Multivariate analysis and geostatistics of the fertility of a humic rhodic hapludox under coffee cultivation

The spatial variability of soil and plant properties exerts great influence on the yeld of agricultural crops. This study analyzed the spatial variability of the fertility of a Humic Rhodic Hapludox with Arabic coffee, using principal component analysis, cluster analysis and geostatistics in combination. The experiment was carried out in an area under Coffea arabica L., variety Catucai 20/15 - 479. The soil was sampled at a depth 0.20 m, at 50 points of a sampling grid. The following chemical properties were determined: P, K+, Ca2+, Mg2+, Na+, S, Al3+, pH, H + Al, SB, t, T, V, m, OM, Na saturation index (SSI), remaining phosphorus (P-rem), and micronutrients (Zn, Fe, Mn, Cu and B). The data were analyzed with descriptive statistics, followed by principal component and cluster analyses. Geostatistics were used to check and quantify the degree of spatial dependence of properties, represented by principal components. The principal component analysis allowed a dimensional reduction of the problem, providing interpretable components, with little information loss. Despite the characteristic information loss of principal component analysis, the combination of this technique with geostatistical analysis was efficient for the quantification and determination of the structure of spatial dependence of soil fertility. In general, the availability of soil mineral nutrients was low and the levels of acidity and exchangeable Al were high

Variabilidade espacial de atributos químicos de um Latossolo Vermelho-Amarelo húmico cultivado com café Spatial variability of chemical attributes of an Oxisol under coffee cultivation

O objetivo do presente estudo foi analisar a variabilidade espacial de atributos químicos de um Latossolo Vermelho-Amarelo húmico. O estudo foi realizado em uma área cultivada com Coffea arabica L. variedade Catuaí. As amostras de solo foram coletadas na profundidade de 0-20 cm, distribuídas em uma malha amostral, com 50 pontos. Os atributos químicos estudados foram: P, Na e S disponíveis, Ca, Mg e Al trocáveis, pH, H + Al, SB, t, T, V, m, MO, ISNa, P-remanescente e micronutrientes (Zn, Fe, Mn, Cu e B). Os dados foram analisados por meio da análise da estatística descritiva, seguida de uma análise de componentes principais com posterior análise de agrupamento. A geoestatística foi utilizada para verificar a existência e quantificar o grau de dependência espacial dos componentes principais. O método de análise multivariada com base nos componentes principais forneceu componentes interpretáveis, sendo o primeiro relacionado com a acidez e o segundo com o teor de matéria orgânica do solo. As técnicas de análise multivariada, em associação com a geoestatística, facilitaram a avaliação da variabilidade do solo; os componentes principais 1 e 2 apresentaram dependência espacial moderada, com maior continuidade espacial observada para o componente 1, o que permitiu melhor caracterização da acidez do solo. O solo em estudo apresentou, ao longo da encosta, disponibilidade reduzida de nutrientes, considerável acidez, menores teores de matéria orgânica na porção central da área e valores elevados de Al trocável na porção superior desta.<br>The objective of this study was to analyze the spatial variability of chemical attributes of an Oxisol. The experiment was conducted with Coffea arabica L., variety Catuai, at a depth of 0-0.2 m in a grid area totaling 50 points. The studied chemical attributes were: P, K, Ca, Mg, Na, S, Al, pH, H + Al, SB, t, T, V, m, MO, ISNa, equilibrium P and micronutrients (Zn, Fe, Mn, Cu, and B). The data were analyzed by descriptive statistical analysis, followed by principal component with subsequent cluster analysis. The existence of spatial dependence was verified and the degree quantified using the principal components and geostatistics. The method of multivariate analysis based on principal components provided interpretable components; the first were correlated with acidity and the second with soil organic matter. Techniques of multivariate analysis, in combination with geostatistics, facilitated the evaluation of soil variability. The principal components 1 and 2 indicated moderate spatial dependence, with greater spatial continuity in component 1, which allowed a better characterization of soil acidity. Reduced availability of soil nutrients and considerable acidity were observed along the slope, lower levels of organic matter in the center of the area and high Al contents in the upper part

Alfa-amilase em frangos de corte: efeitos do balanço eletrolítico e do nível protéico da dieta Alpha-amylase in broiler chickens: effects of electrolytic balance and dietary protein level

Um experimento foi conduzido com pintos de corte macho para o estudo dos efeitos dos níveis de 20 e 23% de PB combinados com 0, 50, 100, 150, 200, 250 mEq/kg de balanço dietético eletrolítico (BDE) sobre a atividade da alfa-amilase pancreática de frangos de corte de 1 a 21 dias de idade. O delineamento utilizado foi o inteiramente casualizado. Dietas e água foram fornecidas ad libitum. Aos 1, 7, 14 e 21 dias, três aves de cada tratamento foram sacrificadas por deslocamento cervical para remoção do pâncreas, o qual foi removido, homogeneizado, congelado em nitrogênio líquido e liofilizado. Uma alíquota de cada amostra foi solubilizada em água deionizada e centrifugada a 7500 x g por 3 minutos a 4ºC, para determinação da atividade da alfa-amilase no sobrenadante. Aves alimentadas com 20% de PB apresentaram atividades específicas (U/mg de proteína) superiores à daquelas que receberam 23%, exceto para os níveis de BDE de 100 a 200 mEq/kg, aos 14 dias. Observou-se tendência de aumento da atividade específica dos 7 aos 14 dias e redução dos 14 aos 21 dias. Para maior atividade específica de alfa-amilase, recomendam-se dietas com 20% de PB e 200 mEq/kg de BDE na fase pré-inicial e dietas com 20% de PB e 135 a 250 mEq/kg de BDE para frangos de corte dos 8 aos 21 dias de idade.<br>An experiment was conducted with male broiler chicks to study the effects of 20 and 23% of crude protein (CP) combined with 0, 50, 100, 150, 200, 250 mEq/kg of dietary electrolytic balance (DEB) on the pancreatic alpha-amylase activity from 1 to 21 days. A completely randomized factorial design was used. Feed and water were supplied ad libitum. At days 1, 7, 14 and 21, three birds from each treatment were sacrificed by cervical dislocation, pancreas were removed, homogeneized and frozen in liquid nitrogen which were then freeze-dried. An aliquot of each sample was solubilized with deionized water and centrifuged at 7500 x g for three minutes at 4ºC. Activities of the pancreatic alpha-amylase in the supernatants were determined. Chicks fed 20% of CP showed specific activities (U/mg protein) higher than those fed 23%, except for DEB levels from 100 to 200 mEq/kg at 14 days. A tendency to increase specific activity was observed from 7 to 14 days and to reduce from 14 to 21 days. The highest specific activity of pancreatic alpha-amylase was observed in diets with 20% CP and 200 mEq/kg of DEB from 1 to 7 days, diets with 20% of CP and 135 to 250 mEq/kg of DEB from 8 to 21 days of age