Cellulose Acetate Microbeads for Controlled Delivery of Essential Micronutrients

The controlled delivery of micronutrients to soil and plants is essential to increase agricultural yields. However, this is today achieved using fossil fuel-derived plastic carriers, posing environmental risks and contributing to global carbon emissions. In this work, a novel and efficient way to prepare biodegradable zinc-impregnated cellulose acetate beads for use as controlled release fertilizers is presented. Cellulose acetate solutions in DMSO were dropped into aqueous antisolvent solutions of different zinc salts. The droplets underwent phase inversion, forming solid cellulose acetate beads containing zinc, as a function of zinc salt type and concentration. Even higher values of zinc uptake (up to 15.5%) were obtained when zinc acetate was added to the cellulose acetate-DMSO solution, prior to dropping in aqueous zinc salt antisolvent solutions. The release profile in water of the beads prepared using the different solvents was linked to the properties of the counter-ions via the Hofmeister series. Studies in soil showed the potential for longer release times, up to 130 days for zinc sulfate beads. These results, together with the efficient bead production method, demonstrate the potential of zinc-impregnated cellulose acetate beads to replace the plastic-based controlled delivery products used today, contributing to the reduction of carbon emissions and potential environmental impacts due to the uptake of plastic in plants and animals.</p

Cellulose Acetate Microbeads for Controlled Delivery of Essential Micronutrients

The controlled delivery of micronutrients to soil and plants is essential to increase agricultural yields. However, this is today achieved using fossil fuel-derived plastic carriers, posing environmental risks and contributing to global carbon emissions. In this work, a novel and efficient way to prepare biodegradable zinc-impregnated cellulose acetate beads for use as controlled release fertilizers is presented. Cellulose acetate solutions in DMSO were dropped into aqueous antisolvent solutions of different zinc salts. The droplets underwent phase inversion, forming solid cellulose acetate beads containing zinc, as a function of zinc salt type and concentration. Even higher values of zinc uptake (up to 15.5%) were obtained when zinc acetate was added to the cellulose acetate–DMSO solution, prior to dropping in aqueous zinc salt antisolvent solutions. The release profile in water of the beads prepared using the different solvents was linked to the properties of the counter-ions via the Hofmeister series. Studies in soil showed the potential for longer release times, up to 130 days for zinc sulfate beads. These results, together with the efficient bead production method, demonstrate the potential of zinc-impregnated cellulose acetate beads to replace the plastic-based controlled delivery products used today, contributing to the reduction of carbon emissions and potential environmental impacts due to the uptake of plastic in plants and animals

Efficiency of soluble and insoluble sources of manganese for soybean nutrition in the Brazilian Cerrado

O objetivo deste trabalho foi avaliar a eficiência de fontes e doses de magnésio solúvel (MnSO4.H2O) e insolúvel (MnCO3) nos processos de absorção, transporte e redistribuição deste nutriente na soja (Glycine max), bem como na produtividade da cultura, em solo de Cerrado. O delineamento experimental foi em blocos ao acaso, em arranjo fatorial 4×2 – quatro doses (150, 250, 350 e 450 g ha-1) × duas fontes (MnSO4.H2O e MnCO3) de Mn –, com quatro repetições. Nas safras de 2015/2016 e 2016/2017, realizaram-se adubações foliares no terceiro trifólio e avaliaram-se os conteúdos de Mn e a produtividade da soja. Em ambas as safras, a fertilização foliar com Mn aumentou os teores do nutriente nas folhas, nos caules e nos grãos, mas não afetou o rendimento de grãos e a produção de matéria seca. Os teores máximos de Mn nas folhas foram obtidos com doses entre 150 e 450 g ha-1. A aplicação de MnSO4.H2O aumentou a absorção, o transporte e a redistribuição de Mn na planta, com desempenho superior ao de MnCO3. A fertilização foliar com MnSO4.H2O em soja, em solo de Cerrado, aumenta os teores de Mn nas folhas, mas não a produtividade e a produção de matéria seca.The objective of this work was to evaluate the efficiency of sources and rates of soluble (MnSO4.H2O) and insoluble (MnCO3) manganese on the processes of uptake, transport, and redistribution of this nutrient in soybean, as well as on crop yield, in Cerrado soil. The experimental design was randomized complete blocks in a 4×2 factorial arrangement – four rates (150, 250, 350, and 450 g ha-1) × two sources (MnSO4.H2O and MnCO3) of Mn –, with four replicates. In the 2015/2016 and 2016/2017 crop seasons, foliar fertilizations were carried out on the third trifoliate leaflet, and Mn content and soybean yield were evaluated. In both crop seasons, Mn foliar fertilization increased the contents of the nutrient in leaves, stems, and grains, but did not affect grain yield and dry matter production. The maximum Mn contents in leaves were obtained with rates between 150 and 450 g ha-1. The fertilization with MnSO4.H2O increased Mn uptake, transport, and redistribution in the plant, with a performance superior to that of MnCO3. Foliar fertilization with MnSO4.H2O in soybean, in a Cerrado soil, increases Mn contents in the leaves but not yield and dry matter production

