No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Comparison of Water, DTPA, and Nitric Acid as Extractants to Assess the Availability of Copper in Peat Substrates
Communications In Soil Science and Plant Analysis
Abstract
An experiment was conducted to assess the suitability of three extractants, water (H2O), 0.005M DTPA, and 0.4M nitric acid (HNO3) for determining plant available copper (Cu) in peat substrates. Cucumber was used as a test crop. Four levels of Cu were compared in two peat substrates, each at two pH levels. There was good correlation between Cu extractable in H2O, DTPA, and HN03 and the Cu content of cucumber leaves, the correlations being 0.88, 0.87, and 0.89, respectively. These correlation coefficients did not differ significantly. It was concluded that all three extractants are suitable for estimating Cu availability in peat substrates.
... Zhu e Alva (1993), trabalhando com os extratores Mehlich 1, Mehlich 3 (CH 3 COOH 0,2 mol.L -1 + NH 4 NO 3 0,25 mol.L -1 + NH 4 F 0,015 mol.L -1 + HNO 3 0,013 mol.L -1 + EDTA 0,001 mol.L -1 ) e NH 4 HCO 3 -DTPA, obtiveram menores respostas para os teores de cobre com o extrator Mehlich 1. Kreij et al. (1993), trabalhando com os extratores DTPA 0,005 mol.L -1 , HNO 3 0,4 mol.L -1 e H 2 O para avaliar a disponibilidade de cobre em substratos de turfa, obtiveram os melhores resultados com DTPA 0,005 mol.L -1 e HNO 3 0,4 mol.L -1 . Gatti et al. (1991), num experimento de campo usando 21 solos da região nordeste da Itália, avaliaram a disponibilidade do cobre para plantas de trigo, através dos extratores HCl 6 mol.L -1 , EDTA + NH 4 OAc a pH 4,65 e DTPA-TEA a pH 7,3. ...
Foram avaliados os comportamentos de extratores químicos em solos que receberam adubação de cobre, mediante dois ensaios com soja e milho como plantas testes em casa de vegetação. O delineamento experimental foi inteiramente casualizado com três repetições. Os tratamentos consistiram de três doses de Cu (0,0, 2,5 e 5,0 mg.dm-3), aplicadas na forma de solução de CuSO4.5H2O. As soluções extratoras utilizadas foram Mehlich 1 (HCl 0,05M + H2SO4 0,025M), EDTA 0,005M e DTPA 0,005M-TEA a pH 7,3, sendo os teores de cobre nos solos e nas plantas determinados por espectrometria de absorção atômica. A avaliação dos extratores foi realizada com base em regressão linear entre os teores de cobre na matéria seca das plantas e nos solos. Em ambas as culturas, o DTPA 0,005M-TEA a pH 7,3 apresentou coeficientes de correlação superiores aos demais extratores, revelando-se o melhor extrator para avaliar a fitodisponibilidade de cobre nos solos estudados.
Estudos de correlacao foram usados para avaliar a metodologias de extracao para micronutrientes em solos do Parana, visando a padronizacao dos metodos. Foram avaliados extratores acidos (Mehlich 1), na proporcao solo/extrator de 1:5 e 1:10, um extrator acido complexantes (Mehlich 3), na proporcao de 1:10, e um complexante (DTPA), na proporcao 1:2. O Mehlich 1 e Mehlich 3 foram extraidos: a) filtragem imediata apos a agitacao e b) filtragem apos decantacao de 16h. As correlacoes foram estabelecidas entre os teores no solo e em plantas de milho. Os maiores teores de Zn e Cu ocorreram com o uso do Mehlich 1 (1:10), com filtragem apos decantacao, e Mehlich 3 (1:10), com filtragem imediata e filtragem apos decantacao. Nos estudos de correlacao entre os extratores, a metodologia-padrao dos laboratorios do Parana, a qual usa o Mehlich 1, com filtragem apos decantacao, obteve boa correlacao, na determinacao do Zn, com o Mehlich 1 (1:10) e (1:5), com filtragem imediata ou apos decantacao de 16h; na determinacao do Mn e Fe, a metodologia-padrao apresentou melhor correlacao com o DTPA e com o Mehlich 3, com filtragem imediata ou apos decantacao. Para a determinacao do Cu houve equivalencia entre todas as metodologias de extracao.
