Spatial variability of soil physical attributes in Machadinho d Oeste (Ro), Amazon Basin.

The aim of this paper was to understand the spatial variability of soil physical attributes within the superficial layer (0-10 cm) in an area of agricultural colonization in Machadinho d?Oeste (RO). The attributes analyzed were real density, clay, silt, coarse sand, and fine sand contents. In September, 2004, 76 samples were collected through an irregular sampling strategy, based on soil and topographic features. Oxisols and Ultisols are the predominant soil types in the area. The clay content ranged from 2 to 67%, silt from 2 to 63%, coarse sand from 4 to 78%, fine sand from 6 to 45%, and real density from 2.08 to 2.60 (g cm-3). Some of the high contents of silt can be due to resistant aggregates of the clay fraction, as the adopted methodology did not separate clay grains. The majority of attributes presented coefficients of variation higher than 40%, except for real density. Real density is highly correlated with the coarse sand fraction (r = 0,94) and with the sum of the clay and silt fractions (r = -0,86). Geostatistics was used to understand the spatial variability of such attributes, through the analysis of semivariograms, kriging, and isoline maps. Despite statistical distances among the samples, the spatial dependence ratio (RD) was classified as moderate and strong. The spherical model had good adjustment for the studied attributes. Similarities were found for the spatial behavior of some attributes, such as clay, coarse sand, and real density. The lowest range values were for clay, silt, and coarse sand (i.e., around 10,000 m). For fine sand and real density, the range was between 15,000 and 16,000 m. Kriging techniques were suitable to depict the space distribution of the studied attributes. Soils with clay contents higher than 30% are predominant in the area, followed by soils with loam texture

Spatial variability of some biometric attributes of sugarcane plants (variety IACSP93-3046) and its relation to physical and chemical soil attributes.

Tests to evaluate competition between plants, in general do not consider the soil spatial variability, nevertheless, the uniformity rarely is present and can not be assumed without verification. The aim of this work was to apply geostatistics to verify the spatial variability of the soil in an experimental field near Ribeirão Preto, SP, with sugarcane variety IACSP93-3046. Ninety seven geo-referenced samples, placed at distances of 10 m, were collected for soil chemical analysis, soil resistance to penetration and biometric evaluation of the sugar cane plant included number of tillers, stalk diameter, stalk height, estimated productivity (TSSe) and root density. Geostatistics has been applied by means of semivariogram, data interpolation via kriging and iso-line maps creation. The results have shown soil spatial dependence for most of the evaluated attributes. The spots, within the area, with low resistance to penetration and low soil density have shown the largest number of tillers and the largest root development of sugar cane. For soil chemical attributes, there was spatial dependence showing higher concentration of nutrients in the central area. The sampling allowed a good representativity of the spatial dependence of soil and plants, making it possible to eliminate the randomness hypothesis for the placement of the plots in this area

Rapid bioassay for evaluating enzyme production in fungal isolates from environmental sources

Fungal hydrolytic enzymes have a great potential due to the rapid development of enzyme technology and their industrial applications. A fluorimetric microplate assay has been developed for measuring activity of β-D-exoglucanase, β-D-glucosidase, α-D-glucosidase, β-N-acetyl-hexosaminidase, β-D-xylosidase in diluted culture broth samples. The substrates used are conjugates of the highly fluorescent compounds 4-methylumbelliferone (MUB) and thus product formation can be measured directly in the microplate without previous extraction and purification of the product. The developed system was evaluated on eight fungal strains isolated from shrub species (Tamarix) that can be used in phytoremediation. Depending upon the enzyme, each species exhibited different levels of enzymatic activities as well as different production profiles. The fluorimetric method could constitute an effective alternative to the pectrophotometric method to screen hydrolase-producing microbial strains

Beef cattle stocking rate, a key to the conservation of the pastoral system in Brazilian biomes.

