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.     

Determination of mobile heavy metal fraction in soil: Results of a pot experiment with sewage sludge

Abstract

The development of a method using a chelating resin to assess heavy metal mobility in soil and the first results obtained from a pot experiment with sewage sludge additions were studied. The resin was Chelex 100 with the calcium (Ca)‐form of the resin proving to be best suited for the extraction. The efficiency of recovery of the heavy metals from an aqueous solution ranged from 81.2% for cadmium (Cd) to 102% for copper (Cu) within 24 hours. For heavy metal extractions from a soil sample, a 96 hour extraction period was found to be optimum. The extracted heavy metal portion was comparable with the results obtained with an ammonium acetate (NH₄AOc) extraction. Total heavy metal contents in the substrate of the pot experiment did not show a significant influence due to the sewage sludge treatments, although considerable amounts of heavy metals were added by the sewage sludge. This effect can be both due to the incomplete recovery of heavy metals by an aqua regia extraction and leaching losses of these elements from the pots. Rape (Raphanus sativus L.) plants did not have any heavy metal contents which might indicate a high availability in soil, with the Cd and Cr contents in the rape biomass being partly lower in the sewage sludge‐treated pots than in the control plants; however, zinc (Zn) uptake slightly increased with increasing sewage sludge treatments. The Chelex 100 extraction procedure was correlated with Cd plant uptake, while the NH₄AOc extraction procedure was better related to the Zn uptake by rape plants.     

A comparative evaluation of the Mississippi soil test method for determining available manganese,magnesium, and calcium

Abstract

Soil Samples (72) were collected from the Delta, Hill, and Northeast Blackland areas of Mississippi. Chemical analyses for manganese, magnesium, and calcium were made using the Mississippi Soil Test Solution (MSTS) and several other extracting solutions chosen for comparison. For the determination of available soil manganese, the MSTS proved to be as effective as either the Double Acid (0.025 N HCl in 0.05 N H₂SO₄) or 0.1 N H₃PO₄. The acid extractants removed more manganese than 1 N NH₄OAc (pH 7.0) and therefore included forms that are not exchangeable. The methods studied for magnesium determinations were equilibrium extraction with 1 N NH₄OAc, MSTS, Double Acid, 0.25 N CaCl₂, and leaching with 1 N NH₄OAc. All methods were highly correlated and therefore would be equally effective in determining available soil magnesium. Since MSTS and equilibrium extraction with 1 N NH₄OAc removed similar amounts of magnesium from the soil, the same calibration can be used. Calcium determinations were made using equilibrium extraction with 1 N NH₄OAc, MSTS, and Double Acid, and by leaching with 1 N NH₄OAc. All methods proved effective in measuring available soil calcium on acid soils.     

Influence of residual phosphate fertilizer on labile and extractable zinc in hawaii soils

Abstract

Zinc availability was studied using five soils from Hawaii which had histories of massive phosphorus applications. Heavy phosphate fertilization usually increased extractable Zn, irrespective of the extractant used. The extra extractable Zn associated with the added P probably came from Zn as an accessory element in the fertilizer. Treble superphosphate commonly used in Hawaii contains about 1400 ppm Zn. The Zn content of phosphate fertilizers must be considered before making statements about the effect of fertilizer P on Zn solubility and availability in soils.

Two solutions (0.1N HCl and 0.005M DTPA) were compared as Zn extractants for Hawaii soils. DTPA extracted less Zn than 0.1N HCl. Zinc extracted by repeated HCl treatment was more closely related to the labile Zn pool (E‐values and L‐values) than was DTPA‐extractable Zn. The results suggest that 0.1N HCl extractable Zn, Zn E‐value and Zn L‐value measured the quantity of a single fraction of soil Zn.

Repeated extraction of soil with 0.1N HCl seems to be a suitable procedure for evaluating the Zn status of acid, highly weathered soils of Hawaii.     

