Evaluation of efficient soil test methods for Zn and their critical vales in salt‐affects soils for rice

Abstract

Soil pot culture experiment was conducted on 22 soils of Balewal‐Phaguwala‐Narike (BPN) and 24 soils of Isri‐Langrian‐Narike (ILN) associations using rice (PR 106) as test crop at 0 and 7.5 ppm Zn levels. Chelating extractants 0.005M DTPA, 0.01M EDTA‐(NH₄)₂CO₃ and 0.05M EDTA, extracted more soil Zn than double‐acid and were significantly correlated with each other as well as with soil pH and clay in BPN and only with clay in ILN soil association. Soil CaCO₃ governed the double‐acid extractable Zn in these soils. Dry matter yield and Zn uptake by rice significantly increased with 7.5 ppm Zn application. The response was higher in ILN than BPN soil association, The DTPA method gave the highest correlation with Bray's yield and Zn uptake (r =0.72 and 0.55) followed by 0.05M EDTA (r ‐ 0.75 and 0.61) or EDTA‐(NH₄)₂CO₃ (r =0.70 and 0.61). The predictability of rice yield improved from 18–27 to 27–35, 32–43, 34–44 and 51–55 percent as a result of stepwise inclusion of pH, CaCO₃, organic carbon (OC) and clay respectively in the regression equation alongwith Zn extracted by chelating agents.

The critical levels of DTPA, EDTA‐(NH₄)₂CO₃ and EDTA extractable Zn significantly differed in the two associations and were 0.69, 0.82 and 1.24 ppm in BPN and O.BC, 1.09 and 1.42 ppm in ILN soil association. Soil properties further affected the critical levels. This for DTPA available Zn was 0.80 and 1.03 ppm in soil containing less and greater than 2% CaCO₃, 1.03 and 0.80 ppm in soils containing less and greater than 0.25% OC. These values for EDTA‐(NH₄)₂CO₃ available Zn were 1.09 and 0.91 ppm Zn in soils containing less and greater than 15% clay suggesting that critical levels of Zn for each category of soil properties should be considered while making recommendations of Zn fertilization of crops.,     

Use of routine soil tests in predicting corn leaf zinc

Abstract

Zinc of index corn leaves samples from 91 Minnesota sites on numerous soil types was correlated with soil Zn extracted by four routine procedures. The EDTA?(NH₄)₂CO₃ ‐ extractable soil Zn was more closely correlated with leaf Zn than soil zinc extracted by 0.1N HCl, EDTA‐NH₄OAc, or by NH₄OAc ‐ dithizone. Soil pH, CaCO₃ equivalent, extractable P, and organic matter of both acid and calcareous soils were negatively correlated with leaf Zn. When EDTA ? (NH₄)₂CO₃ ‐ extractable Zn was included with routine soil tests, a prediction equation for corn leaf Zn was formulated and compared with analytical values. However, the use of 1.4 ppm EDTA ? (NH₃)₂CO₃, ‐ extractable soil Zn alone as a critical value was equally effective in predicting leaf Zn.     

Extractability of previously‐applied zinc as influenced by properties of calcareous soils

