Ammonium chloride as nitrogen source in sugarcane harvested without burning

The great difficulty of incorporation of N fertilizers into the "green sugarcane" system causes concern and since urea is the most commonly used source, there is the risk of loosing NH3 through volatilization. For this reason, a field experiment was undertaken (in a Hapludox Typic) with the objective of evaluating the agronomic efficiency of ammonium chloride on stubble of the second ratoon (SP89 1115), as well as its residual effect on the subsequent cycle (third ratoon). The experimental design was randomized blocks with four replications. Treatments consisted of three N rates (60, 120 and 180 kg ha-1 N) in the form of NH4Cl, in addition to a control treatment without the addition of N fertilizer. The ratoon cane of the second cutting was harvested in November 2006 and the treatments were applied in December 2006. The second ratoon was harvested mechanically in November 2007 and in December 2007, 450 kg ha-1 of the NPK mixture 20-05-19 was applied, providing 90, 22 and 86 kg ha-1 N, P2O5 and K2O, respectively, for the purpose of evaluating the effect of residual-N from the treatments implanted in December 2006. An increase in the rates of N-NH4Cl had a positive effect on the leaf concentrations of P, Mg and S. Stalk yield (MSS - Mg ha-1 of sugarcane stalks) and sugar (MSH - Mg ha-1 of sucrose) in the November 2006 harvest responded linearly to the increase of N doses in the form of NH4Cl. In relation to the effect of residual-N in the 2007/2008 harvest, it was observed, in general, that the concentrations of macronutrients in the sugarcane leaf +1 were within the range considered adequate in the state of São Paulo, Brazil. The residual-N of the NH4Cl doses resulted in a significant reduction in stalk (MSS) and sugar (MSH) production. It may be concluded that the NH4Cl source at a dose of 120 kg ha-1 N in ratoon fertilization of the second cutting was agronomically efficient, presenting, however, less efficiency of residual-N in the subsequent cycle.

Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols) treated with different phosphorus rates and sources for varied soil-source contact periods

Despite the large number of studies addressing the quantification of phosphorus (P) availability by different extraction methods, many questions remain unanswered. The aim of this paper was to compare the effectiveness of the extractors Mehlich-1, Anionic Resin (AR) and Mixed Resin (MR), to determine the availability of P under different experimental conditions. The laboratory study was arranged in randomized blocks in a [(3 x 3 x 2) + 3] x 4 factorial design, with four replications, testing the response of three soils with different texture: a very clayey Red Latosol (LV), a sandy clay loam Red Yellow Latosol (LVA), and a sandy loam Yellow Latosol (LA), to three sources (triple superphosphate, reactive phosphate rock from Gafsa-Tunisia; and natural phosphate from Araxá-Minas Gerais) at two P rates (75 and 150 mg dm-3), plus three control treatments (each soil without P application) after four contact periods (15, 30, 60, and 120 days) of the P sources with soil. The soil acidity of LV and LVA was adjusted by raising base saturation to 60 % with the application of CaCO3 and MgCO3 at a 4:1 molar ratio (LA required no correction). These samples were maintained at field moisture capacity for 30 days. After the contact periods, the samples were collected to quantify the available P concentrations by the three extractants. In general, all three indicated that the available P-content in soils was reduced after longer contact periods with the P sources. Of the three sources, this reduction was most pronounced for triple superphosphate, intermediate for reactive phosphate, while Araxá phosphate was least sensitive to the effect of time. It was observed that AR extracted lower P levels from all three soils when the sources were phosphate rocks, while MR extracted values close to Mehlich-1 in LV (clay) and LVA (medium texture) for reactive phosphate. For Araxá phosphate, much higher P values were determined by Mehlich-1 than by the resins, because of the acidity of the extractor. For triple superphosphate, both resins extracted higher P levels than Mehlich-1, due to the consumption of this extractor, particularly when used for LV and LVA.

