土壤中的硝态氮,结果与酚二磺酸法相符,样品标准加入回收率为90%~109%,RSD为2.22%~3.45%。结果表明:该方法具有选择性好、灵敏度高、操作简便、测定范围宽、能有效消除亚硝酸盐、氯离子、有机物的干扰等优点。     

双波长分光光度法测定土壤硝态氮

研究了双波长分光光度法测定土壤中的硝态氮，结果与酚二磺酸法相符，样品标准加入回收率为90％-109％，PSD）为2．22％-3．45％。结果表明；该方法具有选择性好、灵敏度高、操作简便、测定范围宽、能有效消除亚硝酸盐、氯离子、有机物的干扰等优点。     

Quantitative determination of nitrogen content in plant tissue by a colorimetric method

Abstract

This study was to evaluate the applicability of a colorimetric method in measuring the nitrogen (N) concentration in samples of vegetable origin. In order to do this, the same samples were analyzed with a colorimetric, and macro‐ and microKjeldahl methods. The colorimetric method has been used successfully in the determination of N in nutritional studies with rats and humans. The present procedure has the advantage of eliminating the distillation and titration steps of the Kjeldahl method and it is practical for nutritional studies, since many samples can be run in a single day. The N concentration was measured in leaves of two tropical grasses: Paspalum fasciculatum Willd. ex Flugge and Hyparrhenia rufa (Nees) Stapf, and a Standard Reference Material (SRM 1547 Peach Leaves). In all cases, there were no significant difference (P>0.05) in N concentration in these plant materials using the colorimetric, and micro‐ and macroKjeldahl methods. There was a good agreement between the N concentration of Peach leaves determined by the colorimetric method (2.94%) and the certified N concentration (2.94%). Hyparrhenia rufa, the African grass, and P. fasciculatum, the native species, showed very low N concentration in their leaves, respectively. These results indicate that the colorimetric method, with some light adjustments, is capable of determining the N concentration in plant samples of diverse origin and in very low N levels. The low N concentrations of the grass species suggest the strong limitation imposed by the low soil fertility for the growth and establishment of forage species in tropical savannas.     

自动电位滴定法测定肥料和土壤中氯离子含量

介绍了自动电位滴定法测定肥料和土壤中氯离子含量的方法，采用了简单的前处理步骤，与佛尔哈德法及莫尔法相比，具有快速、准确、精密度高的优点，且不受溶液颜色和浊度的干扰。     

Microbiological and chemical determination of copper and zinc in soil

Many chemical and microbiological methods to estimate the amounts of available nutrients in soil were proposed, but as a rapid laboratory method, microbiological test would appear to have advantages over chemical methods. It could be done more simply and inexpensively in various points.     

Effect of fertilizer,herbicide and grazing management of pastures on plant and soil communities

Increases in fertilizer inputs and livestock numbers affect plant species composition and richness; this in turn can affect the biodiversity of soil fauna and nutrient cycling in pastures. We selected two adjacent farmlets to study these effects. Since 1980, one farmlet (LF) had not received superphosphate fertilizer (SSP) and has a low stock density of sheep, and the other (HF) had received 37.5 g SSP m⁻² y⁻¹ and has a high stock density. In 2004, at both farmlets, we commenced treatments for 4 years, adding urea to raise N status, and non-residual selective herbicide to remove broadleaf species. Long-term SSP addition and increased sheep numbers, and added urea increased herbage production but reduced plant diversity. The effect of treatments on most of the soil biochemical and biological properties varied between years. This may have partly arisen from an infestation with Wiseana caterpillars in the first winter, causing resources to be low and total soil carbon (C) to be reduced by 4–8%; total C did, however, recover in later years. The urea and herbicide treatments caused greater changes above-ground than below-ground, but they did reduce soil microbial C and N and nematode diversity; urea at LF increased mineralizable N to the levels found at HF. On an area basis, HF generally had higher total C and N, earthworm and nematode numbers (including bacterial feeders, predators and omnivores), and nematode diversity, and greater values for the nematode channel ratio, than did LF. In contrast, the ratios of microbial C/total C and microbial N/total N, total mite numbers (including Oribatida, but not other mite groups), and fungal-feeding nematode numbers were higher at LF than at HF. Canonical correlation analysis suggested the plant and soil nematode communities responded in tandem and in predictable ways to the same environmental factors. Increased quantity and quality of inputs disadvantaged the fungal-based energy channel, with a measurable decline in the quantity of fungal phospholipid fatty acids (PLFAs). While the quantity of bacterial PLFAs appeared to be unaffected by greater plant-derived inputs, the greater numbers of bacterial-feeding nematodes at the HF farmlet suggests the activity and flow of energy and nutrients through the bacterial community would be more important in the HF than the LF farmlet. Overall our results suggest the shift from fungal to bacterial pathways may lead to soil microbial/microfaunal interactions that retain less reactive N within soil biomass, with a consequent greater risk of N loss.     

