Initial Zn Research Articles

Determination of critical level of zinc in non-calcareous soils for predicting response of wheat to applied zinc

Studies were conducted in ten non-calcareous arid brown soils (India) to determine the critical level of soil Zn for predicting response of wheat to zinc fertilization. The per cent mean response at 5 mg kg−1 added Zn varied from 1.3 to 51.4 with a mean value of 17.5 per cent over control in terms of grain yield (g pot−1). Further, Zn application resulted in significant increase in Zn concentration in various plant parts in all the soils irrespective of the initial Zn status. The critical level of Zn in soil and plant below which response to applied Zn may be expected was found to be 1.75 mg kg−1 for 0.1 N HC1 extractable soil Zn and 1.7 mg kg−1 for plant tissue Zn.

Determination of critical limit of zinc in rice soils in India for predicting response of rice to zinc application

Abstract Studies were conducted in ten non-calcareous alluvial soils (India) to determine the critical level of soil Zn for predicting response of rice ( Oryza sativa L.) to zinc application. The critical limit of Zn in rice soils below which plant response to Zn fertilization may be expected was found to be 2.1 ppm HCl-extractable Zn. In soils with values below this level, the plants showed typical symptoms of Zn deficiency and the percent mean grain, straw, husk and total dry matter yield (g per pot), respectively. The rice husk had the highest concentration of Zn whereas the grain had the lowest. Zinc application significantly increased Zn concentrations in various plant parts in all the soils irrespective of the initial Zn status. In general, Zn responses were observed when plant Zn concentration was less than 24 ppm on a dry weight basis. The HCl-extractable soil Zn was positively correlated with the percentage yields of grain ( r = 0.69 ∗ ) and straw ( r = 0.56).

Specific zinc sorption by some gleysolic C horizons in Quebec soils, Canada

Abstract Specific sarption of low quantities of Zn in eight gleysolic C horizons in Quebec soils was studied in dilute Cacl2 solutions. Initial Zn concentrations were between 5 and 30 ppm. The range of specific Zn sorbed calculated as percentages of Zn added ware very high to moderately high indicating a high affinity sarption for Zn of the sorbed complex surface. Specific Zn sarption was found to agree with the Freundlich and Langmuir isotherms over a large range of concentrations. Amounts of specific Zn sorbed were very highly correlated with the pH of the equilibrium solutions. Clay content and soil pH were the dominant soil properties influencing the specific Zn sorption. Nevertheless, soil pH was the only variable which had contributed the most to the variation of maximum specific Zn sorption. Also, the ratio of clay content to CEC was significantly correlated with specific Zn sorption parameters and was attributed to the interaction of soil clay content with CEC. The values of Zn solubility calculat...

Changes in histochemically detectable calcium and zinc during tolbutamide-induced degranulation and subsequent regranulation of rat pancreatic islets.

Secretory granules of pancreatic B-cells contain high concentrations of zinc and calcium. The effect of gradual degranulation (induced by tolbutamide over a period of 3 days) and the subsequent regranulation (over a period of 4 days) on the histochemically detectable zinc (Zn) and calcium (Ca) content of B-cells was investigated. Zn was stained by dithizone, Ca by glyoxal-bis-(2-hydroxyanil), (GBHA), and B-granules by aldehyde fuchsin (AF). The staining intensities were determined cytophotometrically. A decrease of the granulation by 50% causes a comparable decrease of the Zn content. Almost complete degranulations, however, hardly further diminished the Zn content. Regranulation restores the Zn content parallel to the granulation. The presence of 40% of the initial Zn content in degranulated B-cells suggests the existence of a non-granular Zn fraction. The Zn content of B-cells may be partly involved in the storage of insulin as a Zn-insulin complex in the secretory vesicles. A-cells, however, contain even more (+ 30%) Zn than B-cells. Degranulation of B-cells is accompanied by a moderate decrease of the zinc content of the A-cells. The function of Zn in A-cells is completely unknown. Degranulation of B-cells causes the GBHA-Ca content to decrease to a very low level parallel to the AF-positive granulation. During regranulation the GBHA-Ca content restores parallel to the granulation and reaches after complete regranulation a slightly higher level than in untreated control rats. Almost complete disappearance of CBHA-Ca in the B-cells is accompanied by a decrease of the total islet calcium content of 33%. The results indicate that GBHA stains a Ca fraction which is mainly localized to the secretory granules. The stainability of granular Ca by GBHA is probably based on: a) the high Ca concentration in the granules, b) the presence of ionized Ca in the granules, due to the low intragranular pH, and c) on the properties of GBHA, which stains, under conditions used, only ionized (possibly also readily ionizable) Ca.