An experiment was conducted to assess the suitability of three extractants, water (press‐extract and 1:1.5 volume‐extract), 0.5 M ammonium acetate (NH4OAc) and 0.005 M DTPA for determining plant available manganese (Mn) in peat substrates. Chrysanthemum morifolium was used as a test crop. Substrates were selected for differences in Mn‐content: moss peat with 0, 15, and 30% Mn‐rich clay. The three substrates with each four levels of Mn‐addition were compared. Manganese in the water‐extracts correlated well with the Mn in the plant. Poor correlations of Mn‐NH4OAc and Mn‐DTPA versus Mn in the plant were found, caused by the fact that the clay increased the Mn‐DTPA and Mn‐NH4OAc, but not Mn in the plant. The clay contained Mn which was not available. Only the water‐extracts could be used to assess the availability of Mn. The correlation coefficients of Mn‐DTPA versus Mn‐NH4OAc, of Mn‐DTPA versus Mn‐press‐extract, of Mn‐1:1.5 volume‐extract versus Mn‐NH4OAc, and of Mn‐1:1.5 volume‐extract versus Mn‐DTPA were low. Only Mn‐1:1.5 volume‐extract versus Mn‐press‐extract and Mn‐NH4OAc versus Mn‐press‐extract gave high correlation coefficients.
Two experiments were conducted to compare absorption of copper (Cu) from cupric chloride (CuCl2) and various types of chelated Cu in a low concentration range by cucumbers. In the first experiment, two varieties of cucumber were grown on rockwool for 40 days in a glasshouse with standard nutrient solution which contained six different concentrations of CuCl2 (0, 0.05, 0.10, 0.20, 0.40, and 0.80 μmol/L). Copper deficiency symptoms were examined during the growing period, and the total nitrogen (N), iron (Fe), manganese (Mn), zinc (Zn), and copper contents of young fully grown leaves were measured. There were no differences among treatments in the leaf contents of N and Mn. Copper contents increased and Zn decreased with increasing Cu levels. The content of Cu at the three low Cu treatments (including no Cu addition) were in the deficient range (48–65 μmol/kg dry matter). The zero Cu level had paler green leaves than other treatments. No differences were apparent between varieties. The second experiment was carried out under exactly the same conditions as the first, but on the basis of the results of the first experiment, Cu treatments were 0, Cu‐EDDHA at 0.4, Cu‐DTPA at 0.4, Cu‐EDTA at 0.4, Cu‐NTA at 0.4, CuCl2 at 0.4 μmo/L as Cu. After the experiment, the total N, Fe, Mn, Zn, and Cu contents of young, fully grown leaves were measured. There were no differences between treatments in the leaf contents of Cu except zero Cu level. They were in the range of 101–119 μmol/kg dry matter. At no Cu addition treatment, the Cu content was only 31 μmol/kg dry matter which is considered to be the deficiency level. For the other examined elements, there were no differences among the treatments and varieties. From these data it was concluded that the availability of these chelated Cu types were the same as CuCl2 under the conditions of the experiments conducted.
Experiments under greenhouse conditions were carried out at the Instituto Agronômico de Campinas in order to determine the efficiency of some multinutrient extradants on the determination of available copper in soils from the State of São Paulo, Brazil. These experiments employed 31 soils using wheat and beans as test plants. All soil samples were limed to increase the soil pH to 6.0 and manured with copper‐free fertilizer. Copper was extracted from the soils before liming and before each planting using the Mehlich‐1, Mehlich‐3, or the TEA‐DTPA as extracting reagents followed by its determination using the inductively coupled plasma emission spectrometry (ICP‐AES) technique. The wheat and beans plants were also analysed for their copper content. The results showed that the extraction of the available copper decreased in the order: Mehlich‐3, TEA‐DTPA and Mehlich‐1. The Mehlich‐3 (R = 0.80**) and the TEA‐DTPA (R = 0.74**) methods explained well the variation in the copper concentration found in the aerial part of the wheat plants, while the Mehlich‐1 (R = 0.45**) results were more appropriate to explain the copper concentration found in the aerial part of the beans plants. Both multinutrient extradants, Mehlich‐3 and TEA‐DTPA, proved to be the best procedures in evaluating copper availability in the Brazilian soils selected.
