Carlos Alberto Silva

Use of biochar as bulking agent for the composting of poultry manure: Effect on organic matter degradation and humification

The aim of this study was to evaluate the use of biochar (produced by slow pyrolysis of Eucalyptus grandis biomass) as bulking agent for the composting of poultry manure. Three composting mixtures were prepared by the turned-pile system by mixing poultry manure with different organic wastes used as bulking agent (biochar, coffee husk and sawdust) in a proportion of 1:1 (fresh weight). Despite the inert nature of biochar, the composting mixture prepared with biochar underwent an organic matter degradation of 70% of the initial content. The organic matter of the poultry manure-biochar mixture was characterised by a high polymerisation degree of the humic-like substances, with a relative high proportion of humic acids in relation to fulvic acids. At the end of the composting process, the humic acid fraction represented more than 90% of the alkali extractable fraction, reflecting the intense humification of this material. Enrichment of poultry manure with biochar reduced the losses of nitrogen in the mature composts, although the use of sawdust would be more efficient in preserving the organic matter and nitrogen in the mature compost.

Evaluation of waterborne exposure to oil spill 5 years after an accident in Southern Brazil

Fish (Astyanax sp.) were exposed to water samples from the Arroio Saldanha, locality of an oil spill, and the Barigui River (upstream and downstream of the confluence of the river and Arroio Saldanha), Brazil. Histopathological and biochemical biomarkers, as acetylcholinesterase (AchE), ethoxyresorufin-O-deethylase (EROD), catalase (CAT), glutathione-S-transferase (GST) activities, lipid peroxidation (LPO) levels, and amounts of polynuclear aromatic hydrocarbon residues (PAHs) in bile were evaluated. PAHs, metals, and surfactants were investigated in the water samples. CAT and GST activities increased in the Arroio Saldanha sample, whereas CAT activity and LPO levels were increased in the upstream and downstream sites. The results suggested a toxic action of the free radicals and disturbance of the antioxidant defense mechanisms. However, the EROD and AchE activities were not affected. Histopathology studies showed severe lesions. The oil is still bioavailable to biota, moreover, other pollution sources continue to affect the water in the Barigui River.

Chemical and physical properties of organic residues

SUMMARY Due to human activity, large amounts of organic residue are generated daily.Therefore, an adequate use in agricultural activities requires the characterizationof the main properties. The chemical and physical characterization is importantwhen planning the use and management of organic residue. In this study, chemicaland physical properties of charcoal, coffee husk, pine-bark, cattle manure, chickenmanure, coconut fiber, sewage sludge, peat, and vermiculite were determined.The following properties were analyzed: N-NH 4+ , N-N0 3 - , and total concentrationsof N, P, S, K, Ca, Mg, Mn, Zn, Cu, and B, as well as pH, Electrical Conductivity (EC)and bulk density. Coffee husk, sewage sludge, chicken manure and cattle manurewere generally richer in nutrients. The EC values of these residues were also thehighest (0.08 - 40.6 dS m -1 ). Peat and sewage sludge had the highest bulky density.Sodium contents varied from 0 to 4.75 g kg -1 , with the highest levels in chickenmanure, cattle manure and sewage sludge. Great care must be taken whenestablishing proportions of organic residues in the production of substrates withcoffee husk, cattle or chicken manure or sewage sludge in the calculation of theapplied fertilizer quantity in crop fertilization programs.Index terms: substrate, organic residue, soil contamination, residue disposal.

Liberação de macronutrientes das palhadas de milheto solteiro e consorciado com feijão-de-porco sob cultivo de feijão

Nutrients recycle is related to the absorption capacity by different cover crop species. Already speeds of decomposition and of nutrient release of straws produced is mostly related with C/N ratio, with a marked difference between grasses and leguminous. In this sense, the objective of this study was to evaluate the biomass production and macronutrient contents and accumulation, decomposition, and nutrient release from straw of millet (Pennisetum typhoides (Burm.) Stapf) and millet - jack - bean (Canavalia ensiformes (L.) DC.) intercropping, under field conditions, under common bean, sown in August (winter/spring). Decomposition and nutrient release was determined in nylon bags (0.2 x 0.2 m, 1 mm mesh) filled with straw quantities according to the area of the bag. The experimental design was randomized blocks with four replications in split plot arrangement. The straws represented the plots and the subplots evaluation periods (0, 8, 16, 24, 40, 56, and 72 days). The residues were dried to constant weight in a forced-air oven at 65 oC to determine the remaining dry matter, then ground and sent to a laboratory to analyze macronutrient contents. Based on the contents and remaining dry matter amounts, the remaining nutrient amounts were determined, expressed in relation to the initial amount. Non-linear models were fit to the values, choosing the best adjustment in each case. Biomass quantity, N and Ca contents and cycling of nutrient quantities was greatest in the intercropping straw. The decomposition and nutrient release speeds were also highest in millet - jack - bean intercropping straw.