Soil-app: a tool for soil analysis interpretation

New apps have changed the traditional way of learning and teaching; they are also applied as a quickly executed and effective method in agriculture. Soil-app is a web application with a friendly click-point interface built through packages lodged in R software. The app is an advanced model of an open-source platform to support teaching and learning activities in soil analyses and fertilizer recommendations. Soil-app includes soil test interpretation, soil amendment calculations (lime and gypsum), the fertilizer rate for the most important crops in Brazil, an NPK blend calculator, and NPK blend evaluation. It also includes experimental statistical analysis as applied to soil science. Soil-app is a user-friendly and high-performance tool, garnering fast adoption by both students and professionals. It is available for network use through the following link: http://www.genetica.esalq.usp.br/alogamas/R.htm

Caracterização da absorção foliar de fontes de zinco pela cultura da soja (Glycine max L.)

Zinc (Zn) is an essential element for plant, animal and human nutrition. Around the world, ca. 800,000 children under 5 years die annually due to a Zn-deficient diet. The application of zinc in crops can be performed on plant leaves or in the soil, however, the low use-efficiency is remarkable. This study aims to understand and characterize the absorption, transport and metabolization of Zn when applied on soybean leaves by the most common fertilizers used by worldwide, i.e. inorganic salts, complexes/chelates, and concentrated suspensions, as well as evaluate possibility of the employment of new technologies, such as nanoparticles and cellulose microspheres. X-ray fluorescence (XRF) and X-ray absorption (XANES) spectroscopy were employed to perform in vivo analysis on soybean plants together with greenhouse trials. The absorption and transport of Zn depended on the type of Zn source. Zinc from ZnSO4 was absorbed and transported faster than ZnO commercial suspension, while Zn applied as Zn-phosphite was transported faster than Zn-EDTA. The XANES analysis demonstrated that Zn from ZnSO4 and Zn phosphite was transported bound with organic acids such as malate and citrate. Conversely, Zn supplied by Zn-EDTA was transported in its pristine form. In a short-term experiment, i.e. few days, cellulose microspheres were able to reduce the toxicity caused by ZnSO4 salts and increase Zn transport trough leaf petiole. However, under longer evaluation, i.e. a couple of weeks, the root application of ZnSO4 increased by 42% the Zn accumulation in soybean plants compared to the control (low Zn supply). Additionally, root uptake mechanism under hydroponics was more efficient than the foliar application of ZnSO4, ZnO nanoparticles and ZnSO4 + cellulose microspheres. The foliar and root application of Zn did not affect the activity of ezymes related to the metabolism of reactive oxygen species. Understanding the mechanisms ruling the foliar absorption and metabolization of nutrients is fundamental for the development of the next generation of fertilizers. Therefore, more studies on this subject are necessaryO zinco (Zn) é um elemento essencial para a nutrição vegetal, animal e humana. Em todo o mundo, aproximadamente 800.000 crianças menores de 5 anos morrem anualmente devido a deficiência de Zn em suas dietas. A aplicação de Zn nas lavouras pode ser realizada nas folhas ou no solo, porém, é notável a baixa eficiência de sua utilização. Este estudo buscou caracterizar e entender a absorção, transporte e metabolização de Zn quando aplicado em folhas de soja pelas fontes de fertilizantes mais utilizadas mundialmente, i.e. sais inorgânicos, complexos/quelatos e suspensões concentradas, bem como avaliar a possibilidade de utilização de novas tecnologias, tais como nanopartículas e microesferas de celulose. As espectrometrias de fluorescência (XRF) e absorção de raios X (XANES) foram empregadas na realização de análises in vivo, juntamente com ensaios em casa de vegetação. A absorção e transporte de Zn foram dependentes da fonte aplicada. O Zn aplicado como ZnSO4 foi mais rapidamente absorvido e transportado do que aquele provindo de suspensão concentrada comercial, ao passo que o Zn aplicado como fosfito de Zn foi transportado mais rápido quando comparado ao Zn-EDTA. A ferramenta XANES demonstrou que o Zn aplicado como ZnSO4 e fosfito de Zn foi transportado ligado a ácidos orgânicos, como malato e citrato, por outro lado, o Zn advindo do Zn-EDTA permaneceu em sua forma primitiva. Em um curto período, i.e. alguns dias, as microesferas de celulose foram capazes de reduzir a toxicidade causada pelo ZnSO4 e aumentar o transporte de Zn no pecíolo das folhas. Contudo, em avaliações mais longas, i.e. na escala de semanas, a aplicação de ZnSO4 na raiz aumentou em 42% o acúmulo de Zn nas plantas de soja em relação ao controle (baixo suprimento de Zn). A capacidade de transferência de Zn pela via radicular, em solução nutritiva, também foi maior do que aquela oferecida pela aplicação foliar de ZnSO4, nanopartículas de ZnO e ZnSO4 + microesferas de celulose. A aplicação foliar e radicular de Zn não afetou o a atividade das enzimas do sistema antioxidante. Compreender os mecanismos que regem a absorção foliar e a metabolização de nutrientes é fundamental para o desenvolvimento da próxima geração de fertilizantes, portanto mais estudos nesta temática são necessário

