Estimating subsoil resistance to nitrate leaching from easily measurable pedological properties

Leaching of nitrate (NO3-) can increase the groundwater concentration of this anion and reduce the agronomical effectiveness of nitrogen fertilizers. The main soil property inversely related to NO3- leaching is the anion exchange capacity (AEC), whose determination is however too time-consuming for being carried out in soil testing laboratories. For this reason, this study evaluated if more easily measurable soil properties could be used to estimate the resistance of subsoils to NO3- leaching. Samples from the subsurface layer (20-40 cm) of 24 representative soils of São Paulo State were characterized for particle-size distribution and for chemical and electrochemical properties. The subsoil content of adsorbed NO3- was calculated from the difference between the NO3- contents extracted with 1 mol L-1 KCl and with water; furthermore, NO3- leaching was studied in miscible displacement experiments. The results of both adsorption and leaching experiments were consistent with the well-known role exerted by AEC on the nitrate behavior in weathered soils. Multiple regression analysis indicated that in subsoils with (i) low values of remaining phosphorus (Prem), (ii) low soil pH values measured in water (pH H2O), and (iii) high pH values measured in 1 moL L-1 KCl (pH KCl), the amounts of surface positive charges tend to be greater. For this reason, NO3- leaching tends to be slower in these subsoils, even under saturated flow condition.

Boron Leaching Decreases withIncreases on Soil pH

ABSTRACT Management of boron fertilization depends on the magnitude of B leaching in the soil profile, which varies proportionally with the concentration of B in the soil solution, which, in turn, decreases as the soil pH increases due to the higher sorption of B on soil solid surfaces. The objective of this study was to quantify the effect of liming and rates of B applied to the soil on B leaching. The experiment was carried out in the laboratory in 2012, and treatments consisted of a factorial combination of two rates of liming (without and with lime to raise the soil pH to 6.0) and five rates of B (0, 10, 20, 50 and 100 mg kg-1, as boric acid). A Typic Rhodudalf was used, containing 790 g kg-1 clay and 23 g kg-1 organic matter; the pH(H2O) was 4.6. Experimental units were composed of PVC leaching columns (0.10 m in diameter) containing 1.42 kg of soil (dry base). Boron was manually mixed with the top 0.15 m of the soil. After that, every seven days for 15 weeks, 300 mL of distilled water were added to the top of each column. In the percolated solution, both the volume and concentration of B were measured. Leaching of B decreased with increased soil pH and, averaged across the B rates applied, was 58 % higher from unlimed (pH 4.6) than from limed (pH 6.6) samples as a result of the increase in B sorption with higher soil pH. In spite of its high vertical mobility, the residual effect of B was high in this oxisol, mainly in the limed samples where 80 % of B applied at the two highest rates remained in the soil, even after 15 water percolations. Total recovery of applied B, including leached B plus B extracted from the soil after all percolations, was less than 50 %, showing that not all sorbed B was quantified by the hot water extraction method.

The importance of pre-treatment of spent hydrotreating catalysts on metals recovery

This work describes a three-step pre-treatment route for processing spent commercial NiMo/Al2O3 catalysts. Extraction of soluble coke with n-hexane and/or leaching of foulant elements with oxalic acid were performed before burning insoluble coke under air. Oxidized catalysts were leached with 9 mol L-1 sulfuric acid. Iron was the only foulant element partially leached by oxalic acid. The amount of insoluble matter in sulfuric acid was drastically reduced when iron and/or soluble coke were previously removed. Losses of active phase metals (Ni, Mo) during leaching with oxalic acid were compensated by the increase of their recovery in the sulfuric acid leachate.