Modification and application of a soil ATP determination method

Accurate estimation of microbial adenosine 5′-triphosphate (ATP) is a pre-requisite to quantify the impact of varying environments on microbial activity of soil. We investigated the effectiveness of a high efficiency soil ATP determination method (PA) [Webster, J.J., Hampton, G.J., Leach, F.R., 1984. ATP in soil: a new extractant and extraction procedure. Soil Biology & Biochemistry 4, 335-342] in 10 Ontario (Canada) soils collected along a 100 m transect and spanning a textural class gradient ranging from a sandy loam to clay loam with increasing organic matter. Modifications of the method involved using an extract of autoclaved soil to make the standard curve, as it was found that the light emitted by ATP luciferin-luciferase bioluminescence reaction in the pure extractant was different from that in the extracts. Replacing Tricine with Tris buffer in the assay significantly improved the light emission. On an average, the internal standard calibration method (ISM) measured a smaller amount of extracted ATP (1199 ng ATP g⁻¹ soil) and a lower recovery of ATP spike (82.4±7.2%) than did the standard curve method (SCM) (1246 ng ATP g⁻¹ soil and 91.2±4.5%, respectively) (P<0.05 for both comparisons). However, the average total estimated ATP was higher with ISM (1474±102 ng ATP g⁻¹ soil) than with SCM (1373±88 ng ATP g⁻¹ soil) (P<0.07). While the recovery rates determined using SCM were consistent among the soils tested, the rates measured using ISM was negatively correlated with soil clay and organic matter content, implying that the latter assay was affected by the soil properties. Our results confirmed that the recovery rates obtained by the PA method were the highest among those reported, when only SCM was used.     

Ammonium determination in soil extracts by the salicylate method

Abstract

An ammonium determination, based on formation of a substituted indophenol with sodiumsalicylate as phenolic reagent, has been reexamined. An increase of 70% in absorbancy compared with existing salicylate methods in soil science, and an increase in reproducibility compared with pre‐existing equivalent methods in other disciplines were obtained. The method can be applied satisfactorily for ammonium in 2M KCl soil extracts and soil and plant digests. The use of salicylate in place of phenol is advised for safety reasons.     

Simple spectrophotometric method for determination of phosphine residues in wheat

A method has been developed for determination of phosphine residues in wheat, based on the reaction of phosphine with silver nitrate in aqueous solution to form an egg-yellow chromophore with an absorption maximum at 400 nm. At this wavelength, there is a linear relationship between absorbance and concentration of phosphine in the range 10-100 ng/mL. Phosphine-fumigated wheat is soaked in a known volume of AgNO3 solution, and the absorbance of the filtrate is read against a blank at 400 nm. The method is sensitive, with lower detection and estimation limits of 0.008 and 0.01 micrograms PH3, respectively. Recovery of added phosphine from a closed system was 85-100%. Accuracy for this method has been compared with that for the gas chromatographic method.     