Abstract

The recovery of applied zinc (Zn) by plants is relatively small. Coupled with lack of leaching, this leads to accumulation of Zn in topsoil which may result in unfavorable growth conditions for the subsequent plants. Different extractants may be used for assessing the Zn status of soils previously treated with Zn sources. The extractability of retained Zn is influenced by soil properties. This experiment was conducted to study the influence of selected properties of calcareous soils on extractability of Zn by three popular Zn soil tests. Twenty samples from surface horizons (0–20 cm) of highly calcareous soils of southern Iran (pH 7.9 to 8.5; calcium carbonate equivalent 16 to 58%) previously treated with three levels of Zn (0, 10, and 20 mg Zn kg^‐1 soil as ZnSO₄#lb7H₂O) in triplicate and under one crop of corn (Zea mays L.) were extracted with DTPA, EDTA‐(NH₄)₂CO₃ and Na₂‐EDTA. Extractability (EXT) in a particular extractant was defined as the slope of the regression line, relating extractable Zn of each soil to the rate of applied Zn, multiplied by 100. The EXT values of soils ranged from 24.9 to 73.0% for DTPA, 47.2 to 84.4% for EDTA‐(NH₄)₂CO₃, and 28.2 to 56.7% for Na₂‐EDTA. Stepwise regression equations showed that cation exchange capacity (CEC) and calcium carbonate equivalent (CCE) followed by clay content were the most influential soil properties in EXT of retained Zn of highly calcareous soils. The EXT values decreased with increase in CEC, and CCE but increased with increase in clay.     

Soil micronutrient contents and relation to other soil properties in Ethiopia

Abstract

Alfisols, Vertisols, Inceptisols, Aridisols, Mollisols, and Entisols were sampled (0–30 cm) from 32 locations across Ethiopia. The soils were analyzed for copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) contents using 0.005 M diethylene triamine pentaacetic acid (DTPA), 0.05 M hydrochloric acid (HC1), and 0.02 M ethylene diamine tetraacetic acid (EDTA) extractants. EDTA extracted more of each micronutrient than DTPA, which extracted greater amounts than HC1. The quantities of EDTA and DTPA‐extractable micronutrients were significantly correlated, and were in the order: Mn>Fe>Cu>Zn. The order of HCl‐extractable micronutrients was Mn>Fe>Zn>Cu. Micronutrient contents of Mollisols, Vertisols, and Alfisols were usually greater than those of the other soils, and Entisols usually had the lowest micronutrient contents. The contents were mostly positively correlated with clay and Fe₂O₃ contents, but negatively correlated with soil pH and A1₂O₃contents. While comparison of DTPA‐ and EDTA‐extractable micronutrients with critical levels showed that most soils had adequate amounts of the micronutrients for crops, the amounts extracted by HC1 were below critical levels in most soils. Since the critical levels that were used in the comparisons were not established in Ethiopia, calibration of the soil contents of these micronutrients with crops grown in Ethiopia is required to identify the most suitable extractant(s).     

Verhalten von Schwermetallen in Böden 1. Untersuchungen zur Schwermetallmobilität

Behaviour of heavy metals in soils. 1. Heavy metal mobility 158 soil samples with widely varying composition were analysed for their total, EDTA, DTPA and CaCl₂ extractable contents of Cd, Zn, Mn, Cu and Pb. By means of single and multiple regressions the relations between the different heavy metal fractions and the pH, organic carbon and clay content were considered. The correlations between the total, EDTA and DTPA extractable contents are very close, whereas the CaCl₂ extractable contents are not or only weakly correlated with these fractions. According to these statistical results the former fractions are considered to be the total quantity (total content) and the reactive quantity (EDTA and DTPA extractable contents) of the heavy metals, whereas the CaCl₂ extractable fraction represents the mobile fraction of the heavy metals in soils. The multiple regressions show that the mobile content of heavy metals is closely correlated with each of the quantity fractions and with soil pH. In the same way the proportion of the mobile fraction (in %) of the total, EDTA and DTPA extractable heavy metal content of the soil samples is closely related to the soil pH. Hereby the proportion of the mobile content of the various elements increases in the pH range 6,5 - 3 below element-specific threshold pH values (in brackets) in the order Cd (6,5) > Mn (5,7) > Zn (5,3) > Cu (4,5) > Pb (3,5). In the pH range 6,5 - 7,5 mainly Cu and to a lesser degree also Pb show an increasing mobility due to the influence of soluble organic substances.     

The profile distribution of total and extractable copper in selected Nigerian soils

Abstract

The profile distribution of total, DTPA‐ and 0.1N HCl‐extractable Cu was determined in 11 Nigerian soil profiles formed from various parent materials including the coastal plain sands, shales, basalt, granite and banded gneiss.