A turbidimetric method for determining phosphate‐extractable sulfates in tropical soils

Abstract

Turbidimetric methods, using Ba ions to precipitate SO₄, are frequently used to determine soil sulfates extracted with phosphate solutions. These methods, as routinely performed, seriously underestimate SO₄ in some soils of the tropics because phosphate is removed from the extractant by soil adsorption and because many extracts fail to yield satisfactory precipitate even if the extracting procedure is adequate. Decolorizing the extracts with carbon black, treating extracts with strong oxidizing agents, adding SO₄ spikes, and seeding the extracts with BaCl₂ seed‐crystals improve precision, but some extracts, especially those from soils derived from volcanic ash, do not yield reliable precipitates even though these procedures are employed. This paper presents a method that consistanlty yielded more SO₄ than other turbidimetric procedures with which it was compared. The proposed method was further validated against an ion‐chromatographic method for SO₄ determination. The two methods yielded virtually identical results.

The proposed method consists of extracting SO₄ with 0.04 M Ca(H₂PO₄)₂ pH 4, at a soil‐to‐solution ratio of 1: 10. Repeated extraction is necessary for phosphate‐retentive soils. (A. single extraction was approximately 40% effective for removing indigenous SO₄ from a Hydric Dystrandept subsoil, approximately 78% effective for an Eutrustox.) Organic materials are removed from the extracts by adsorption on charcoal; SO₄ is concentrated in the extract by volume reduction; a SO₄ spike is added; BaCl₂‐seed crystal is added, after which volume is increased by adding BaCl₂ solution. Optical density is read at 600 nm.     

Estimation of critical limit for zinc in rice soils

Abstract

Twenty surface soil samples were collected from Nainital Tarai (foothills of Himalya) where “Khaira”; disease (Zn deficiency of rice) is prevalent. Rice (Oryza sativa L. variety IR‐8) was grown in pots for 8 weeks after transplanting. Experiments were conducted to determine the suitability of five soil Zn extractants: dilute acid (HCl + H₂SO₄) mixture; DTPA‐(NH₄) ₂CO₃, pH 7.3; dithizone; NH₄OAc, pH 4.6; and 2N MgCl₂ to predict Zn deficiency. Critical values for soil available Zn were established for rice by the old and new Cate and Nelson procedures¹.

Zinc extracted from the soils with dithizone; NH₄OAc, pH 4.6; 0.2N MgCl₂. and DTPA‐(NH₄) ₂CO₃ pH 7.3 was significantly correlated with the uptake of Zn by the rice plants. The correlation between Zn extracted with the dilute acid (HCl + H₂SO₄) mixture and plant Zn was not statistically significant. The ex‐tractants which extracted greater quantities of Zn gave higher critical values and vice versa. It is concluded that all extracting solutions except the dilute acid (HCl + H₂SO₄) mixture were found to he suitable for predicting available Zn in rice soils of Tarai.     

Applied Mn extracted by four methods correlated with Mn concentrations in soybean leaf tissue on a southeastern soil

Abstract

Four extractants for soil Mn were compared for their sensitivity to changes in Mn availability caused by rates and sources of added soil Mn and soil pH variations. Their ability to extract amounts of Mn correlated with plant Mn concentrations was also determined. Two field experiments were conducted on a sandy, high water table soil (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) which included 5 Mn rates, 4 Mn sources and 3 soil pH levels. Soybeans [Glycine max (L.) Merr. cultivar Ransom] were grown and leaf tissue and soils sampled at the late pod‐fill stage. All four extractants separated the high‐ Mn rates, but the small exchange method did not separate the low Mn rates. Few differences were observed among extractants due to Ma sources. The DTPA method was the only procedure to correctly distinguish soil pH levels by showing decreasing extractable Ma with increasing soil pH. Including pH in multiple regressions significantly increased the plant Mn‐soil Mn correlation coefficients. The DTPA method and the 0.1N H₃PO₄ method had the highest correlation coefficients and the double acid method the lowest. The small exchange method was intermediate. Considering all the results, the DTPA was the most promising method for extracting Mn from this sandy, southern Coastal Plain soil.     

Estimation of critical limit for zinc in rice soils

Abstract

Twenty surface soil samples wore collectod from Nalnltal Tarai (foot‐ hills of Himalya) where ‘Khaira’ disease (Zn deficiency disease of rice) was prevalent. Rice (Oryza sativa L. variety IR ‐ 8) was grown in pots for 8 weeks after transplanting. Experiments were carried out to find the suitability of five soil Zn extractants viz. dilute acid (HC1 ‐ H₂SO₄) mixture, DTPA‐ (NH₄) ₂CO₃, pH 7.3, dithizono, NH₄ ‐ Ac, pH 4.6 and MgCl₂. Critical limits of available Zn in soils were established for rice crop by old and new Cate and Nelson procedures.