Matrix effect on the performance of headspace solid phase microextraction method for the analysis of target volatile organic compounds (VOCs) in environmental samples

Solid phase microextraction (SPME) is a fast, cheap and solvent free methodology widely used for environmental analysis. A SPME methodology has been optimized for the analysis of VOCs in a range of matrices covering different soils of varying textures, organic matrices from manures and composts from different origins, and biochars. The performance of the technique was compared for the different matrices spiked with a multicomponent VOC mixture, selected to cover different VOC groups of environmental relevance (ketone, terpene, alcohol, aliphatic hydrocarbons and alkylbenzenes). VOC recovery was dependent on the nature itself of the VOC and the matrix characteristics. The SPME analysis of non-polar compounds, such as alkylbenzenes, terpenes and aliphatic hydrocarbons, was markedly affected by the type of matrix as a consequence of the competition for the adsorption sites in the SPME fiber. These non-polar compounds were strongly retained in the biochar surfaces limiting the use of SPME for this type of matrices. However, this adsorption capacity was not evident when biochar had undergone a weathering/aging process through composting. Polar compounds (alcohol and ketone) showed a similar behavior in all matrices, as a consequence of the hydrophilic characteristics, affected by water content in the matrix. SPME showed a good performance for soils and organic matrices especially for non-polar compounds, achieving a limit of detection (LD) and limit of quantification (LQ) of 0.02 and 0.03 ng g(-1) for non-polar compounds and poor extraction for more hydrophilic and polar compounds (LD and LQ higher 310 and 490 ng g(-1)). The characteristics of the matrix, especially pH and organic matter, had a marked impact on SPME, due to the competition of the analytes for active sites in the fiber, but VOC biodegradation should not be discarded in matrices with active microbial biomass.

Métodos de quantificação de carbono e matéria orgânica em resíduos orgânicos

Na determinacao dos teores de carbono (C) em residuos orgânicos, sao utilizadas variacoes de marchas analiticas empregadas para solos, sem a necessaria calibracao. Assim, torna-se necessario avaliar e calibrar metodos de determinacao dos teores de C e de materia orgânica (MO) nesses materiais, tendo como referencia o metodo da combustao seca. Objetivou-se neste estudo: avaliar metodos de determinacao dos teores de carbono total (CT), carbono orgânico (CO) e MO em amostras de residuos orgânicos diversificadas; determinar um modelo matematico de conversao de C e MO de um metodo analitico para outro; e avaliar a possibilidade de o metodo da mufla ser utilizado em rotina de laboratorios para analise de teores de MO e inferencia de teores de CT em residuos orgânicos. Foram avaliados os teores de CT, CO e MO em 42 amostras de compostos, estercos, residuos vegetais, lodos de esgoto e camas de frango e de suino, cujas coletas foram realizadas em 2010, em municipios do Sul de Minas Gerais e em Jundiai-SP. As amostras foram secas em estufa a 65 oC, por 48 h, maceradas e passadas em peneiras com malha de 0,250 mm e analisadas. Os metodos utilizados nas analises foram: Walkley-Black modificado - Yeomans & Bremner (YB), combustao seca a 950 oC (analisador TOC) e combustao em mufla a 550 oC, para as determinacoes de CO, CT e MO, respectivamente. Os teores de CT nos residuos orgânicos variaram de 8,5 a 51,4 %. O metodo de Yeomans & Bremner subestima os teores de C em relacao ao metodo da combustao seca. Em funcao da determinacao dos teores de MO e CO e de uso de equacoes matematicas, e possivel estimar os teores de CT pelo metodo da combustao seca.

Spatial variability of soil acidity attributes and the spatialization of liming requirement for corn

In Brazil, technicians, in most cases, ignore the aspects related to the spatial variability of the soil acidity attributes when liming requirement is calculated. The objective of this study was to validate the liming practice, evaluating the presence of spatial variability of the soil acidity attributes and the existence of areas with differentiated liming requirement, which were calculated by different methods. The experiment was carried out in an area cultivated with corn under conventional management and irrigation. The soil (0-0.2 m) was sampled in a conventional way (composite soil sample) and in a systematic scheme, by use of a grid sampling. In sequence to the soil fertility attributes analysis, it was calculated the liming requirement, according to the methods of SMP pH, aluminum neutralization and elevation of soil Ca and Mg levels, and increase of the soil base saturation. After the descriptive analysis of the data set was accomplished, the semivariograms were calculated and the maps were obtained through the kriging technique. Absence of spatial dependence, as well as the non necessity of limestone application, was observed for the Al neutralization calculation method. Spatial dependence was only verified for the soil acidity attributes and to the liming requirement calculated by the base saturation and SMP pH methods; for these two methods, the semivariogram ranges obtained varied from 35.7 to 200.5 m. The results have highlighted the existence of differentiated liming requirement zones when the variability of the soil acidity attributes was considered in the calculation of the dose and type of limestone to be used for corn soil acidity correction.

