253 research outputs found
Assessing the Effect of Organoclays and Biochar on the Fate of Abscisic Acid in Soil
10 pĂĄginas.-- 6 figuras.-- 2 tablas.-- 56 referencias.-- The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.jafc.6b03668The potential use of allelopathic and signaling compounds as environmentally friendly agrochemicals is a subject of increasing interest, but the fate of these compounds once they reach the soil environment is poorly understood. This work studied how the sorption, persistence, and leaching of the two enantiomers of the phytohormone abscisic acid (ABA) in agricultural soil was affected by the amendments of two organoclays (SA-HDTMA and Cloi10) and a biochar derived from apple wood (BC). In conventional 24-h batch sorption experiments, higher affinity toward ABA enantiomers was displayed by SA-HDTMA followed by Cloi10 and then BC. Desorption could be ascertained only in BC, where ABA enantiomers presented difficulties to be desorbed. Dissipation of ABA in the soil was enantioselective with S-ABA being degraded more quickly than R-ABA, and followed the order unamended > Cloi10-amended > BC-amended > SA-HDTMA-amended soil for both enantiomers. Sorption determined during the incubation experiment indicated some loss of sorption capacity with time in organoclay-amended soil and increasing sorption in BC-amended soil, suggesting surface sorption mechanisms for organoclays and slow (potentially pore filling) kinetics in BC-amended soil. The leaching of ABA enantiomers was delayed after amendment of soil to an extent that depended on the amendment sorption capacity, and it was almost completely suppressed by addition of BC due to its irreversible sorption. Organoclays and BC affected differently the final behavior and enantioselectivity of ABA in soil as a consequence of dissimilar sorption capacities and alterations in sorption with time, which will affect the plant and microbial availability of endogenous and exogenous ABA in the rhizosphere.This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Project AGL2014- 51897-R), EU FACCE-JPI (Designchar4food Project), and Junta de Andalucıa (P011-AGR-7400 and Research Group Ì AGR-264), cofinanced with European FEDER funds. The use of trade, firm, or corporation names in this paper is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture, the Agricultural Research Service, or the Instituto de Recursos Naturales y Agrobiologıa de Sevilla Ì (IRNAS-CSIC) of any product or service to the exclusion of others that may be suitablePeer reviewe
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Spring 1983 Conference Issue
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Manganese-coated IRIS to document reducing soil conditions
Iron-coated indicatorof reduction in soils (IRIS) devices have been used for nearly two decades to help assess and document reducing conditions in soils, and official guidance has been approved for interpreting these data. Interest in manganese (Mn)-coated IRIS devices has increased because Mn oxides are reduced under more moderately reducing conditions than iron (Fe) oxides (which require strongly reducing conditions), such that they are expected to be better proxies for some important ecosystem services like denitrification. However, only recently has the necessary technology become available to produce Mn-coated IRIS, and the need is now emerging for guidance in interpreting data derived from Mn IRIS. Ninety-six data sets collected over a 2-yr period from 40 plots at 18 study sites among eight states were used to compare the performance of Mn-coated IRIS with Fe-coated IRIS and to assess the effect of duration of saturation and soil temperature as environmental drivers on the reduction and removal of the oxide coating. It appears that the current threshold prescribed by the National Technical Committee for Hydric Soils for Fe-coated IRIS is appropriate for periods when soil temperatures are warmer (\u3e11 °C), but is unnecessarily conservative when soil temperatures are cooler (5â11 °C). In contrast, Mn-coated devices are particularly useful early in the growing season when soil temperatures are cool. Our data show that when using a threshold of 30% removal of Mn oxide coatings there is essentially 100% confidence of the presence of reducing soil conditions under cool (\u3c11 °C) conditions
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Spring 1984 Conference Issue
Research Update (page 3) Low Management Kentucky Bluegrass Cultivar Trials (5) Nitrogen Leaching Losses from N Fertilizer Applied to Turf (8) Fifty-third Annual Turf Conference and Eighth Industrial Show (10) Liquid Versus Dry Nitrogren Fertilizer Applications on Kentucky Bluegrass (13) Growth Retardant, Embark (16) Fungicides: The Good, The Bad and The Ugly (18
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Biochar research activities and their relation to development and environmental quality. A meta-analysis
Biochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and poverty. However, impact of biochar research on scientists, politicians and end-users in poor tropical countries remains unknown; assessing needs and interests on biochar is essential to develop reliable knowledge transfer/translation mechanisms. The aim of this publication is to present results of a meta-analysis conducted to (1) survey global biochar research published between 2010 and 2014 to assess its relation to human development and environmental quality, and (2) deduce, based on the results of this analysis, priorities required to assess and promote the role of biochar in the development of adapted and sustainable agronomic methods. Our main findings reveal for the very first time that: (1) biochar research associated with less developed countries focused on biochar production technologies (26.5 ± 0.7%), then on biocharsâ impact on chemical soil properties (18.7 ± 1.2%), and on plant productivity (17.1 ± 2.6%); (2) China dominated biochar research activities among the medium developed countries focusing on biochar production technologies (26.8 ± 0.5%) and on use of biochar as sorbent for organic and inorganic compounds (29.1 ± 0.4%); and (3) the majority of biochar research (69.0±2.9%) was associated with highly developed countries that are able to address a higher diversity of questions. Evidently, less developed countries are eager to improve soil fertility and agricultural productivity, which requires transfer and/or translation of biochar knowledge acquired in highly developed countries. Yet, improving local research capacities and encouraging synergies across scientific disciplines and countries are crucial to foster development of sustainable agronomy in less developed countries. © 2017, The Author(s)