Zn extracted from the soil with NH₄ ‐ Ac, pH 4.6, dithlzono, MgCl₂, and DTPA‐(NH₄) ₂CO₃, pH 7.3 was significantly correlated with the uptake of Zn by the rice plants. The correlation of Zn uptake with dilute acid mixture extractable Zn was not significant. The extractant which extracted more Zn gave higher values of critical limit and vice versa. It is concluded that all extracting solutions except dilute acid mixture were found to be suitable for predicting available Zn in rice soils of Taral.     

Effect of Zinc Humate on Growth of Soybean and Wheat in Zinc‐Deficient Calcareous Soil

Abstract

Humic acids have many benefits for plant growth and development, and these effects may be maximized if these materials are combined with micronutrient applications. In the present study, pot experiments were conducted to evaluate the effects of zinc (Zn) humate and ZnSO₄ on growth of wheat and soybean in a severely Zn‐deficient calcareous soil (DTPA‐Zn: 0.10 mg kg^?1 soil). Plants were grown for 24 (wheat) and 28 days (soybean) with 0 or 5 mg kg^?1 of Zn as either ZnSO₄ or Zn humate. Zinc humate used in the experiments was obtained from Humintech GmbH, Germany, and contained 5% of Zn. When Zn was not supplied, plants rapidly developed visible symptoms of Zn deficiency (e.g., chlorosis and brown patches on young leaves in soybean and necrotic patches on middle‐aged leaves in wheat). Adding Zn humate eliminated Zn‐deficiency symptoms and enhanced dry matter production by 50% in soybean and 120% in wheat. Zinc‐humate and ZnSO₄ were similarly effective in increasing dry matter production in wheat; but Zn humate increased soybean dry matter more than ZnSO₄. When Zn was not supplied, Zn concentrations were 6 mg kg^?1 for wheat and 8 mg kg^?1 for soybean. Application of Zn humate and ZnSO₄ increased shoot Zn concentration of plants to 36 and 34 mg kg^?1 in wheat and to 13 and 18 mg kg^?1 in soybean, respectively. The results indicate that soybean and wheat plants can efficiently utilize Zn chelated to humic acid in calcareous soils, and this utilization is comparable to the utilization of Zn from ZnSO₄. Under Zn‐deficient soil conditions, plant growth and yield can be maximized by the combined positive effects of Zn and humic acids.     

Soil nitrogen fractions as influenced by sample preparation and extraction

Abstract

In order to evaluate the influence of extraction procedure on extractable nitrogen (N) fractions, fresh as well as dried soil samples were extracted with CaCl₂ at various temperatures (20,40,60, 80°C) for 30–120 minutes. Data obtained were compared with those from the electro‐ultra‐filtration (EUF) method. Increasing the drying temperature as well as the extraction temperature led to an increase in N_org content. The EUF and CaCl₂‐method produced comparable results for all N‐fractions (NO₃ ^‐, NH₄ ⁺, N_org) when an extraction temperature of 80°C was applied for two hours. Data presented suggested that the N_org fraction represented mainly the microbial biomass and may thus be considered as being easily available to plants.     