Total Cu ranged from 7 to 72 ppm with a mean of 35 ppm₀ The soils formed from basalt had the highest values while those on coastal plains had the least content. Generally, there was a higher content in the subsoils than in the surface horizons. The total Cu significantly correlated with percent clay and the free oxide contents of Fe and Mn.

DTPA ‐ and 0.1N HCl‐extractable Cu ranged from 0.08 to 2.81 ppm and 0.10 to 7.78 ppm, respectively. Soils on metamorphic rocks gave the highest values of DTPA‐extractable Cu. The DTPA‐extractable Cu ‐was only related to pH but the acid extractable Cu was associated with total Cu, clay, free Fe₂O₃ and MnO₂ contents.     

Investigation of relationships between iron status of peach leaves and soil properties

This study investigated those soil factors related to iron (Fe) chlorosis between Fe status of peach leaves and some soil properties in the Antalya region of Turkey. The total Fe content of leaves was negatively correlated with soil pH and the organic matter content of the soils. Extractable Fe (by 1N HCl) was negatively correlated with the calcium carbonate (CaCO₃) and bicarbonate (HCO₃‐) content of the soils. In addition, both total‐ and extractable‐Fe contents of leaves were also negatively correlated with the copper (Cu) content of the soils. On the other hand, significant correlations were found among the Fe index, P/Fe ratio of leaves, and soil pH, phosphorus (P), zinc (Zn), and Cu content of the soils. It appears from these studies that high pH, and the CaCO₃, HCO₃‐, and Cu contents are effective soil factors affecting the availability of Fe and its uptake by the peach trees, and these soil factors were associated with severity of Fe chlorosis in the studied area.     

Labile pools of copper and zinc in calcareous soils as measured by DTPA and plant extraction

Abstract

Labile pools of Cu and Zn were measured on two calcareous soils from Saudi Arabia, using successive extraction with DTPA, and successive cropping followed by extraction with DTPA after cropping. The examined soils differed in their ability to supply Cu and Zn. The first DTPA extraction removed a major proportion of the labile pool, particularly in the sandy soil. The two soils showed a general decrease in extractable Cu and Zn with progressive extractions, with DTPA extractable Cu declining more rapidly than Zn. DTPA extractable Cu and Zn determined after cropping were highly correlated with DTPA extractable Cu and Zn values obtained after successive extractions. The results gave evidence on both the contribution of element dissolution from insoluble forms with progressive extraction or cropping, and the usefulness of the DTPA extractant for monitoring the availability of Cu and Zn in these calcareous soils.     

Micronutrients distribution in salt-affected soils of the Punjab in relation to soil properties

Salt-affected soils in arid and semi-arid tracts of the Indian Punjab are prone to deficiency of micronutrients. Nine profiles from alluvial terraces, sand dunes and palaeochannels in the southwestern Punjab were investigated for total and diethylenetriamine-penta-acetic acid (DTPA) extractable Zn, Cu, Mn and Fe. Soil physiography exerted significant influence on the spatial distribution of micronutrients. Total contents varied from 20–78 for Zn, 8–32 for Cu, and 88–466 mg kg^?1 for Mn and 0.82–2.53% for Fe. DTPA-extractable contents varied from 0.10–0.98 for Zn, 0.14–1.02 for Cu, 0.54–13.02 for Fe and 0.82–9.4 mg kg^?1 for Mn. Total contents were higher in fine-textured soil than in coarse-textured soils. Concentration of micronutrients in the surface layer was low and there occurred more accumulation in the Cambic horizon. Organic carbon, pH, clay, silt and calcium carbonate exerted strong influence on the distribution of micronutrients. DTPA extractable Zn, Cu, Mn and Fe increased with increasing organic carbon but decreased with increase in pH and calcium carbonate content. Total micronutrient contents increased with increase in clay, silt and calcium carbonate contents and decreased with increase in sand content.     