Fourier transform infrared spectroscopy and partial least square regression for the prediction of substrate maturity indexes

Traditional methods to evaluate the stability and maturity of organic wastes and composting matrices are laborious, time-consuming and generate laboratory chemical wastes. This study focused on the development of partial least square (PLS) regression models for the prediction of the stability and maturity of compost-based substrates based on Fourier transform infrared (FTIR) spectroscopy. The following parameters, selected as conventional maturity indexes, were modeled and used as dataset: dissolved organic carbon (DOC), C/N and NH4(+)/NO3(-) ratios, cation exchange capacity (CEC), degree of polymerization (DP), percentage of humic acid (PHA), humification index (HI) and humification ratio (HR). Models were obtained by using data from a wide range of compost based growing media of diverse origin and composition, including 4 commercially available substrates and 11 substrates prepared in our facilities with varying proportions of different organic wastes. The PLS models presented correlation coefficient of calibration (R(2)cal) close to 0.90 and correlation coefficient (R(2)) of cross validation (R(2)cv) presented acceptable values (>0.6), ranging from 0.67 (HR) to 0.92 (C/N). The good performance of the method was also confirmed by the low correlation obtained from the Y-randomization test. R(2) for test samples (R(2)pred) ranged from 0.66 (C/N) to 0.97 (HI) confirming the good correlation between measured and PLS predicted maturity indexes. FTIR spectroscopy combined with PLS regression represents, after modeling process, a fast and alternative method to assess substrate maturity and stability with reduction of time, lower generation of laboratory chemical wastes residues and lower cost per sample than conventional chemical methods. All models adjusted for maturity indexes are predictive, robust and did not present chance correlation.

Carbon pool ratios as scientific support to field morphology in the differentiation of dark subsurface soil horizons

In soil surveys, it is usual to find profiles with an uncommon disposition of horizons. Dark horizons in depth might be either the consequence of erosion and redeposition of soil materials from upslope or an indication of the podzolization process, which forms a spodic horizon. Few laboratory analyses are known to characterize dark subsurface horizons which could allow for the differentiation of spodic from buried A horizons. Some researchers propose C-humic and C-fulvic acid fraction ratios and forms of carbon to analyze characteristics of these horizons. Therefore, this research aimed to characterize dark subsurface horizons found in soils under a Eucalyptus minimum tillage system in the state of Rio Grande do Sul, Brazil, and to relate soil organic carbon to landscape features in toposequences. The characterization was performed by using the following ratios: humic acid and fulvic acid fractions (Cha/Cfa); pyrophosphate extractable-C and organic carbon (Cp/OC); fulvic acid fraction and pyrophosphate extractable-C (Cfa/Cp), and fulvic acid fraction and organic carbon (Cfa/OC). Soil organic carbon was related to slope gradient and Geomorphons in a Geographic Information System (GIS). None of the horizons analyzed met the criteria required for spodic horizon classification, where Cha/Cfa < 0.50, Cfa/OC < 0.30, and the ratio Cp/OC ≥ 0.50 simultaneously with Cfa/Cp ≥ 0.50. A relationship was found between landscape features and soil organic carbon content. The methodology proved to be satisfactory for providing scientific support to field morphology classification of dark subsurface horizons, specifically in the case where they could be misinterpreted as spodic horizons.

Physico-Chemical Evaluation of Organic Wastes Compost-Based Substrates for Eucalyptus Seedlings Growth

ABSTRACT Eucalyptus growth was evaluated in five compost-based substrates formulated with different proportions of sewage sludge, coffee husk, peat, chicken manure, cattle manure, pine bark, sawdust, and coconut fiber, compared to two commercial substrates (CS). Organic wastes compost-based substrates (OWS) and CS were characterized regarding the available contents of macro and micronutrients, sodium (Na+), pH, electrical conductivity (EC), and bulk density (BD). Substrate attributes and eucalyptus biomass production were submitted to principal component analysis (PCA) to detect patterns of clustering. The different proportions of organic wastes influenced the physico-chemical characteristics of OWS and, consequently, the eucalyptus biomass production. The highest biomass was observed in one of the CS that is rich in available boron (B) and calcium (Ca), less concentrated in most of the nutrients and with low EC and Na+ contents. The PCA allowed the verification that B availability was the attribute that explained most of the variation in eucalyptus biomass production.