Evaluation of lime requirement methods for Delaware soils

Abstract

Rapid, accurate identification of the lime required to attain a desired pH is essential for the coarse‐textured soils of the Atlantic coastal plain to avoid micronutrient deficiencies (Mn, Zn) in sensitive crops and to insure herbicide efficacy. The University of Delaware Soil Testing laboratory is one of only seven of the 25 states in the Northeastern and Southern regions that does not use a buffer solution to make lime requirement determinations. The present method bases lime recommendations on soil pH in water, combined with an estimate of buffering capacity obtained by hand texturing soils. This approach is time‐consuming and includes the potential for considerable operator variability in obtaining the textural estimate. A study was initiated to compare four buffer solutions (Adams‐Evans, Mehlich, SMP‐single buffer, SMP‐double buffer) with the current approach and the actual lime requirement as determined by incubation of 19 Delaware soils with six rates of CaCO₃ for six months. Soil pH effects on Mn and Zn availability were determined by extraction of all samples from the incubation study with the Mehlich I (.05M HCl + .0125M H₂SO4) soil testing solution. Results indicated that organic matter was the primary soil component responsible for pH buffering in Delaware soils, and that the Adams‐Evans or Mehlich buffers were the best predictors of actual lime requirement. The appropriate target pH range for the coarse‐textured soils of Delaware, based on Mn and Zn availability, was determined to be 5.5–6.0. Liming soils to pH values greater than 6.0 is, for most crops, unnecessary and will reduce Mn availability below critical levels for sensitive crops such as soybeans and small grains.     

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.     

Conductimetric determination of soil urease activity

Abstract

A fast and sensitive method to determine urease activity in soils is described. It involves extraction of NH₄‐N with 1 N. KC1 : 0.01 N HC1 and measurement of NH₄ concentration by electroconductivity using a steady state flow system across a membrane. Sampling was done directly from the extracts with an automatic sampler at 40 samples per hour. The detection limit for NH₄‐N was below 0.05 ppm in the extract. Extracts could be stored at room temperature for 17 hours before measuring NH₄. No post‐treatment hydrolysis of urea occured.     

Response of corn to plowed‐down and disked‐in Zn as zinc sulfate

Abstract

A field investigation was conducted to compare the efficacy of plowed‐down and disked‐in Zn as ZnSO₄.H₂O in correcting Zn deficiency of corn (Zea mays L.). The soil, Buchanan fine sandy loam, was nearneutral in pH and contained 0.7 ppm of EDTA‐extractable Zn and 1.4 ppm of dilute HCl‐H₂SO₄ extractable P. Application of 6.72 kg Zn/ha as ZnSO₄.H₂O corrected Zn deficiency of corn plants on the soil. Corn grain yields and Zn concentrations in tissue samples indicated that the plowed‐down and disked‐in Zn were about equally effective in correcting Zn deficiency where the level of Zn application was 6.72 kg/ha.     

Comparison of soil zinc extractants for detection of applied zinc and prediction of leaf zinc concentration

Abstract

Many soil extractants have been developed for determination of zinc (Zn) availability to plants. The optimum soil Zn extractant should be useful not only for prediction of plant Zn concentration but also for detection of applied Zn levels. The objectives of this study were: i) to compare soil Zn extradants for detecting applied Zn and for predicting peanut leaf Zn over a range of soil pH levels, and ii) to correlate other soil‐extractable Zn levels with Mehlich‐1. Soil and peanut leaf samples were taken from a field study testing pH levels as the main plots and Zn application rates in the sub‐plots. Extractable Zn was determined on soil samples using Mehlich‐1, Mehlich‐3, DTPA, MgNO₃, and many dilute salt extradants of varied strength and pH. Correlation of extractable soil Zn to cumulative applied Zn levels revealed Mehlich‐1, Mehlich‐3, DTPA, and AlCl₃ extradants to be among the best indicators of applied Zn. Leaf Zn concentration was best correlated with soil Zn extracted by dilute salts, such as KCl, CaCl₂, NH₄Cl, CaSO₄, and MgCl₂. Including soil pH as an independent variable in the regression to predict leaf Zn considerably improved R‐square values. The DTPA‐extractable soil Zn levels were very well correlated with Mehlich‐1‐extractable Zn. Mehlich‐3 extracted about 20% more soil Zn than Mehlich‐1, but Mehlich‐3 soil Zn was not as well correlated to Mehlich‐1 soil Zn as DTPA soil Zn. Lower pH solutions extracted more of the applied Zn, but more neutral solutions extracted Zn amounts which were better correlated with Zn uptake. On the other hand, Mehlich‐1, which had a lower pH, had better correlations with both applied Zn and leaf Zn than did Mehlich‐3. Shortening the DTPA extraction time to 30 minutes resulted in better correlations than the standard two hour extraction time. Chloride (Cl) was the best anion tested in relation to soil applied Zn recovery in combination with potassium (K), calcium (Ca), and aluminum (Al), and Cl optimized leaf Zn correlations for ammonium (NH₄), K, Ca, and magnesium (Mg). The larger the valence of the cation, the better the correlation with applied Zn and the poorer the correlation with leaf Zn.     