Influence of Solution Composition on Sorption of Zinc by Soils

AbstractThe effect of soil solution composition on Zn sorption was investigated in nine soils of varying physical and chemical properties. Most of Zn applied in 0.01 N CaCl2 solution was strongly sorbed by the soils and desorption by 0.01 N CaCl2 solution was negligible even after five desorption cycles. At initial Zn solution concentrations of ⩽ 10 ppm, sorption could be described by the Freundlich sorption isotherm equation. Deviations from this equation were observed at higher concentrations, suggesting the presence of more than one type of site or mechanism for Zn sorption in the soils.The effects of anion species (Cl‐, NO‐3, and SO2‐4) and ionic strength on Zn sorption were examined at anion concentrations of 0.005, 0.02, and 0.1M. Complexation of Zn (as ZnSO04) in the SO2‐4 system was higher than in either the NO‐3 [Zn(NO3)+] or Cl‐ [Zn(Cl)+] system. However, under the experimental conditions examined, neither ionic strength nor anion complex formation significantly affected Zn sorption.The presence of EDTA (Ethylenediaminetetraacetic acid) in the soil suspension significantly decreased Zn sorption by the three soils investigated. Only a slight difference in Zn sorption was observed whether EDTA was added to the (Zn containing) soil solution before or after contact with soil.The influence of Ni and Cu on Zn sorption was significant only when metal concentration in the soil solution was in excess of the sorbing capacity of the soil. In this case, Cu was more effective than Ni in decreasing Zn sorption.

Effects of Pyrophosphate, EDTA, and DTPA on Zinc Sorption by Montmorillonite

AbstractThe effects of pyrophosphate (PP), pH, ionic strength, EDTA, and DTPA on zinc (Zn) sorption by montmorillonite were studied in order to evaluate the role of pyrophosphate in Zn solubilization. In such a system PP dissolution of organic matter and its subsequent complexation of Zn was limited and would not affect the interpretation of the results. The effectiveness of PP in complexing Zn was dependent on the levels of Ca, initial PP concentration, and pH of the montmorillonite suspension. Decreased sorption of PP with increasing pH, as well as markedly greater sorption of PP by Ca‐montmorillonite than by K‐montmorillonite, suggests the existence of a sorption process which could include surface adsorption and precipitation.At initial PP concentrations of 1.92 mM, Zn solubilization decreases monotonically with increasing pH, while at 9.6 mM initial PP, a minimum in Zn solubilization is observed at about pH 6.0. This trend of solubilization could be attributed to decreased Zn sorption and increased Zn complexing with PP. At pH greater than about 7.5, PP is comparable to EDTA and DTPA in Zn solubilization, but only at PP molar concentrations some 40 times greater than the organic ligands. Equilibration time (2 to 192 hours) had little effect on PP concentration or on Zn concentration. Regardless of which of the ligands was used, the sorption of Zn reached completion in most cases within 2 hours. For EDTA and DTPA, provided that their concentration was greater than Zn concentration, sorption of Zn was found to be a relatively slow process. Approximately 40% (EDTA) and 20% (DTPA) of the initial Zn was sorbed after 192 hours.

Diffusion of Zinc in Soils: III. Relation to Zinc Adsorption Isotherms

AbstractThe rate of cation diffusion in soil is influenced by the buffering effect of the adsorbed cation on the solution concentration, dCl/dC, i.e., the change in solution zinc concentration with respect to change in the total diffusible soil zinc concentration. This effect was studied with Zn using four silt loam soils having a wide range of initial exchangeable Zn contents and cation exchange capacities (CEC). Zinc adsorption isotherms for these soils had slopes that increased as CEC decreased. The effective zinc diffusion coefficient, De, was measured at five Zn levels on each soil. Measured De, correlated with dCl/dC (r2 = 0.86). Values of De calculated from known values for volumetric moisture content, tortuosity, and dCl/dC were larger than observed De by factors of 5.5 to 18.2. Inclusion of CEC in a multiple regression of observed De with calculated De significantly increased r2 from 0.87 to 0.90. An additional soil factor related to CEC needs to be included to accurately calculate De values for Zn.

Efficacy of major nutrients in rice production

Nutrients efficacy means increased rice yield upon soil fertilization. Purposefully a particular nutrient stress was created in soil through missing element technique from complete treatment (NPKSZn) and its reserve management (addition of omitted nutrient) effect in increasing yield was considered as a measuring stick of nutrients efficacy. The omission of all NPKSZn fertilizers from complete treatment (NPKSZn) drastically decreased yield than continuously fertilized complete treatment. Similar extent of' yield increase was observed when all NPKSZn fertilizer was applied in absolute control plot indicating that every soil needs complete addition of NPKSZn fertilizers irrespective of seasons whether the plot was continuously fertilized or not. The amount of yield increase obtained upon a missing element fertilization nearly equivalent amount of yield loss as aloofness of that particular nutrient as compared to complete fertilization. It means lhc efficacy of each essential nutrient might increase yield in a similar manner depending on their magnitude of deficiency level in the soil. Continuous application of N @ 120 kg/ha in boro and 80 kg/ha in T.aman with PKSZn @ 25-33-20-05 kg/ha per season improve total soil N, S and Zn. But exchangeable K decreased compared to initial soil status. In case of P fertilization, this rate maintained the initial soil P level. However, available Zn was found well above critical level even after 45th crop as because of high initial soil available Zn level. Key Words: Nutrient efficacy, rice yield, soil fertilization. doi: 10.3329/bjar.v33i4.2308 Bangladesh J. Agril. Res. 33(4) : 639-645, December 2008