The determination of phosphorus in Kjeldahl digests of plant material by automatic analysis

Abstract

A method is proposed for the determination of phosphorus in plant material using a modified Kjeldahl digestion and a Technicon Autoanalyzer. The procedure depends upon the formation of phosphomolybdate and its reduction to molybdenum blue by ferrous ammonium sulphate. The method enables the simultaneous determination of phosphorus and nitrogen on the same plant digest.     

Automatic determination of boron in water samples and soil extracts

Abstract

An automatic fluorimetric method for the determination of boron in water samples and soil extracts is described. Automatic wet digestion of the samples by UV irradiation, eliminates interference by organic matter. An ion exchange resin incorporated in the system removed interference caused by metal cations. The analysis is performed at pH 7. The linear working range is 0 ‐ 3 mg 1^?1 of boron with a detection limit of 0.01 mg 1^?1 of boron. The capacity of the method is a minimum of 20 samples per hour and the precision is s = 0.004 mg 1^?1 of boron in the range 0 ‐ 3 mg 1^?1 of boron.     

Tillage,fertilizer type,and plant residue input impacts on soil carbon sequestration rates on a Japanese Andosol

ABSTRACT

To identify efficient field management practices for enhanced soil carbon sequestration suited to crop rotation-based Andosol fields in northern Japan, the impacts of a combination of tillage, fertilizer type, and plant residue input on soil carbon sequestration rates were studied in a 4-year field experiment (April 2007 to March 2011). The rates of changes in soil organic carbon over the entire study period were determined by soil carbon stock change and by net ecosystem carbon budget. Across eight field management treatments and two replicates for each treatment, the rates of changes in soil organic carbon determined by net ecosystem carbon budget were positively correlated with the rates determined by soil carbon stock change (r = 0.766, n = 16). The arithmetic means of the rates determined by net ecosystem carbon budget (1.24 Mg C ha^?1 year^?1) were greater than those determined by soil carbon stock change (?0.18 Mg C ha^?1 year^?1) because decomposing crop residues and composted cattle manure in soil were included in the calculation of the net ecosystem carbon budget but were excluded in the calculation of soil carbon stock change (decomposing crop residues and composted cattle manure in soil samples were removed by sieving in measuring the soil carbon stock change). Both methods led to the same conclusion that soil carbon sequestration was significantly enhanced by composted cattle manure application and increased input of plant carbon from crop residues and green manure but was not enhanced by reduced tillage. The p values for net ecosystem carbon budget were smaller than those for soil carbon stock change in analysis of variance; therefore, the net ecosystem carbon budget was more sensitive to field management practice than the soil carbon stock change.     

Simple and rapid spectrophotometric method for determination of adrenaline and isoprenaline

A simple, rapid, and specific method for determination of adrenaline bitartrate and isoprenaline sulfate was developed. The method is based on the oxidation reaction in aqueous solution of either adrenaline bitartrate or isoprenaline sulfate in the presence of silver oxide to give a red aminochrome measurable at 490 nm. The color is stable for 2 h. Beer's law is valid within a concentration range of 5-80 micrograms/mL for each drug. All variables were studied to optimize the reaction conditions. The method is specific for catecholamine drugs having a secondary amine in the side chain. Other catecholamines such as orciprenaline and noradrenaline do not interfere, and no interference was observed in the presence of common pharmaceutical adjuvants. Interference due to sodium metabisulfite and sodium chloride was circumvented. The validity of the method was tested by analyzing adrenaline injections and isoprenaline tablets. Good recoveries were obtained for these preparations. The results were comparable to those obtained by official procedures. The proposed method is also recommended as a stability indicating assay for oxidative degradation of both drugs.     

Boron determination in plant tissue by the azomethine H method

Abstract

A colorimetric method using the azomethine H reagent is described for determining boron in an acid extract of plant tissue ash. The method consistently gave the certified value of 33±3 ppm B for NBS orchard leaf reference material No. 1571 with 3.2% coefficient of variation. Samples were dry ashed and the ash extracted in 10 ml 0.36 N H₂SO₄ for 1 hr. at room temperature. Several acidic extractants and extracting conditions were compared which gave the certified value, but involved heating and readjusting the final volume.