Reactive aluminum in the vermont soil test

Abstract

Determination of Reactive Al by extracting a soil sample with pH 4.8 NH₄ OAc (1.25 N acetate) characterizes for northern acid soils the quantity of soil acidity that must be neutralized to meet lime need and also lower the P adsorbing capacity. Extracted Al is used in conjunction with pH in 10 mM CaCl₂ to calculate the lime requirement directly. First, the amount of P fertilizer needed is approximated, based on the P intensity (Available P) determined in the same NH₄ OAc extract. Then the recommended amount is increased by a P‐fixation factor obtained from the Reactive Al measured, and decreased by a Reserve P factor derived from fluoride extractable P.

Unlike a buffer lime requirement method, which predicts lime needed to reach a target pH, the Reactive Al test estimates the quantity of acidity that must be neutralized to prevent fixation of P fertilizer by soil Al and to release P from Al‐bound sources. Attaining a particular target pH is not the primary goal. The Reserve P test measures the amount of unavailable Al phosphates that becomes partially available when lime needs are met.     

Applicability of 0.01 M CaCl2 as a single extraction solution for the assessment of the nutrient status of soils and other diagnostic purposes

Abstract

The applicability of 0.01 M CaCl₂ solution as a single extraction agent for soils as a basis for fertilizer recommendation was tested on a variety of soils both from the Netherlands and from some tropical countries. Air‐dry soil samples were subjected to extraction with 0.01 M CaCl₂ and to several conventional extraction procedures, and the results were compared. In the soil suspensions pH was measured, whereas in the extracts Na, K, Mg, P, different extractable N‐forms and Zn were measured. The values found in CaCl₂ extracts are discussed in relation to results of other extraction procedures and as to their potential value in soil quality assessment. It is concluded that a single extraction procedure with 0.01 M CaCl₂ can be applied for fertilizer recommendation purposes. The possibility of determining different extractable N‐forms (NH₄, NO₃, soluble organic N) significantly enhances the value of the method in predicting the N‐fertilizer needs. Furthermore it was found that the concentration of Zn in 0.01 M CaCl₂ extracts was a good indicator of phytotoxicity in a polluted area. Additional advantages of this extraction are low costs, simplicity and repro‐ducibility.     

Effect of B,Mn and Zn on nodulation and N2‐fixation in southernpeas

Abstract

Two greenhouse studies were conducted to evaluate the effect of B, Mn and Zn on nodulation and N₂‐fixation of southernpea (Vigna unguiculata (L.) Halp.) cultivars ‘Freezegreen’, ‘Mississippi Silver’ and ‘Pinkeye Purple Hull’. The cultivars were grown in plastic pots with a Norfolk sandy loam (fine, loamy siliceous thermic, Typic Paleudult) soil treated with B, Mn and Zn at rates of 0, 5, 10 and 20 kg/ha each at pH levels 5.5, 6.0 and 6.5. At pH 6.5 all micronutrient treatments significantly increased nodulation and N₂‐fixation over the control (no micronutrient applied). The effects of B, Mn and Zn on nodulation and N₂‐fixation depended on the cultivar and soil pH. For plants given the 5 kg/ha B and Mn treatments, ‘Mississippi Silver’ produced the highest number of nodules and ‘Pinkeye Purple Hull’ the least. At 20 kg/ha Zn, nodulation of ‘Freezegreen’ was highest and ‘Pinkeye Purple Hull’ the lowest. As a whole, maximum nodulation was at 5 kg/ha B and Mn and 20 kg/ha for Zn. Nitrogen fixation rates responded similarly except that the optimum rate for Zn was 10 kg/ha. Seed yield of plants peaked at 5 kg/ha for B and 10 kg/ha for Zn, indicating a possible relation of N₂‐fixation to seed yield.     