Methane fluxes from waterlogged and drained Histosols of highland areas

Soil can be either source or sink of methane (CH4), depending on the balance between methanogenesis and methanotrophy, which are determined by pedological, climatic and management factors. The objective of this study was to assess the impact of drainage of a highland Haplic Histosol on CH4 fluxes. Field research was carried out in Ponta Grossa (Paraná, Brazil) based on the measurement of CH4 fluxes by the static chamber method in natural and drained Histosol, over one year (17 sampling events). The natural Histosol showed net CH4 eflux, with rates varying from 238 µg m-2 h-1 CH4, in cool/cold periods, to 2,850 µg m-2 h-1 CH4, in warm/hot periods, resulting a cumulative emission of 116 kg ha-1 yr-1 CH4. In the opposite, the drained Histosol showed net influx of CH4 (-39 to -146 µg m-2 h-1), which resulted in a net consumption of 9 kg ha-1 yr-1 CH4. The main driving factors of CH4 consumption in the drained soil were the lowering of the water-table (on average -57 cm, vs -7 cm in natural soil) and the lower water content in the 0-10 cm layer (average of 5.5 kg kg-1, vs 9.9 kg kg-1 in natural soil). Although waterlogged Histosols of highland areas are regarded as CH4 sources, they fulfill fundamental functions in the ecosystem, such as the accumulation of organic carbon (581 Mg ha-1 C to a depth of 1 m) and water (8.6 million L ha-1 = 860 mm to a depth of 1 m). For this reason, these soils must not be drained as an alternative to mitigate CH4 emission, but effectively preserved.

PEASANT AND SCIENTIFIC KNOWLEDGE ON PLANOSOLS AS A SOURCE OF MATERIALS IN THE MAKING OF NON-INDUSTRIAL POTTERY

Ethnopedological studies have mainly focused on agricultural land uses and associated practices. Nevertheless, peasant and indigenous populations use soil and land resources for a number of additional purposes, including pottery. In the present study, we describe and analyze folk knowledge related to the use of soils in non-industrial pottery making by peasant potters, in the municipality of Altinho, Pernambuco State, semiarid region at Brazil. Ethnoscientific techniques were used to record local knowledge, with an emphasis on describing the soil materials recognized by the potters, the properties they used to identify those soil materials, and the criteria employed by them to differentiate and relate such materials. The potters recognized three categories of soil materials: “terra” (earth), “barro” (clay) and, “piçarro” (soft rock). The multi-layered arrangement of these materials within the soil profiles was similar to the arrangement of the soil horizon described by formal pedologists. “Barro vermelho” (red clay) was considered by potters as the principal ceramic resource. The potters followed morphological and utilitarian criteria in distinguishing the different soil materials. Soils from all of these sites were sodium-affected Alfisols and correspond to Typic Albaqualf and Typic Natraqualf in the Soil Taxonomy (Soil Survey Staff, 2010).

Sheep Excreta as Source of Nitrous Oxide in Ryegrass Pasture in Southern Brazil

ABSTRACT Livestock urine and dung are important components of the N cycle in pastures, but little information on its effect on soil nitrous oxide (N2O) emissions is available. We conducted a short-term (39-day) trial to quantify the direct N2O-N emissions from sheep excreta on an experimental area of ryegrass pasture growing on a Typic Paleudult in southern Brazil. Four rates of urine-N (161, 242, 323, and 403 kg ha-1 N) and one of dung-N (13 kg ha-1 N) were applied, as well as a control plot receiving no excreta. The N2O-N emission factor (EF = % of added N released as N2O-N) for urine and dung was calculated, taking into account the N2O fluxes in the field, over a period of 39 days. The EF value of the urine and dung was used to estimate the emissions of N2O-N over a 90-day period of pasture in the winter under two grazing intensities (2.5 or 5.0 times the herbage intake potential of grazing lambs). The soil N2O-N fluxes ranged from 4 to 353 µg m-2h-1. The highest N2O-N fluxes occurred 16 days after application of urine and dung, when the highest soil nitrate content was also recorded and the water-filled pore space exceeded 60 %. The mean EF for urine was 0.25 % of applied N, much higher than that for dung (0.06 %). We found that N2O-N emissions for the 90-day winter pasture period were 0.54 kg ha-1 for low grazing intensity and 0.62 kg ha-1 for moderate grazing intensity. Comparison of the two forms of excreta show that urine was the main contributor to N2O-N emissions (mean of 36 %), whereas dung was responsible for less than 0.1 % of total soil N2O-N emissions.