Micronutrient status of calcareous paddy soils and rice products: implication for human health

Modern agricultural systems have to provide enough micronutrient output to meet all the nutritional needs of people. Accordingly, knowledge on micronutrient status in soil and crop edible tissues is necessary. This study was carried out to investigate zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu) concentration of calcareous paddy soil and the relative rice grain. Rice crops (straw, hull, and grain) and associated surface soils (0–25 cm) were collected from 136 fields and analyzed for total and diethylene triamine pentaacetic acid (DTPA) available Zn, Fe, Mn, and Cu. The DTPA-Zn concentration in more than 50% of paddy soils was less than its critical deficiency concentration (2 mg kg⁻¹), while the concentrations of DTPA Fe, Mn, and Cu were sufficient. The grain Zn concentration of more than 54% of the rice samples was less than 20 mg kg⁻¹. About 55% and 49% of the rice samples were deficient in Mn and Cu, respectively, while the Fe concentration in rice grains was sufficient. A significant negative correlation was found between the CaCO₃ content and soil DTPA-extractable Zn, Fe, Mn, and Cu. There were significant relationships between the total soil phosphorus and DTPA-extractable micronutrient concentrations. By considering the average daily rice consumption of 110 g per capita, the Zn, Fe, Mn, and Cu intake from rice consumption was estimated to be 2.4, 7.7, 1.6, and 0.7 mg for adults, respectively.     

酸化及施碳酸钙对土壤各形态锰的影响

以灰潮土为对照 ,研究了华中地区 3种已明显发生酸化的土壤在施用碳酸钙前后各形态锰的变化情况。结果表明 ,已酸化的红壤、棕红壤和黄褐土施用碳酸钙降低了土壤酸度 ,土壤交换态锰随 pH值上升而降低 ,其降幅分别为 42 % ,49%和 39% ;其它形态锰的增减随各土而异 ,残留态锰较稳定 ,变幅小。作为对照 ,灰潮土虽与前 3种已酸化土壤一样种植过多茬作物 ,但其交换态锰含量仍甚微。无论是否施用碳酸钙 ,在灰潮土的交换态锰、碳酸钙结合态锰和易还原态锰 3种形态锰中 ,易还原态锰占 80 %以上 ,说明易还原态锰是其活性锰的主要部分     

Removal of Heavy Metals from Calcareous Contaminated Soils by EDTA Leaching

The performance of EDTA for the treatment of calcareous soils contaminated with heavy metals from mining and smelting activities was evaluated in this study. Soil samples containing variable levels of contamination, from 500 to 35 000 mg kg^-1 Pb and 700 to 20 000 mg kg^-1 Zn, were subjected to EDTA treatment and the extraction of heavy metals was found to vary, ranging between 50 and 98% for Pb and 50 to 100% for Zn. Total residual concentrations were above the limits set by regulatory authorities; leachable metals, however, were efficiently removed and treated soils were all acceptable in terms of toxicity. The effect of EDTA concentration and pulp density was studied on a soil sample containing 12 000 mg kg^-1 Pb and 10 000 mg kg^-1 Zn. Heavy metals removal was improved at low pulp densities and when EDTA concentration was increased from 0.025 to 0.25 M. The tetrasodium salt Na₄-EDTA was found to be less effective for metals removal compared to the disodium salt Na₂-EDTA, though applied at higher concentrations. This experimental work has also demonstrated the great importance of soil matrix for the overall evaluation of the EDTA leaching as a cost effective remedial option. The simultaneous dissolution of calcite was found to consume approximately 90% of the available EDTA. It was thus concluded that for the treatment of calcareous soils the design criteria and cost estimations should be based on the calcite content of the soil.     

