Manganese and zinc in acidic agricultural soils from Central Spain: Distribution and phytoavailability prediction with chemical extraction tests

The extractability and distribution of manganese (Mn) and zinc (Zn) were evaluated in acidic agricultural soils from Central Spain. Both single (0.1 M hydrochloride [HCl] and 0.05 M ethylenediaminetetraacetate [EDTA]) and sequential extraction procedures (SEP) (modified Tessier procedure and Community Bureau of Reference [BCR] protocol) were applied to 29 representative soils that belong to the Alfisol, Inceptisol, and Entisol orders. Average relative Mn extractabilities with respect to the total content (16.6% for HCl and 31.9% for EDTA) were higher than those of Zn (7.7% for HCl and 6.5% for EDTA). Manganese was mainly released in the oxide-bound phase of both SEP (33.1% for modified Tessier and 48.9% for BCR), whereas Zn was predominantly found in the residual fraction (49.1% for modified Tessier and 31.4% for BCR). Significant correlations were only found between the amounts of extractable Zn and the oxide-bound fraction in both SEP. Few relationships were established between Zn fractions extracted by the BCR procedure and those obtained with the Tessier method. Both metal concentrations in spring barley (Hordeum vulgare L., cv Beka) grown in 11 selected soils and the calculated soil/plant transfer coefficients (soil/plant concentration factor (CF), mean values of 31.2 for Mn and 196 for Zn) were poorly (or not at all) correlated with the different extracted soil fractions (single and sequential). A number of empirical equations have been obtained by regression analyses to predict the Mn and Zn uptake by barley, with soil metal forms and some soil characteristics as components (pH for Mn and organic matter for Zn). Values of R2 in the equations were relatively low (<68%). Single-extraction techniques produced worse results than SEP for the evaluation of Mn phytoavailability. The modified Tessier procedure provided better predictions of Zn uptake by plants than BCR, but not better than those obtained with the HCl extraction method

Efecto de la adición de una turba comercial en la asimilabilidad del cobre, zinc, hierro y manganeso de un suelo en el que se ha cultivado trigo

Se ha estudiado el efecto de la adición de diferentes cantidades de una turba comercial (con un 80 % de turba rubia y un 20% de turba negra) en la asimilabilidad de los elementos nutritivos en un suelo calcáreo en el que se cultivó trigo. Para ello se determinaron los contenidos en N, P y K, así como las concentraciones totales y potencialmente asimilables para las plantas de los micronutrientes Cu, Zn, Fe y Mn. También se determinó el rendimiento en grano y el índice de cosecha del cultivo de trigo realizado en función del tratamiento de turba aplicado. Los resultados estadísticos no mostraron diferencias significativas entre tratamientos en cuanto a la concentración total de N, K, Cu, Zn, Fe y Mn en el suelo de la rizosfera del cultivo. Sin embargo sí se obtuvieron diferencias significativas (P < 0,05) en las concentraciones de Cu, Zn, Fe y Mn potencialmente disponibles en el suelo, aumentando en general, dichas concentraciones con los incrementos de la dosis de turba. El aumento de la dosis de turba también afectó al valor de pH del suelo, disminuyendo el valor del mismo a medida que aumenta dicha dosis. El mayor rendimiento en grano del cultivo de trigo se obtuvo con el tratamiento con turba que consiguió en el suelo un contenido en materia orgánica del 2,5 %

Residual zinc forms in weakly acidic and calcareous soil after and oilseed flax crop

The different chemical forms of Zn found in soils exhibit different levels of reactivity, solubility and availability to plants. Sequential extraction procedures (SEP) are applied in soils to partition metal into operationally-defined geochemical fractions. The bioavailability of metals in soils is related to these chemical fractions and not to total metal content. Furthermore, single extraction methods, such as DTPA or Mehlich-3, are commonly used to predict Zn availability to plants. Other, more recently developed, method that try to simulate the conditions of the soil rhizosphere use a mixture of low-molecular-weight organic acids (LMWOAs) as extractants. According to various researchers, the BaCl2 reagent only extracts elements which are physically adsorbed on particles and it can be used to estimate the easily leachable Zn portion. Flax (Linum usitatisimum L.) is a major oilseed meadow crop grown throughout the world and is more sensitive to Zn deficiency than cereal crops such is wheat. The objectives of this study were to determine soil chemical Zn pools, potential Zn availability and easily leachable Zn in two residual soils after a flax harvest

Fate and effects of uncoated ZnO nanoparticles on nine crops exposed in two agricultural soils, a calcareous and an acidic soil.