Agrostis capillaris ’Parys’, Beta vulgaris cicla ’Fordhook Giant’ (Swiss chard), Brassica oleracea ’Lion Heart’ (cabbage), Cineraria ’Miranda White’, Festiica rubra litoralis ‘Merlin’, Matthiola incana ‘Austral Apricot’ (stock), Phaseolus vulgaris ’Hawksbury Wonder’ (bean), and Polycarpaea spirosrylis (Copper Weed) were grown in pine bark‐based soilless media of pH 4.5, 5.5, and 6.5 amended with copper or zinc sulfate or composts containing high concentrations of either copper (Cu) or zinc (Zn). Growth responses ranged from none, through iron (Fe) deficiency, to symptoms of severe Cu or Zn toxicity. Correlations between growth and shoot Cu or Zn concentration on the one hand and total metal content of the medium and several measures of extractable metal content on the other were obtained. Medium pH had to be included in regressions to obtain high correlation coefficients. Total metal content and DTPA‐ and NH4OAc‐extractable metals were about equally well correlated with growth response in these experiments, but when the results were combined with those from an experiment in which sewage sludge was the source of Cu and Zn, DTPA‐and NH4OAc‐extractable metals gave better correlations than did total content.
Nine partial decomposition procedures and a total digestion treatment were applied to road-deposited sediments. The objective was to define a parsimonious, time-efficient decomposition procedure that (1) has limited impact on the alumnio-silicate matrix and/or refractory-associated fractions, (2) has metal recoveries independent of CaCO3 content, and (3) produces high anthropogenic signals for known contaminants (e.g., Cu, Pb and Zn). The 9 digestions varied from weak single reagents (0.11 M acetic acid) to strong multi-step procedures (BCR 3-step plus aqua regia). Eight metals were examined: Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn. Cold (room temperature) 0.5 M HCl shaken over a 1-h period with a solid-to-solution ratio of 1 g:20 ml, was judged superior based on the defined criteria. This simple, rapid treatment had limited impact on the residual matrix (mean and 95% confidence interval for Al recovery was 6±1%); recoveries of all elements examined were independent of CaCO3 content; the treatment produced high mean extraction efficiencies for Cu (58±9%), Pb (84±5%), and Zn (73±7%), and produced high anthropogenic signals. Thus, dilute HCl can be widely recommended as an optimal partial decomposition procedure for assessing non-residual fractions of complex solid media.
In 1974 the 1:1½ volume extract was published (Sonneveld et al., 1974) as a water extraction method for the determination of available nutrient elements and of the salinity status of peaty substrates. The analytical data of this extract were related to the data of the “substrate” solution extracted from the substrates with a moisture condition of -3.2 kPa. The method has been widely used and offers a suitable basis for fertilization of peaty substrates. In the years after publication, the composition and application of substrates has undergone much change and the irrigation methods have also been thoroughly adjusted. The latter was responsible for increased water contents in the substrate during crop growth. Therefore, another study was carried out in which the analytical data of the 1:1½ volume extract was compared with the analytical data of the “substrate” solution, where the “substrate” solution was defined at the moisture condition of -1.0 kPa. There was a good agreement between the results of both studies. However, the regression coefficients for the relationships between the data of the extracts differ, as expected, because of the higher moisture contents on which the substrate solution was defined. In addition to the data of major elements published, in the second study, micro nutrients were determined in the extracts, but not published. Therefore in this paper the relationships between the concentrations of micro nutrient as determined in the 1:1½ extract and in the “substrate” solution are given. The relationships presented support the interpretation of analytical data of micro nutrients by means of water extraction.