Prediction of residual effects of zinc sulfate on growth and zinc uptake of corn plants using three zinc soil tests

Abstract

A significant portion of chemical zinc (Zn) fertilizers applied to calcareous soils is not absorbed by the first crop and may, therefore, affect the growth and chemical composition of the subsequent crops. This is called the residual effect of Zn. Soil tests may be used to predict such effects. The present experiment was conducted to study the residual effects of zinc sulfate (ZnSO₄) on the second crop of corn (Zea mays L.) grown on selected highly calcareous soils of Iran and to compare the suitability of three soil tests for prediction of the effects. Twenty highly calcareous soils of southern Iran (16–58% calcium carbonate equivalent; pH 7.9–8.5), previously treated with three levels of Zn (0, 10, and 20 mg Zn/kg as ZnSO₄) and under one crop of corn, was used in greenhouse to grow a second crop of corn without additional Zn fertilizer but with uniform application of nitrogen (N), phosphorus (P), and iron (Fe). Soils were sampled before the second crop and extracted with three Zn extradants, DTPA, EDTA‐(NH₄)₂CO₃, and EDTA. Dry weight of plant tops and Zn concentration and uptake after eight weeks under the greenhouse conditions were used as the plant responses to residual Zn. Statistical analyses including F‐test and multiple regression equations showed that the overall effect of previously‐applied Zn on dry matter was nonsignificant, but Zn concentration and uptake were significantly increased. The three soil tests predicted the Zn concentration and uptake equally well. Moreover, DTPA and EDTA soil tests could predict the dry matter of plants at the highest level of previuosly‐applied Zn (20 mg Zn/kg), especially when selected chemical properties of soil, namely, calcium carbonate equivalent or organic matter content, were considered in the regression equations.     

The effect of EDTA on the extractability of Zinc (Zn), Cadmium (Cd) and Nickel (Ni) in Vertisol and Alluvial soils

Ethylendiamintetraacetic acid (EDTA) is persistent in the environment. The presence of EDTA in soil may alter the mobility and transport of Zn, Cd and Ni in soils because of the formation of water soluble chelates, thus increasing the potential for metal pollution of natural waters. Mobility of metals is related to their extractability. To investigate metal extractability affected by EDTA, Zn, Cd and Ni were added to Vertisol and Alluvial soil at rates of 50, 2 and 5 mg kg^-1, respectively. Both natural and metal amended soils were treated with Na₂EDTA at rates of 0; 0.2 and 0.5 mg kg^-1. After five months of incubation soil samples were extracted with 0.1 N HCl, 0.005 M DTPA + 0.01 M CaCl₂ + 0.1 M TEA (0.005 M Diethylenetriaminepentaacetic acid + 0.01 M Calcium cloride + 0.1 M Triethanolamine) and 1 M Mg(NO₃)₂, the latter of which extracts the exchangeable from of metald (Zn, Cd and Ni).

According to experiment results, Zn, Cd and Ni in all extraction increased with increasing rates of EDTA in the natural and metal amended soils.     

Evaluation of soil extractants to estimate available micronutrients under wheat‐field conditions

Abstract

Three extracting reagents were evaluated by correlation analyses to provide the best index of Zn, Cu, Mn and Fe availability to wheat (Triticum aestivum L.) plants growing under open field conditions. Twenty one soils were selected to obtain the widest range in properties of soils of the land wheat cultivated. The magnitude of the extractive power varied in the following order: 6NHCl ? EDTA + NH₄OA_C, pH4.65 > DTPA‐TEA, pH 7.3. The mild extractants, EDTA and DTPA, gave the same order of removal of micronutrients being Zn < Cu < Fe < Mn. The acid extractant was on the contrast more effective on Cu and Fe with respect to Zn and Mn, respectively. Wheat concentrations of Zn, Mn and Fe were significantly correlated to soil micronutrients. Highly significant relationships were found for Zn extracted by DTPA solution (r = 0.737***) and for Mn and Fe extracted by EDTA solution (r = 0.710*** and r = 0.564**). Plant Zn and Mn were also well predicted by the acid extraction. The absence of correlation for plant Cu vs. soil Cu occurred probably because of wheat concentrations almost constant, ranging from 5.0 to 8.0 mg/kg.     