Abstract: In Brazil, beef cattle are raised in predominantly extensive systems. The feeding base is represented by native and/or cultivated pastures. The latter may be in a well conserved state or may present some degree of degradation. The amount of animals per hectare, supported by the pasture by each time unit, is basically related to the pasture production. There is interaction between quality and production, and changes in these parameters are strongly affected by the stocking rate. Therefore, the adjustment in the stocking rate is the most important management factor and the main determinant of animal production and pasture composition. Municipal data from the 2006 agriculture and cattle raising business census were considered with the objective to analyze, by means of typologies, the use of pastoral areas in Brazil. In the census, the producers declared their pastoral areas according to the following classification: native pasture areas (PN), cultivated pasture areas in good conservation status (PC) and cultivated pasture areas with some degree of degradation (PCD). They also indicated the number of bovine in each type of pasture. The data were submitted to exploratory factorial analysis, with varimax rotation. The first two factors (extracted by main components) explained 0.83 of the (co)variance, and the estimate of the Kaiser-Mayer-Olkin (KMO) adequacy test was 0.76, which meant good adjustment of the variables selected. The commonalities of the variables selected, PN area; total pasture area (TP), bovines in PN (Bov_PN); bovines in PCD area (Bov_PCD); bovines in PC area (Bov_PC); bovines in total pasture area (Bov_APT); and the stocking rate (TxLota) were 0.65; 0.97; 0.77; 0.74; 0.79; 0.87; and 0.99, respectively. The first factor was associated with the variables PN, TP, Bov_PN, Bov_PCD, Bov_PC, and Bov_APT, which directs to the latent variable correlated to those municipalities with large pasture areas, in general, and also with the largest cattle population. The variable TxLota presented the most significant factorial load in the second factor, that is, all those municipalities with the greatest concentration of cattle per unit area are represented in the second factor. The municipalities that were best represented in factor_1 are different from the ones represented in factor_2. The non-parametric correlation between the classifications of the two groups of municipalities formed by the factorial scores in the first and the second factors is small (0,24). This indicates that the context of those municipalities with the highest stocking rate is a lot different from the ones with the largest areas and cattle herds. The application of livestock development policies in the different Brazilian biomes should take into account all the distinguishing features of the municipalities, regarding their context, especially the pasture areas and their vocation for primary livestock production.ICAS VI

Densidade do solo de um Nitrossolo sob cultivo de cana-de-açúcar utilzando analises geoestatística e bayesiana.

O objetivo desse trabalho foi avaliar a variabilidade espacial da densidade do solo sob cana-de-açúcar, através da geoestatística e da análise bayesiana. Foi determinada a densidade do solo (g cm-3) em uma área de 17,8ha em Mogi Mirim, SP, nas profundidades de 0,15m e de 0,30m, em 90 pontos de amostragem. O padrão espacial foi encontrado tanto na profundidade de 0,15m quanto 0,3m. Os valores de densidade foram considerados altos e maior na maior profundidade. Tanto pelo método de análise geoestatística, quanto bayesiano houve padrão espacial com ligeiro aumento na escala de valores dos mapas de densidade para análise bayesiana

Variabilidade espacial do rendimento de culturas e dos atributos físicos de um latossolo vermelho sob semeadura direta.

O conhecimento da variabilidade espacial dos atributos físicos do solo relacionados com o seu estado de compactação favorece o manejo específico dos fatores de produção. Desta maneira, o objetivo deste trabalho foi avaliar a variabilidade espacial de atributos físicos do solo e da produtividade de distintas culturas em um Latossolo Vermelho sob semeadura direta em Campinas (SP). A área em estudo está localizada no Centro Experimental Central do Instituto Agronômico. A área de 3,42 ha vem sendo manejada desde 1985 com semeadura direta em rotação de culturas. Os atributos físicos do solo estudados foram: textura (g kg -1), densidade (kg dm3), porosidade total (m3 m-3) e resistência do solo à penetração (MPa). As culturas envolvidas neste estudo foram: labelabe (2002), milho (2003), triticale (2004) e mamona (2005). Os resultados indicam que a área de estudo não apresenta problemas de compactação. A parte lateral esquerda da área apresentou os maiores valores de produtividade e os menores valores de densidade e os maiores valores de porosidade total

Espacialização e correlação entre os nutrientes do solo de Machadinho D' Oeste, RO.

