The use of scaled semivariograms to plan soil sampling in sugarcane fields

Spatial sampling designs used to characterize the spatial variability of soil attributes are crucial for science studies. Sample planning for the interpolation of a regionalized variable may use several criteria, which could be best selected from an estimated semivariogram from a previously established grid. The objective of this study was to optimize the procedure for scaled semivariogram use to plan soil sampling in sugarcane fields in the Alfisol and Oxisol regions of Jaboticabal Town in So Paulo State, Brazil. A scaled semivariogram for several soil chemical attributes was estimated from the data obtained from two grids positioned on a sugarcane field area, sampled at a depth of 0.0-0.5 m. The research showed that regular grids with uniform intervals did not express the real spatial variability of the soil attributes of Oxisols and Alfisols in the study area. The calculated final sampling density based on the scaled parameters of the semivariogram was one sample for each 2 ha in Area 1 (convex landscape) and one sample for each 1 ha in Area 2 (linear landscape), as indicated by SANOS 0.1 software. The combined use of the simulation programs and scaled semivariograms can be used to define sampling points. These results may help in soil fertility mapping and thereby improve nutrient management in sugarcane crops.

Como desenhar e escrever um protocolo de pesquisa clínica em Cosmiatria

Cosmetic Dermatology is a growing subspecialty. High-quality basic science studies have been published; however, few double-blind, randomized controlled clinical trials, which are the major instrument for evidence-based medicine, have been conducted in this area. Clinical research is essential for the discovery of new knowledge, improvement of scientific basis, resolution of challenges, and good clinical practice. Some basic principles for a successful researcher include interest, availability, persistence, and honesty. It is essential to learn how to write a protocol research and to know the international and national regulatory rules. A complete clinical trial protocol should include question, background, objectives, methodology (design, variable description, sample size, randomization, inclusion and exclusion criteria, intervention, efficacy and safety measures, and statistical analysis), consent form, clinical research form, and references. Institutional ethical review board approval and financial support disclosure are necessary. Publication of positive or negative results should be an authors' commitment. © 2013 by Anais Brasileiros de Dermatologia.

Contribuições formativas do laboratório didático de física sob o enfoque das racionalidades

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A Educação física na escola e suas interfaces com os conteúdos de história e ciências nos livros didáticos

Pós-graduação em Ciências da Motricidade - IBRC

Optimization of the sampling scheme for maps of physical and chemical properties estimated by kriging

The sampling scheme is essential in the investigation of the spatial variability of soil properties in Soil Science studies. The high costs of sampling schemes optimized with additional sampling points for each physical and chemical soil property, prevent their use in precision agriculture. The purpose of this study was to obtain an optimal sampling scheme for physical and chemical property sets and investigate its effect on the quality of soil sampling. Soil was sampled on a 42-ha area, with 206 geo-referenced points arranged in a regular grid spaced 50 m from each other, in a depth range of 0.00-0.20 m. In order to obtain an optimal sampling scheme for every physical and chemical property, a sample grid, a medium-scale variogram and the extended Spatial Simulated Annealing (SSA) method were used to minimize kriging variance. The optimization procedure was validated by constructing maps of relative improvement comparing the sample configuration before and after the process. A greater concentration of recommended points in specific areas (NW-SE direction) was observed, which also reflects a greater estimate variance at these locations. The addition of optimal samples, for specific regions, increased the accuracy up to 2 % for chemical and 1 % for physical properties. The use of a sample grid and medium-scale variogram, as previous information for the conception of additional sampling schemes, was very promising to determine the locations of these additional points for all physical and chemical soil properties, enhancing the accuracy of kriging estimates of the physical-chemical properties.

Produção científica em organização do conhecimento: uma análise de domínio via cocitações de autores

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)