Comparison of four extractants and chemical fractions for assessing available zinc and copper in soils of India

Abstract

Relative suitability of different extraction procedures for estimating available zinc (Zn) and copper (Cu) in soils was assessed using DTPA, 0.1 N HCl, ammonium acetate+EDTA, and double acid (HCl+ H₂SO₄) as extractants and rice as a test crop in Neubauer experiment. The relationships between Zn concentration and uptake of Zn by rice plants and Zn extracted by the different methods showed that DTPA‐TEA, pH 7.3, could very suitably be used to assess Zn availability in soils. However, 0.1 N HCl was better for assessing the Cu availability in soils to the rice plants. Water‐soluble and exchangeable fractions of Zn and Cu had significant positive correlations with Zn and Cu concentrations, respectively obtained by all the four extractants tested. The results also showed that DTPA and ammonium acetate+EDTA extracted organically bound Zn, whereas DTPA, 0.1 N HCl and ammonium acetate+EDTA extracted organically bound Cu. Water‐soluble, exchangeable and organic matter bound fractions exhibited significant relationships with Zn and Cu concentrations, their uptake and rice dry matter yield.     

上海土壤中微量元素的含量与分布的研究

植物必需的微量营养元素锌、锰、钼、硼、铜在土壤中供给不足或过剩时,都可能引起植物、动物及人体生理功能失调,生长发育受阻,诱发出各种特殊的生理病害。明确土壤中微量元素含量分布规律及其有效性问题,有助于采取措施来调剂微量元素的供应水平,对于农业生产的发展,以及维护人类和动物的健康,都具有重要的意义。本文就1978-1979年关于上海土壤中微量元素的含量分布及其有效性问题的研究,作一总结。     

Etude de la nutrition potassique du sorgho II‐ incidence du remplacement du potassium par le sodium sur la teneur en acides organiques des feuilles

Abstract

An Investigation was conducted to determine the content and distribution of total and DTPA‐extractable Zn in the genetic horizons of 72 agriculturally important soils from the six major mineral soil areas in Louisiana.

The concentration of total Zn appeared to vary more with the clay constituents of the soils and the amount of the element in the parent materials than with soil depth. The majority of the soils had the largest amounts of total Zn in the subsurface horizons. The range in total Zn for all soils and horizons was from 7.0 to 150.0 ppm.

The DTPA‐extractable Zn in all of the soils and horizons ranged from 0.08 to 4.22 ppm. In the majority of the soil profiles the highest concentration of extractable Zn was in the surface horizons. There was a decrease in the extractable Zn with increasing soil depth. The alluvial soils along the Ouachita and Mississippi Rivers, and the Mississippi Terrace soil areas contained relatively large amounts of DTPA‐extractable Zn.

In some soils the extractable Zn significantly correlated with total Zn. There was also a close relationship between extractable Zn and organic matter content, especially in the Ap horizons.     

Removal of trace and major metals by soil washing with Na<Subscript>2</Subscript>EDTA and oxalate

Background, aim, and scope  

Various metals such as cationic metals (Cu, Pb, Zn) and anionic metals (As, Cr) often coexist in real soils, and normal soil washing techniques for the removal of cationic metals with a single-washing reagent make it rather difficult to simultaneously remove all of them. Oxalate could effectively remove anionic As and EDTA could effectively remove the cationic metals, so it was possible to remove all coexisting cationic and anionic metals by washing with the combination of Na₂EDTA and oxalate. The objective of this study was to (1) discuss the possibility of removing five metals, As, Cd, Cu, Pb, and Zn, effectively from the soil by washing with Na₂EDTA-combined oxalate; (2) optimized through the consecutive washing.