Physicochemical characterization of fertilizers containing concentrated suspensions of CuO, MnCO3 and ZnO

The utilization of insoluble sources of micronutrients as concentrated suspensions (CSs) is increasing in Brazilian agriculture; however, much information regarding the physicochemical characterization of these products is required to demonstrate the absorption behavior by plant leaves. This study aimed to characterize the CSs available on the Brazilian market to support their potential use as foliar fertilizers. We selected five CSs containing Mn, five CSs containing Zn and three CSs containing Cu from five different companies. In each product, the mean particle size was evaluated by dynamic light scattering (DLS), the particle shape and size were evaluated by scanning electron microscopy (SEM), the aggregation degree was determined by the zeta potential and the heavy metal contents were determined by acid digestion followed by reading on ICP-OES. The mean hydrodynamic diameter of fertilizers containing Cu, Mn and Zn was 315 ± 55, 378 ± 184 and 435 ± 107 nm, respectively. The zeta potential varied from –20 to –30 mV, indicating potential particle aggregation and formation of higher structures. SEM images indicated great variation in the size and shape of the particles in each product. All products exhibited concentrations of toxic elements within the legislation thresholds. The average particle size of CSs currently marketable in Brazil does not allow their classification as nanomaterials (&lt; 100 nm). Therefore, their foliar absorption is unlikely, once the particle size is higher than the exclusion limit observed for stomata and cuticle pathways, as well as the nutrient content as ions is low according to the solubility constant

Cellulose Microbeads:Toward the Controlled Release of Nutrients to Plants

The use of conventional fertilizers is associated with pollution due to leaching and a mismatch between release rates and crop requirements for optimal development. Slow-release fertilizers could address both problems. Here, the synthesis and properties of a zinc fertilizer composed of cellulose microbeads loaded with aqueous ZnSO4 are reported for the first time. UV-vis spectrophotometry showed that the beads immersed in water released all Zn2+ in about 30 min, regardless of the initial Zn2+ concentration. In two sandy substrates (a pure sand and a sandy loam substrate), microprobe X-ray fluorescence spectroscopy determined Zn2+ release from beads to the substrate corresponding to count rates of about 0.115 mm min-1 s-1, irrespective of the substrate and with a low sensitivity for the water content, except in a very dry range. These results indicate that these microbeads could represent a practical and sustainable solution for efficient nutrient supply in agriculture. </p

Cellulose Microbeads:Toward the Controlled Release of Nutrients to Plants

The use of conventional fertilizers is associated with pollution due to leaching and a mismatch between release rates and crop requirements for optimal development. Slow-release fertilizers could address both problems. Here, the synthesis and properties of a zinc fertilizer composed of cellulose microbeads loaded with aqueous ZnSO4 are reported for the first time. UV-vis spectrophotometry showed that the beads immersed in water released all Zn2+ in about 30 min, regardless of the initial Zn2+ concentration. In two sandy substrates (a pure sand and a sandy loam substrate), microprobe X-ray fluorescence spectroscopy determined Zn2+ release from beads to the substrate corresponding to count rates of about 0.115 mm min-1 s-1, irrespective of the substrate and with a low sensitivity for the water content, except in a very dry range. These results indicate that these microbeads could represent a practical and sustainable solution for efficient nutrient supply in agriculture. </p