Poultry carcass decomposition and physicochemical analysis of compounds in different Composter types

This study aimed to assess five composter types in poultry carcasses decomposition and to perform a physicochemical analysis of the compounds obtained. Composter types used were six-hole brick, wood, screen, windrow with three PVC pipes with six holes and windrow with three PVC pipes with 10 holes. Composting was followed by four periods using wood shaving like substrate with one bird carcass placed in each composter. Pile turning was performed every 10 days and temperature in each layer was measured on 1st, 7th, 14th, 19th and 29th day, at 3 p.m., as well as room temperature. Temperature during pile turning was also measured at five points per layer and carcass weighing performed to calculate decomposition percentage. Physicochemical parameters evaluated in substrates were moisture, ash, phosphorus, potassium, nitrogen, pH, organic carbon and C/N ratio, up to 30 days. Data were analyzed by repeated measures model, using MIXED method of SAS software. All values of final physicochemical composition of substrates were found according to values of IN-25, except nitrogen. The composter types were efficient in decomposition of poultry carcasses.

Sanitary quality of broiler litter reused

ABSTRACT Considering the importance of the substrate to bedding in the poultry industry in Brazil, and the enormous pressure on environmental management as to the correct use and management of the waste generated by the production sector, this study aimed to analyze the effect of reuses of two types of litter on sanitary qualities and productive performance of broilers. The study was conducted with litter from 32 different broiler houses, two types of substrates and four cycles of reuses. The litter sanitary quality was verified by the identification of the presence of Escherichia coli and Salmonellaspp. and the incidence of footpad dermatitis. It was observed that the coffee hulls litter presented a reduction of 28.61 percentage points in the probability of occurrence of Salmonella spp when compared to the wood shavings litter, nevertheless, no statistical difference was observed on bacterial occurrence with Salmonella spp. for litter of different types or numbers of reutilization. The presence of Escherichia coli was detected in litter of all cycles, for both types of substrate. The occurrence of footpad lesions was detected for both types of litter, and was influenced by the number of reutilization cycles of the litter. The degree of incidence was detected only for the litter with coffee hull in which there was an increase of 30% between the first and second reuse from which tended to stabilize.

Modification of pyruvate kinase and lactate dehydrogenase in foot muscle of the sea mussel Mytilus galloprovincialis under anaerobiosis and recovery

The modification of pyruvate kinase (PK) and lactate dehydrogenase (LDH) activity in foot muscle of the mussel Mytilus galloprovincialis during exposure to air and recovery in water was investigated. In the course of exposure to air, the activity of these enzymes measured at high and low substrate concentrations showed successive increases and decreases. Returning the mussels to water after exposure to air affected enzyme activity in a manner similar to anaerobiosis. When measuring at saturated concentrations of substrates and substrate and coenzyme for PK and LDH, respectively, the maximum activation of PK (37%) was observed at 4 h of animal exposure to air, and for LDH (67%) at 6 h exposure to air. During 24 h of exposure of animals to air, PK activity practically reached the stock level, while LDH was still activated (148%). The change in lactate dehydrogenase activity in mussel muscle during anoxia and recovery is described here for the first time. Variation in pyruvate kinase activity during exposure to air and recovery is linked to the alteration of half-maximal saturation constants and maximal velocity for both substrates. The possible role of reversible phosphorylation in the regulation of pyruvate kinase and lactate dehydrogenase properties is discussed

Contribution of matrix vesicles and alkaline phosphatase to ectopic bone formation

Endochondral calcification involves the participation of matrix vesicles (MVs), but it remains unclear whether calcification ectopically induced by implants of demineralized bone matrix also proceeds via MVs. Ectopic bone formation was induced by implanting rat demineralized diaphyseal bone matrix into the dorsal subcutaneous tissue of Wistar rats and was examined histologically and biochemically. Budding of MVs from chondrocytes was observed to serve as nucleation sites for mineralization during induced ectopic osteogenesis, presenting a diameter with Gaussian distribution with a median of 306 ± 103 nm. While the role of tissue-nonspecific alkaline phosphatase (TNAP) during mineralization involves hydrolysis of inorganic pyrophosphate (PPi), it is unclear how the microenvironment of MV may affect the ability of TNAP to hydrolyze the variety of substrates present at sites of mineralization. We show that the implants contain high levels of TNAP capable of hydrolyzing p-nitrophenylphosphate (pNPP), ATP and PPi. The catalytic properties of glycosyl phosphatidylinositol-anchored, polidocanol-solubilized and phosphatidylinositol-specific phospholipase C-released TNAP were compared using pNPP, ATP and PPi as substrates. While the enzymatic efficiency (k cat/Km) remained comparable between polidocanol-solubilized and membrane-bound TNAP for all three substrates, the k cat/Km for the phosphatidylinositol-specific phospholipase C-solubilized enzyme increased approximately 108-, 56-, and 556-fold for pNPP, ATP and PPi, respectively, compared to the membrane-bound enzyme. Our data are consistent with the involvement of MVs during ectopic calcification and also suggest that the location of TNAP on the membrane of MVs may play a role in determining substrate selectivity in this micro-compartment.