BRACHIARIA IN SELENIUM-CONTAMINATED SOIL UNDER SULPHUR SOURCE APPLICATIONS

ABSTRACT High contents of plant-available selenium in the soil in the form of selenate, resulting from natural or anthropogenic action, jeopardizes agricultural areas and requires research for solutions to establish or re-establish agricultural or livestock operation, avoiding the risk of poisoning of plants, animals and humans. The purpose was to evaluate sulfur sources in the form of sulfate, e.g., ammonium sulfate, calcium sulfate, ferric sulfate, in the remediation of tropical soils anthropogenically contaminated with Se under the tropical forage grass Brachiaria brizantha (Hochst. ex A. Rich.) Stapf cv. Marandu. More clayey soils are less able to supply plants with Se, which influences the effects of S sources, but it was found that high soil Se concentrations negatively affected forage biomass production, regardless of the soil. Of the tested S sources, the highly soluble ammonium sulfate and ferric sulfate reduced plant Se uptake and raised the available sulfur content in the soil.

The effect of cover crop and crop rotation on soil water storage and on sorghum yield

Crop rotation and cover crop can be important means for enhancing crop yield in rainfed areas such as the lower Coastal Bend Region of Texas, USA. A trial was conducted in 1995 as part of a long-term cropping experiment (7 years) to investigate the effect of oat (Avena sativa L.) cover and rotation on soil water storage and yield of sorghum (Sorghum bicolor L.). The trial design was a RCB in a split-plot arrangement with four replicates. Rotation sequences were the main plots and oat cover crop the subplots. Cover crop reduced sorghum grain yield. This effect was attributed to a reduced concentration of available soil N and less soil water storage under this treatment. By delaying cover termination, the residue with a high C/N acted as an N sink through competition and/or immobilization instead of an N source to sorghum plants. Crop rotation had a significantly positive effect on sorghum yield and this effect was attributed to a significantly larger amount of N concentration under these rotation sequences.

Endosperm genotyping as a strategy to differentiate the allele source in maize heterozygous progeny

The objective of this work was to distinguish the parental source of alleles in heterozygous progeny using semiquantitative polymerase chain reaction (PCR) in maize endosperm. Endosperms derived from direct and reciprocal single-cross hybrids between maize inbred lines L3 and L1113-01 were genotyped by semiquantitative PCR methodology (SQ-PCR) using fluorescent microsatellite primers. The amplification products were evaluated by the ratios of fluorescence intensity (RFI), calculated between the peaks corresponding to the alleles derived from each parental line. Based on the statistically significant contrast between RFI mean values of direct and reciprocal single-cross hybrids, it was possible to distinguish the number of alleles received from each parental line and, ultimately, to determine the origin of the alleles of each cross. Thus, endosperm genotyping using SQ-PCR is a promising strategy to map QTL in maize outbred populations.

Secondary metabolismin in Annonaceae: potencial source of drugs

Several species of Annona (Annonaceae) are used in traditional Mexican medicine by their anti-anxiety, anticonvulsant and tranquilizing properties. It has been reported that the alkaloids isolated from some species of the Annona have affinity to serotonergic 5-HT1A receptors and modulate dopaminergic transmission, which is involved in depressive disorders. In this review it is showed the results of the antidepressant-like effect of an alkaloid extract from the aerial parts of Annona cherimola (TA) in mice. The antidepressant-like effect was evaluated in the forced swimming test. To elucidate a possible mechanism of action, experiments of synergism with antidepressant drugs, such as imipramine (IMI), clomipramine (CLIMI), and fluoxetine (FLX), were carried out. The neurotransmitter content (DA: dopamine, 5HT: serotonin and its metabolites, HVA: homovanillic acid and 5HIAA:5-hydroxyindoleacetic) in the whole brain of mice were also determined by HPLC method. The results showed that repeated treatment with TA produced antidepressant-like effects in mice. This effect was not related to an increase in locomotor activity. Administration of TA facilitated the antidepressant effect of IMI and CLIMI as well as increased the turnover of DA and 5-HT. The alkaloids: 1,2-dimethoxy-5, 6.6 to 7-tetrahydro-4H-dibenzoquinoline-3,8,9,10-tetraol, anonaine, liriodenine, and nornuciferine were the main constituents of TA.

