1,721,000 research outputs found
The impact of crop plant residues on carbon sequestration in soil : a useful strategy to balance the atmospheric CO2
No full textAnthropogenic emission of CO2 and other greenhouse gases was rapidly increased with the Industrial Revolution and this event has caused a world interest in identifying strategies of reducing the rate of gaseous emission. The intergovernmental Panel on Climate Change shows that from 1850 and 1998 the emission from terrestrial ecosystem was about half of fossil fuel combustion. Agriculture can be a source or sink for atmospheric CO2 because soil organic carbon pool (SOCP) in soil surface is sensitive to changes in land use and soil management practice. The carbon sink capacity of the world agricultural and degraded soils is 50-66% of the historic carbon loss that are of 42 to 78 Gt of carbon respectively. Carbon (C) sequestration implies transferring atmospheric CO2 into long-lived pools and subsequent storage of fixed C as soil organic carbon (SOC). In this way the conservation of plant residues in agricultural soil play an important role in CO2 sequestration. The mechanism by which crop residues contribute to SOC is through their chemical, phisical and biological stabilization. In this chapter we discussed the role of the plant residues in the carbon sequestration throughout plant tissue stabilization in soil, giving a new approach and understanding of the plant residue conservation in soil
Degradation of aflatoxin B1 during anaerobic digestion and its effect on process stability
No full textThe effect of aflatoxin B1 (AFB1) on an anaerobic digestion process (AD) was studied. Batch anaerobic digestion trials were performed with both non-contaminated AFB1 corn grain (Control A) and contaminated-AFB1 corn grain at different doses (AFB1 contents of 0.54, 66.2, and 110μgkg-1 wet weight). Both cumulative biogas production and the degradation rate of AFB1 were studied. Results indicated that no adverse effects on AD were detected during the processes which could be attributed to the presence of AFB1. AFB1 degradation ranged from 69% to 87% of the total initial AFB1 content. Anaerobic digestion trials using Completely Stirred Tank Reactors (CSTR) were also carried out, comparing the biogas production of a mix of contaminated corn grain plus pig slurry (AFB1 content of 7.2μgkg-1 wet weight) with a mix of non-contaminated corn grain plus pig slurry (Control B). No adverse effect of AFB1 on biogas production was detected. The CSTR trial resulted in an average degradation of AFB1 of 42%. The further storage of the digestate for 30 days resulted in an overall degradation (CSTR plus storage) of AFB1 of 61% of the starting content
Influenza delle vie biosintetiche della lignina in piante di mais “wild type” e brown midrib 3 (bm3) sulla formazione e conservazione nel suolo di molecole umo-simili
No full textNitrogen and water recovery from animal slurries by a new integrated ultrafiltration, reverse osmosis and cold stripping process: a case study
No full textThe correct management of livestock manure represents one of the major challenge for the agricultural sector development, as it may ensure environmental and economic sustainability of livestock farming. In this work, a new treatment process called N-Free®, was monitored on two plants treating digested cattle manure (DCM) and digested swine manure (DSM). The process is characterized by sequential integration of solid/liquid separations, ultrafiltration, reverse osmosis and cold ammonia stripping. Solid and liquid streams were characterized regarding TS, TKN, N-NH4+, P and K content allowing to draw a complete mass balance. The main results were a substantial reduction of initial digestate volume (38 and 51% in DCM and DSM respectively) as clean water and a high N-NH4+ removal percentage (47 and 71% in DCM and DSM respectively), through cold ammonia stripping, allowing the production of up to 1.8m3 concentrated ammonium sulfate, every 100m3 of treated digestate. The concentrated streams, rich in either organic or mineral N, P and K, can be efficiently used for land application. The N-Free® technology demonstrated to be a valuable candidate for the path toward nutrient and water recycle, in a new sustainable agriculture and farming concept
Studying soil organic matter using 13C CP-MAS NMR : The effect of soil chemical pre-treatments on spectra quality and representativity
No full text13C CP-MAS NMR spectroscopy is a technique that has proved to be useful in studying soil organic matter (SOM). Nevertheless, NMR spectra exhibit a weak signal and have very low resolution due to: the low natural abundance of 13C (1.1 % of C) in SOM, the generally low SOM content of soils, and the presence of paramagnetic impurities. This paper studies the effects of soil chemical pre-treatments on 13CP-MAS NMR spectra quality and spectra representativity i.e. soil C mass balance. After chemical pre-treatment to increase total organic carbon (TOC) content and C/Fe ratio, eight soils characterized by different levels of organic carbon content and C/Fe ratios were studied using 13CP-MAS NMR. Moreover, where chemical treatments were not applicable due to high carbon losses, the number of 13CP-MAS NMR scans was increased in order to obtain satisfactory spectra. Results show that chemical pre-treatment of soils with C/Fe > 1 caused high C losses. Bulk soils were therefore studied by increasing the number of 13CP-MAS NMR scans. Acceptable spectra were obtained from 8K scans (1K = 1024 transient). On the other hand, even when a large number of scan (32K) are used, soil with C/Fe < 1 cannot be studied. As these soils are characterized by low C losses after HCl treatments (range of 2.9–25.4%), a pre-treatment of at least 1.39 mol l 1 HCl removes excess Fe and at the same time increases C/Fe ratio resulting in 32K scans providing good spectra
Fresh organic matter of municipal solid waste enhances phytoextraction of heavy metals from contaminated soil
No full textIn this study, the ability of the organic fraction of municipal solid wastes (OFMSW) to enhance heavy metal uptake of maize shoots compared with ethylenediamine disuccinic acid (EDDS) was tested on soil contaminated with heavy metals. Soils treated with OFMSW and EDDS significantly increased the concentration of heavy metals in maize shoots (increments of 302%, 66%, 184%, 169%, and 23% for Cr, Cu, Ni, Zn, and Pb with respect to the control and increments of 933%, 482%, 928%, 428%, and 5551% for soils treated with OFMSW and EDDS, respectively). In soil treated with OFMSW, metal uptake was favored because of the high presence of dissolved organic matter (DOM) (41.6× than soil control) that exhibited ligand properties because of the high presence of carboxylic acids. Because of the toxic effect of EDDS on maize plants, soil treated with OFMSW achieved the highest extraction of total heavy metals
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