The use of film coating on the performance of treated corn seed

The main objective of seed coating technology using polymers is to improve the physical, physiological and sanitary characteristics of seed performance. The objectives of the present study were to determine: the plantability of corn seeds treated with insecticide, fungicide and graphite, covered with a film coating; the dust retention on treated corn seeds; and the leaching of applied products on corn seeds covered by a film coating. Seed plantability was determined by counting the skips and double seeds; dust was determined by using fiberglass paper in mg.100 g-1 of seeds; and the leaching was determined by collecting the material leached in a 10 cm layer of sand after irrigation. The following conclusions were made: seeds covered with film coating effectively reduce skips and double seeds; film coating effectively reduces the formation of dust from the seeds; film coated seeds minimize the leaching of the insecticide applied in seed treatment; and there are differences in effectiveness related to film coating type and dosage.

Ecologia de Xylocopa (Neoxylocopa) cearensis (Hymenoptera, Anthophoridae) nas dunas litorâneas de Abaeté, Salvador, Bahia

The study was carried out in a 8.2 ha area in an environmental protection area of tropical sea coastal sand dune with "restinga" vegetation in Salvador, Bahia, northeastern Brazil. A total of 1760 bees of Xylocopa (Neoxylocopa) cearensis Ducke, 1910 were netted during the whole year on flowers of 43 plant species belonging to 26 botanic families. The majority of the individuals (79%) concentrated their foraging activity in five plant species. Individuals foraged all day long being the greatest activity between 8 h and 14 h. Similar proportions of young and old bees were sampled over the year. The density of substrates used for nesting was 4.56/ha. In total, 94% of the nests were found in branches of Agaristha revoluta (Spr.) DC. (Ericaceae). The great occurrence (68.7%) of old perforations indicates that the nests were used twice or more times by bees.

Fertilizer 15N balance in a coffee cropping system: a case study in Brazil

Knowledge about the fate of fertilizer nitrogen in agricultural systems is essential for the improvement of management practices in order to maximize nitrogen (N) recovery by the crop and reduce N losses from the system to a minimum. This study involves fertilizer management practices using the 15N isotope label applied in a single rate to determine the fertilizer-N balance in a particular soil-coffee-atmosphere system and to deepen the understanding of N plant dynamics. Five replicates consisting of plots of about 120 plants each were randomly defined within a 0.2 ha coffee plantation planted in 2001, in Piracicaba, SP, Brazil. Nine plants of each plot were separated in sub-plots for the 15N balance studies and treated with N rates of 280 and 350 kg ha-1 during 2003/2004 and 2004/2005, respectively, both of them as ammonium sulfate enriched to a 15N abundance of 2.072 atom %. Plant shoots were considered as separate parts: the orthotropic central branch, productive branches, leaves of productive branches, vegetative branches, leaves of vegetative branches and fruit. Litter, consisting of dead leaves accumulated below the plant canopy, was measured by the difference between leaves at harvest and at the beginning of the following flowering. Roots and soil were sampled down to a depth of 1.0 at intervals of 0.2 m. Samples from the isotopic sub-plots were used to evaluate total N and 15N, and plants outside sub-plots were used to evaluate dry matter. Volatilization losses of NH3 were estimated using special collectors. Leaching of fertilizer-N was estimated from deep drainage water fluxes and 15N concentrations of the soil solution at 1 m soil depth. At the end of the 2-year evaluation, the recovery of 15N applied as ammonium sulfate was 19.1 % in aerial plant parts, 9.4 % in the roots, 23.8 % in the litter, 26.3 % in the fruit and 12.6 % remaining in the 0_1.0 m soil profile. Annual leaching and volatilization losses were very small (2.0 % and 0.9 %, respectively). After two years, only 6.2 % N were missing in the balance (100 %) which can be attributed to other non-estimated compartments and experimental errors. Results show that an enrichment of only 2 % atom 15N allows the study of the partition of fertilizer-N in a perennial crop such as coffee during a period of two years.