Sodium bicarbonate‐DTPA test for macro‐and micronutrient elements in soils

Abstract

Individual soil tests are used to assess plant nutrient element needs. Separate soil tests, however, are time consuming and costly. Our objective was to develop a 0.5M sodium bicarbonate (NaHCO₃) soil phosphorus (P) test in combination with 0.005M diethylenetriaminepentaacetic acid (DTPA) so macronutrient dements: ammonium‐nitrogen (NH₄‐N), nitrate‐nitrogen (NO₃‐N), P, potassium (K), calcium (Ca), and magnesium (Mg); and micronutrients: iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) could be quantified in one extraction. The NaHCO₃‐DTPA extracting solution is a combination of 0.5M NaHCO₃ and 0.005M DTPA and has a pH of 7.60±0.05. Sodium in the solution enhances the NH₄, K, Ca, and Mg extraction; bicarbonate (HCO₃) is for P extraction; DTPA chelates Ca, Mg, and micronutrients; and the water is for NO₃ extraction. Soil samples (0–15 cm depth) came from two sources. The first set was from 12 N x P dryland proso millet (Panicum miliaceum L.) experiments, conducted from 1985 through 1987 in eastern Colorado. These soils were extracted with potassium chloride (KCl), NaHCO₃, ammonium acetate (CH₃‐COONH₄), DTPA, ammonium bicarbonate DTPA (AB‐DTPA), and with the NaHCO₃‐DTPA solutions. The second set included 25 soils from Alabama, Georgia, North Carolina, and South Carolina and were analyzed only for available P with the NaHCO₃ and NaHCO₃‐DTPA methods. Simple linear correlations for macronutrient elements and micronutrients were highly significant. Critical levels for the macronutrient elements: NO₃‐N, P, and K were 27, 11, and 144 mg kg^‐1, respectively; and the critical levels for the micronutrients: Fe, Mn, Zn, and Cu were 3.9, 0.35, 0.97, and 0.24 mg kg^‐1, respectively.     

Influence of Gyttja on Shoot Growth and Shoot Concentrations of Zinc and Boron of Wheat Cultivars Grown on Zinc‐Deficient and Boron‐Toxic Soil

Abstract

Greenhouse experiments were carried out to study the influence of gyttja, a sedimentary peat, on the shoot dry weight and shoot concentrations of zinc (Zn) and boron (B) in one bread wheat (Triticum aestivum L., cv. Bezostaja) and one durum wheat (Triticum durum L., cv. Kiziltan) cultivar. Plants were grown in a Zn‐deficient (DTPA‐Zn: 0.09 mg kg^?1 soil) and B‐toxic soil (CaCl₂/mannitol‐extractable B: 10.5 mg kg^?1 soil) with (+Zn = 5 mg Zn kg^?1 soil) and without (?Zn = 0) Zn supply for 55 days. Gyttja containing 545 g kg^?1 organic matter was applied to the soil at the rates of 0, 1, 2.5, 5, and 10% (w/w). When Zn and gyttja were not added, plants showed leaf symptoms of Zn deficiency and B toxicity, and had a reduced growth. With increased rates of gyttja application, shoot growth of both cultivars was significantly enhanced under Zn deficiency, but not at sufficient supply of Zn. The adverse effects of Zn deficiency and B toxicity on shoot dry matter production became very minimal at the highest rate of gyttja application. Increases in gyttja application significantly enhanced shoot concentrations of Zn in plants grown without addition of inorganic Zn. In Zn‐sufficient plants, the gyttja application up to 5% (w/w) did not affect Zn concentration in shoots, but at the highest rate of gyttja application there was a clear decrease in shoot Zn concentration. Irrespective of Zn supply, the gyttja application strongly decreased shoot concentration of B in plants, particularly in durum wheat. For example, in Zn‐deficient Kiziltan shoot concentration of B was reduced from 385 mg kg^?1 to 214 mg kg^?1 with an increased gyttja application. The results obtained indicate that gyttja is a useful organic material improving Zn nutrition of plants in Zn‐deficient soils and alleviating adverse effects of B toxicity on plant growth. The beneficial effects of gyttja on plant growth in the Zn‐deficient and B‐toxic soil were discussed in terms of increases in plant available concentration of Zn in soil and reduction of B uptake due to formation of tightly bound complexes of B with gyttja.