Ultrasound scan as a potential source of nosocomial and cross-infection: a literature review

AbstractThe authors review the main concepts regarding the importance of cleaning/disinfection of ultrasonography probes, aiming a better comprehension by practitioners and thus enabling strategies to establish a safe practice without compromising the quality of the examination and the operator productivity. In the context of biosafety, it is imperative to assume that contact with blood or body fluids represents a potential source of infection. Thus, in order to implement cleaning/disinfection practice, it is necessary to understand the principles of infection control, to consider the cost/benefit ratio of the measures to be implemented, and most importantly, to comprehend that such measures will not only benefit the health professional and the patient, but the society as a whole.

Distribuição de mercúrio em diferentes solos da Bacia do médio Rio Negro-AM: influência da matéria orgânica no ciclo biogeoquímico do mercúrio

Soils play an important role in the biogeochemical cycle of mercury as a sink for and source of this metallic species to atmospheric and hydrological compartments. In the study reported here, various types of soil were evaluated to ascertain the influence of parameters such as pH, organic matter content, Fe, Al, sand, silt, clay, C/H, C/N, C/O atomic ratios, and cation exchange capacity on the distribution of Hg in Amazonia's mid-Negro River basin. The data obtained were interpreted by multivariate exploratory analyses (hierarchical cluster analysis and principal component analysis), which indicated that organic matter plays an important role in mercury uptake in the various soils studied. The soils in floodable areas were found to contain 1.5 to 2.8-fold higher Hg concentrations than those in non-floodable areas. Since these soils are flooded almost year-round, they are less available to participate in redox processes at the soil/atmosphere interface. Hence, floodable areas, which comprise humic-rich soils, accumulate more mercury than non-floodable soils, thus playing an important role in the biogeochemical cycle of Hg in Amazonia's mid-Negro River basin.

Carotenoids production: microorganisms as source of natural dyes

Carotenoids are natural dyes synthesized by plants, algae and microorganisms. Application in many sectors can be found, as food dyeing and supplementation, pharmaceuticals, cosmetics and animal feed. Recent investigations have shown their ability to reduce the risks for many degenerative diseases like cancer, heart diseases, cataract and macular degeneration. An advantage of microbial carotenoids is the fact that the cultivation in controlled conditions is not dependent of climate, season or soil composition. In this review the advances in bio-production of carotenoids are presented, discussing the main factors that influence the microbial production of these dyes in different systems.

Chemical composition, circadian rhythm and antibacterial activity of essential oils of piper divaricatum: a new source of safrole

The essential oils from leaves, stems and fruits of Piper divaricatum were analyzed by GC-MS. The tissues showed high safrole content: leaves (98%), fruits (87%) and stems (83%), with yields of 2.0, 4.8 and 1.7%, respectively. This is a new alternative source of safrole, a compound widely used as a flavoring agent and insecticide. The leaf's oil showed antibacterial activity against gram-negative bacteria while safrole was active against Salmonella Typhimurium and Pseudomonas aeruginosa. In addition, the study of circadian rhythm of the safrole concentration in the essential oils of leaves showed a negligible variation of 92 to 98%.

Tropical biodiversity: has it been a potential source of secondary metabolites useful for medicinal chemistry?

The use of natural products has definitely been the most successful strategy in the discovery of novel medicines. Secondary metabolites from terrestrial and marine organisms have found considerable use in the treatment of numerous diseases and have been considered lead molecules both in their natural form and as templates for medicinal chemistry. This paper seeks to show the great value of secondary metabolites and emphasize the rich chemical diversity of Brazilian biodiversity. This natural chemical library remains understudied, but can be a useful source of new secondary metabolites with potential application as templates for drug discovery.

QSAR modeling: um novo pacote computacional open source para gerar e validar modelos QSAR

QSAR modeling is a novel computer program developed to generate and validate QSAR or QSPR (quantitative structure- activity or property relationships) models. With QSAR modeling, users can build partial least squares (PLS) regression models, perform variable selection with the ordered predictors selection (OPS) algorithm, and validate models by using y-randomization and leave-N-out cross validation. An additional new feature is outlier detection carried out by simultaneous comparison of sample leverage with the respective Studentized residuals. The program was developed using Java version 6, and runs on any operating system that supports Java Runtime Environment version 6. The use of the program is illustrated. This program is available for download at lqta.iqm.unicamp.br.