Closed soilless growing system for producing strawberry bare root transplants and runner tips

The objective of this work was to test a closed soilless growing system for producing bare root transplants and runner tips of two strawberry clones, using two categories of substrates. The system used corrugated roofing panels of fiber-cement, over which a substrate layer was used as a growing bed. The nutrient solution was pumped from a reservoir toward the upper end of the roofing panels and drained back to a reservoir. Plant growth and development were determined for two advanced strawberry clones, grown in sand or in Plantmax organic substrate. Growth of the stock plants and the number and dry mass of bare root transplants were similar in the substrates, but bare roots differed in their crown diameters by substrate. For number of runner tips, no significant differences were found in total, small, and medium categories in the substrates. A mean production of about 590 runner tips per square meter and 145 bare root transplants per square meter was obtained. For both clones, a large number of bare root transplants and runner tips of adequate size were produced in the closed soilless growing system using sand or organic substrate.

Modificação de zeólitas para uso em catálise

The use of zeolites and other molecular sieves as catalysts is discussed at an introductory level. The text includes a brief historic background on the use of zeolites in catalysis, and a discussion of some chemical and physical properties of silicalite, aluminosilicate, and aluminophosphate molecular sieves. The strategies currently used to chemically modify zeolites and related materials to produce catalysts with increased activity and selectivity are discussed, including the use of redox molecular sieves for hydrocarbon oxidation and the leaching of the active metals from the support.

Uso de membranas de Nafion para a construção de sensores ópticos para medidas de pH

The behaviour of Nafion® polymeric membranes containing acid-base dyes, bromothymol blue (BB) and methyl violet (MV), were studied aiming at constructing an optical sensor for pH measurement. BB revealed to be inadequate for developing sensing phases due to the electrostatic repulsion between negative groups of their molecules and the negative charge of the sulfonate group of the Nafion®, which causes leaching of the dye from the membrane. On the other hand, MV showed to be suitable due to the presence of positive groups in its structure. The membrane prepared from a methanolic solution whose Nafion®/dye molar ratio was 20 presented the best analytical properties, changing its color from green to violet in the pH range from 0.6 to 3.0. The membrane can be prepared with good reproducibility, presenting durability of ca. 6 months and response time of 22 s, making possible its use for pH determination in flow analysis systems.

Cerâmicas bioativas: estado da arte

Bioactive glasses undergo corrosion with leaching of alkaline ions when exposed to body fluids. This results in the spontaneous formation of a layer of hydroxyapatite (HA), the mineral component of natural bone, which in turn can induce bone growth in vivo. This paper describes the different types of bioactive glasses, the characterization methods currently used, and the main factors that influence their bioactivity. Nucleation and crystallization, the main mechanisms involved in the formation of hydroxyapatite, Ca10(PO4)6(OH)2, are discussed as a function of the chemical composition and the reactivity of the surface of the material. Finally, promising applications are considered.

Comportamento de zinco e manganês de pilhas alcalinas em uma coluna de solo

The aim of this study was to evaluate the behavior of Zn and Mn in a soil column. Two soil columns were sampled, and four opened alkaline batteries were placed at the top of one soil column. An acid-rainwater solution (HNO3 and H2SO4; pH 4) was percolated through the battery contaminated column during one year. The results showed that the leaching of alkaline batteries caused enrichment of 70 and 11 times in the Zn and Mn concentration of the topsoil, respectively. Additionally, leaching of electrolyte (KOH) from the batteries increased the soil pH in the contaminated column.