Speaking about nutrient solutions in soilless cultivation, different solutions can be discerned. Originally, in soilless culture only one nutrient solution was taken into account, being the solution in the containers in which the plants were grown. Such solutions were intensively moved by air bubbling and thus, the composition of the solution in the whole root environment was equal. The root environment was restricted to the container in which the plants were grown and thus, the whole root system of the plant was surrounded by the same nutrient solution. However, this is not the case for hydroponics and substrate systems under practical growing conditions, where great differences occur in time and place within the root environment. The main reason for these differences of salt concentrations between spots within the root environment are the inequality of water supply and water uptake by the crop as discussed in Section 6.3, at the one hand and the lack of movement of the solution within the root environment to equalize them on the other. In Chapter 8 some examples were shown of the inequality of the distribution of nutrients and salts within the root environment of substrate grown plants and the consequences of it on plant development.
Growth media used for growing containerized plants in greenhouses have changed greatly since the initiation of the Spurway test procedure (8). Well-aggregated field soils gradually gave way to mixtures of soil and manufactured coarse amendments and eventually to soilless growth media. Along with these changes in growth media composition came changes in physical and chemical properties—some desirable, some not so desirable. Field soils generally have a high-nutrient capacity value and a low-intensity factor. The level of the capacity factor has decreased as the change in growth media composition has taken place. Geraldson (1-3) developed an “intensity and balance” analysis system for the unique, sandy soils of Florida; soils that provide little buffering capacity. He found the concentration (intensity) and balance of nutrients in the soil solution to be important when the capacity factor was small. Similarly, the concentration and balance of nutrients in the solution phase of greenhouse growth media today have become important to plant growth and quality.
Concentrations of copper (Cu) in saturation extracts containing diethylenetriamine-N,N,N',N'',N''-pentaacetic acid (DTPA), and in 2 mM DTPA (1:1.5 by volume) extracts, increased linearly with additions of Cu (as CuSo4·5H2O) to peat, Pinus radiata bark and composted sawdust. It look ∼4 days for extractable Cu levels to stabilize after Cu had been added to the substrates.Chrysanthemum morifolium cultivar ‘Yellow Mandalay’ had chlorotic leaves and reduced vegetative growth, when grown in media comprised mainly of composted Eucalyptus marginata sawdust, if saturation extracts containing DTPA and 2 mM DTPA (1:1.5 by volume) extracts of the media contained less than ∼1 and 0.25 mg l−1 Cu, respectively. However, under the conditions of this experiment, maximum reproductive growth was possible only if the extracts contained at least ∼ 11.7 and 5.1 mg l−1 Cu, respectively. The results suggest that additions of Cu to soil-less media to be used for growing flowering plants should be higher than when only vegetative growth is needed, and should be in the range 10–20 mg l−1. Critical Cu concentrations in bulked leaves associated with optimum vegetative and reproductive growth were 2.4 and 10.3 mg kg−1, respectively.
Analysis of the salt and nutrient status of potting composts and growing substrates with the aid of the 1:25 weight extract ‐ previously used in the Netherlands ‐ has several disadvantages. The interpretation of analytical data based on the organic matter content is not very accurate because this content does not provide a true estimation of the moisture capacity. In addition the conductivity of growing media rich in gypsum gives an unfavourable impression of the salt status.Very good results were obtained in an investigation at the research station at Naaldwijk with a 1:1½ volume extract. For the preparation of this extract potting composts and growing substrates were standardised as regards moisture content, after which one part by volume was measured and mixed with 1½ parts of water. The conductivity of the extract and the contents of chloride, nitrogen, nitrate, ammonium, phosphate, potassium and magnesium were determined. The analytical results were closely correlated with those of the soil solution. The correlation coefficients were between 0.957 and 0.986. The data obtained for the 1:25 weight extract were not as closely correlated with those of the soil solution; the correlation coefficients varied between 0.775 and 0.980.The weight ratio water : soil of the 1 s 1½ volume suspension was closely correlated with the moisture content at pF 1.5. In the case of growing media with low moisture capacity the ratio was about 3:1 and with high moisture capacity about 30:1.