Tanto o planejamento quanto a sustentabilidade agrícola de projetos de assentamento rural, como o de Machadinho d' Oeste, podem ser beneficiados com informações espaciais da fertilidade do solo. O objeto do trabalho foi identificar a dependência espacial dos macro e micronutrientes do solo de Machadinho d"Oeste, RO, e a existência de correlação entre eles. Foram utilizados 76 pontos de amostragem e determinados os macros e micronutrientes a uma profundidade de 0-10 cm. Para analisar a variabilidade espacial, usou-se a geoestatística, por meio da análise de semivariogramas, interpolação dos dados por "krigagem" e construção de mapas de isolinhas. Para identificar a correlação entre duas variáveis foram construídos e ajustados os "cross" semivariogramas. Os resultados indicam baixo nível de fertilidade devido ao baixo teor de bases e a presença de alumínio e hidrogênio. Houve correlação espacial positiva significativa entre soma de bases com cálcio e magnésio, entre alumínio e hidrogênio e entre pH CaCl2 e pH em água. Já entre alumínio e PH CaCl2 ocorreu correlação negativa e não houve correlação significativa entre os micronutrientes, decorrentes as pequenas manchas com valores máximos discrepantes. A espacialização decorrente da correlação espacial existente evidenciou a baixa fertilidade na maior parte da área de Machadinho d"Oeste, RO

Variabilidade espacial da infiltração de água em solo sob pastagem em função da intensidade de pisoteio.

O objetivo deste trabalho foi avaliar o efeito da intensidade de pisoteio do gado na variabilidade espacial da infiltração de água no solo. O experimento foi conduzido em um Argissolo Vermelho?Amarelo, com pastagem de Urochloa brizantha dividida em seis piquetes de 1 ha, cada um com 50 pontos de amostragem, em grade de 10x10 m. Em cada local de amostragem, foi medida a taxa de infiltração tridimensional de água em solo saturado, nas profundidades de 0,10 e 0,20 m. As medições foram realizadas na primeira, décima primeira e décima quinta passagens do gado pelos piquetes. Os dados obtidos foram submetidos à análise geoestatística, para avaliação da variabilidade espacial das propriedades do solo. As 15 passagens do gado pelos piquetes resultaram em diminuição da taxa de infiltração de água no solo de 73,3% a 0,10 m e de 64,6% a 0,20 m de profundidade. O estudo da variabilidade espacial da taxa de infiltração de água no solo, por meio da geoestatística, possibilita a construção de mapas para a avaliação dos efeitos da intensificação do pisoteio do gado sobre as propriedades físicas do solo. A taxa de infiltração de água no solo apresenta estrutura de dependência espacial que aumenta em função da intensidade do pisoteio do gado

Limits on Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array

We have used the Berkeley-Illinois-Maryland-Association (BIMA) millimeter array outfitted with sensitive cm-wave receivers to search for Cosmic Microwave Background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration which produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is 6.6 arcminutes. We have made sensitive images of seven fields, five of which where chosen specifically to have low IR dust contrast and be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power Q_flat = 5.6 (+3.0 -5.6) uK and Q_flat < 14.1 uK at 68% and 95% confidence. The sensitivity of this experiment to flat band power peaks at a multipole of l = 5470, which corresponds to an angular scale of approximately 2 arcminutes. The most likely value of Q_flat is similar to the level of the expected secondary anisotropies.Comment: 15 pages, 5 figures, LaTex, aas2pp4.sty, ApJ submitte