Biochar reduces the efficiency of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) mitigating N2O emissions
Among strategies suggested to decrease agricultural soil N2O losses, the use of nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) has been proposed. However, the efficiency of DMPP might be affected by soil amendments, such as biochar, which has been shown to reduce N2O emissions. This study evaluated the synergic effect of a woody biochar applied with DMPP on soil N2O emissions. A incubation study was conducted with a silt loam soil and a biochar obtained from Pinus taeda at 500 degrees C. Two biochar rates (0 and 2% (w/w)) and three different nitrogen treatments (unfertilized, fertilized and fertilized + DMPP) were assayed under two contrasting soil water content levels (40% and 80% of water filled pore space (WFPS)) over a 163 day incubation period. Results showed that DMPP reduced N2O emissions by reducing ammonia-oxidizing bacteria (AOB) populations and promoting the last step of denitrification (measured by the ratio nosZI + nosZII/nirS + nirK genes). Biochar mitigated N2O emissions only at 40% WFPS due to a reduction in AOB population. However, when DMPP was applied to the biochar amended soil, a counteracting effect was observed, since the N2O mitigation induced by DMPP was lower than in control soil, demonstrating that this biochar diminishes the efficiency of the DMPP both at low and high soil water contents.This work was funded by the Spanish Government (AGL2015-64582-C3-2-R MINECO/FEDER), by the Basque Government (IT-932-16) and by the European Union (FACCE-CSA no 276610/MIT04-DESIGN-UPVASC, FACCE-CSA no 2814ERA01A and 2814ERA02A). This work is also supported by the USDA/NIFA Interagency Climate Change Grant Proposal number 2014-02114 [Project number 6657-12130-002-08I, Accession number 1003011] under the Multi-Partner Call on Agricultural Greenhouse Gas Research of the FACCE-Joint Program Initiative. Any opinions, findings, or recommendation expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA. MLC was supported by a Ramon y Cajal contract from the Spanish Ministry of Economy and Competitiveness and thanks Fundacion Seneca for financing the project 19281/PI/14
Evaluating biochar and its modifications for the removal of ammonium, nitrate, and phosphate in water
Removal of nitrogen (N) and phosphorus (P) from water through the use of various sorbents is often considered an economically viable way for supplementing conventional methods. Biochar has been widely studied for its potential adsorption capabilities for soluble N and P, but the performance of different types of biochars can vary widely. In this review, we summarized the adsorption capacities of biochars in removing N (NH4-N and NO3-N) and P (PO4-P) based on the reported data, and discussed the possible mechanisms and influencing factors. In general, the NH4-N adsorption capacity of unmodified biochars is relatively low, at levels of less than 20 mg/g. This adsorption is mainly via ion exchange and/or interactions with oxygen-containing functional groups on biochar surfaces. The affinity is even lower for NO3-N, because of electrostatic repulsion by negatively charged biochar surfaces. Precipitation of PO4-P by metals/metal oxides in biochar is the primary mechanism for PO4-P removal. Biochars modified by metals have a significantly higher capacity to remove NH4-N, NO3-N, and PO4-P than unmodified biochar, due to the change in surface charge and the increase in metal oxides on the biochar surface. Ambient conditions in the aqueous phase, including temperature, pH, and co-existing ions, can significantly alter the adsorption of N and P by biochars, indicating the importance of optimal processing parameters for N and P removal. However, the release of endogenous N and P from biochar to water can impede its performance, and the presence of competing ions in water poses practical challenges for the use of biochar for nutrient removal. This review demonstrates that progress is needed to improve the performance of biochars and overcome challenges before the widespread field application of biochar for N and P removal is realized
Carbon sequestration potential and physicochemical properties differ between wildfire charcoals and slow-pyrolysis biochars
Pyrogenic carbon (PyC), produced naturally (wildfire charcoal) and anthropogenically (biochar), is extensively studied due to its importance in several disciplines, including global climate dynamics, agronomy and paleosciences. Charcoal and biochar are commonly used as analogues for each other to infer respective carbon sequestration potentials, production conditions, and environmental roles and fates. The direct comparability of corresponding natural and anthropogenic PyC, however, has never been tested. Here we compared key physicochemical properties (elemental composition, ÎŽ13C and PAHs signatures, chemical recalcitrance, density and porosity) and carbon sequestration potentials of PyC materials formed from two identical feedstocks (pine forest floor and wood) under wildfire charring- and slow-pyrolysis conditions. Wildfire charcoals were formed under higher maximum temperatures and oxygen availabilities, but much shorter heating durations than slow-pyrolysis biochars, resulting in differing physicochemical properties. These differences are particularly relevant regarding their respective roles as carbon sinks, as even the wildfire charcoals formed at the highest temperatures had lower carbon sequestration potentials than most slow-pyrolysis biochars. Our results challenge the common notion that natural charcoal and biochar are well suited as proxies for each other, and suggest that biocharâs environmental residence time may be underestimated when based on natural charcoal as a proxy, and vice versa
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