The nanotechnology has a wide range of applications including those that deliberately release nanoparticles (NPs) into the environment. The use of nanoformulations containing agrochemicals to soils provides an efficient way to apply pesticides and fertilizers in a controlled mode. The zinc oxide nanoparticles (ZnO NPs) are of particular interest due to their increasing incorporation into agricultural products

Toxicity of ZnO nanoparticles, ZnO bulk and ZnCl2 on earthworms in a spiked natural soil and toxicological effects of leachates on aquatic organisms

The present study assessed the uptake and toxicity of ZnO nanoparticles (NPs), ZnO bulk, and ZnCl2 salt in earthworms in spiked agricultural soils. In addition, the toxicity of aqueous extracts to Daphnia magna and Chlorella vulgaris was analyzed to determine the risk of these soils to the aquatic compartment. We then investigated the distribution of Zn in soil fractions to interpret the nature of toxicity. Neither mortality nor differences in earthworm body weight were observed compared with the control. The most sensitive end point was reproduction. ZnCl2 was notably toxic in eliminating the production of cocoons. The effects induced by ZnO-NPs and bulk ZnO on fecundity were similar and lower than those of the salt. In contrast to ZnO bulk, ZnO-NPs adversely affected fertility. The internal concentrations of Zn in earthworms in the NP group were greater than those in the salt and bulk groups, although bioconcentration factors were consistently <1. No relationship was found between toxicity and internal Zn amounts in earthworms. The results from the sequential extraction of soil showed that ZnCl2 displayed the highest availability compared with both ZnO. Zn distribution was consistent with the greatest toxicity showed by the salt but not with Zn body concentrations. The soil extracts from both ZnO-NPs and bulk ZnO did not show effects on aquatic organisms (Daphnia and algae) after short-term exposure. However, ZnCl2 extracts (total and 0.45-μm filtered) were toxic to Daphnia

Soil pH effects on the Toxicity of zinc oxide nanoparticles to soil bacterial communities.

The environmental levels of ZnO nanoparticles (nZnO) are increasing continually given the widespread and expanding applications of this material. Soil pH appears to be one of the key factors affecting the behavior and toxicity of metal nanoparticles in soi

Biofortificación de cereales con micronutrientes

La malnutrición en humanos por falta de micronutrientes afecta a más de 3.000 millones de personas en todo el mundo. Las deficiencias más frecuentes son de zinc (Zn), hierro (Fe), vitamina A y yodo (I) y son particularmente evidentes en las mujeres y los niños de países en desarrollo. Las carencias de Zn y Fe afectan a alrededor de un tercio de la población del mundo y se están extendiendo en los países desarrollados, especialmente en Europa. La biofortificación agronómica, incrementando la concentración de micronutriente Zn en la planta, es un medio para evitar la deficiencia de Zn en animales y humanos y consiste en aumentar el contenido de micronutrientes en las plantas mediante la fertilización de los cultivos

Influence of soil pH in the effects of ZnONPs on the antioxidant activities and Zn uptake in three plant species (T aestivum, R. sativus and Z. mays)

In recent years, the study of phytotoxicity of NPs has made rapid progress, but important issues remain to be solved, among them, the role of soil and the importance of the physicochemical soil characteristics for their toxicity and accumulation potential

Fate and effects of uncoated ZnO nanoparticles on nine crops exposed in two agricultural soils, a calcareous and an acidic soil.

The nanotechnology has a wide range of applications including those that deliberately release nanoparticles (NPs) into the environment. The use of nanoformulations containing agrochemicals to soils provides an efficient way to apply pesticides and fertilizers in a controlled mode. The zinc oxide nanoparticles (ZnO NPs) are of particular interest due to their increasing incorporation into agricultural products

Soil chemical extraction tests to estimate zinc plant availability from engineered ZnO nanoparticles applied to agricultural soils.

The Zn oxide nanoparticles (ZnO NPs) have been proposed as a possible Zn fertilizer to alleviate Zn deficiency in soils [1]. The NPs in the soil are subjected to chemical and biological reactions and physical processes, and they can be either retained in the solid matrix or mobilized into pore water, which have a profound impact on their availabilit