Gabriel Araújo e Silva Ferraz

Geostatistical analysis of fruit yield and detachment force in coffee

The aim of this study was to use geostatistical analysis to evaluate the spatial variation in the detachment force of coffee fruit and coffee yield by variograms and kriging for precision agriculture. This study was conducted at Brejão farm, Três Pontas, Minas Gerais, Brazil. The detachment force of green and mature coffee fruit was measured with a prototype dynamometer and georeferenced. The yield data were obtained from manual harvesting and were georeferenced. The data were evaluated by variograms estimated by residual maximum likelihood (REML), which provided a satisfactory approach for modeling all the variables with a small sample size. Spherical and exponential models were fitted, the first provided the better fit to mature fruit detachment force and the latter provided the better fit to coffee yield and green fruit detachment force. They were used to describe the structure and magnitude of spatial variation in the variables studied. Kriged estimates were obtained with the best fitting variogram models and mapped. The statistical and geostatistical analyses enabled us to characterize the spatial variation of the detachment force of green and mature coffee fruit and coffee yield and to visualize the spatial relations among these variables. The precision agriculture techniques used in this paper to collect, map and analyze the variables studied will help coffee farmers to manage their fields. Maps of coffee yield will enable farmers to apply nutrients site-specifically and manage harvesting either manually or mechanically. In addition, maps of detachment force of coffee fruit can enable farmers to harvest coffee selectively by choosing the appropriate places and the right time to start. This will improve the quality of the final product and also increase profits.

Variabilidade espacial e temporal do fósforo, potássio e da produtividade de uma lavoura cafeeira

The Precision Agriculture appears as an important tool to the management of coffee farms where the knowledge of some soil features associated with the coffee production could help specific application of fertilizing with positive environmental and economic results. So the aim of this study was to use precision agriculture and geoestatistics to evaluate the variables phosphorus, potassium and the coffee plant yield, in three different crops, by evaluating the semivariogram and kriging maps and show that these tools are important to the coffee management. This study was conducted on the Brejao farm in Tres Pontas, Minas Gerais, in 2007/2008, 2008/2009 e 2009/2010 crop. As data base were used chemical soil data obtained by sampling in a georreferenced location using a quadricycle with a sampler and a GPS, and the yield data was obtained from manual harvest on the georreferenced location. It was possible to characterize the spatial variability magnitude of the studied attributes, and they presented huge variation on time and space. Adjusts of the best semivariograms enable to produce more accurate maps that contribute to the geostatistics uses on coffee crop.

Agricultura de precisão no estudo de atributos químicos do solo e da produtividade de lavoura cafeeira

Precision agriculture appears as an important tool in the management of coffee farms where the knowledge of some soil fertility characteristics associated with the coffee production could help in specific application of fertilizers with positive environmental and economic results. So the aim of this article was to use precision agriculture and geoestatistics to evaluate the availability of phosphorus, potassium and yield of the coffee plant by evaluating the semivariogram and kriging maps and show that these tools are important for coffee management. This study was conducted on the Brejão farm in Três Pontas, Minas Gerais state, Brazil. As a data base we used soil chemical property data obtained by sampling in a georreferenced location using a quadricycle with a sampler and a GPS, and the yield data was obtained from manual harvest on the georreferenced location. The analysis of these data by using statistics and geostatistics tools allowed to characterize the spatial variability of the phosphorus, potassium, and the coffee yield, and allowed to analyze the relation among these variables. It was possible to observe that spatial dependence exists so it is possible to create maps of spatial distribution of the variables.

Variabilidade espacial dos atributos da planta de uma lavoura cafeeira

Objetivou-se com esse trabalho caracterizar a estrutura e a magnitude da distribuicao espacial de atributos da planta em lavoura cafeeira e realizar o mapeamento desses atributos de forma a visualizar a distribuicao espacial, considerando a dependencia espacial destes atributos, demostrando a importância deste mapeamento. Este trabalho foi conduzido na fazenda Brejao no municipio de Tres Pontas, Minas Gerais, utilizando-se os seguintes atributos da planta: Produtividade, Indice de Maturacao, Enfolhamento, Forca de Desprendimento de Frutos Verde, Forca de Desprendimento de Frutos Maduros, Diferenca entre a Forca de Desprendimento de Frutos Verde e Maduros, Altura de Planta e Diâmetro de Copa amostrados em uma malha amostral de 100 pontos georreferenciados (64 pontos da malha base e 36 pontos de zoom). A analise destes dados por meio das tecnicas estatisticas e da geoestatistica possibilitaram caracterizar a variabilidade espacial dos atributos da planta em estudo, permitindo o mapeamento destas variaveis. Foi possivel observar a importância da cafeicultura de precisao no manejo de uma lavoura cafeeira tanto no gerenciamento da colheita quanto no acompanhamento do desenvolvimento da planta.

Variabilidade espacial da força de desprendimento de frutos do cafeeiro

O objetivo deste trabalho foi utilizar tecnicas de georreferenciamento e de geoestatistica para analisar a variabilidade espacial da forca de desprendimento de frutos de cafeeiros por meio de semivariogramas e pela interpolacao por krigagem. O trabalho foi conduzido no municipio de Tres Pontas - MG, Brasil. A forca de desprendimento dos frutos verdes e de cerejas dos cafeeiros foi obtida por meio de um prototipo de dinamometro em pontos georreferenciados. A dependencia espacial dos dados foi analisada por meio de ajustes de semivariogramas, classico e robusto, para o metodo dos minimos quadrados ordinarios e ponderados, e apenas o ajuste classico, para os metodos da maxima verossimilhanca e maxima verossimilhanca restrita. Testaram-se, para cada um dos metodos, os modelos esferico, exponencial e gaussiano. Os mapas de isolinhas obtidos por krigagem foram produzidos, baseados no melhor metodo e modelo de ajuste da funcao semivariograma, que foram obtidos pelas estatisticas de validacao. As variaveis em estudo apresentaram estruturas de dependencia espacial, as quais foram modeladas pelos semivariogramas, o que possibilitou a confeccao dos mapas de isolinhas de distribuicao espacial, obtidos por krigagem. Foi possivel identificar os locais mais propicios para se iniciar a colheita seletiva e mecanizada dos frutos do cafeeiro.

Análise da variabilidade espacial da força de desprendimento dos frutos do cafeeiro sob pivô central

Due to the importance of coffee to the economy of Brazil and the increase of areas even in zone with water deficits during the year, it is necessary to study the factors involved in its production, especially for mechanized and selective harvesting. At this stage coffee farmers find it difficult to determine the appropriate time to start. This research was carried out to evaluating the spatial variation of force detachment of the coffee fruits (green and cherry) under center pivot through geostatistical methods, semivariogram analysis and kriging interpolation, to improve management for harvest mechanical and selective coffee. The test was carried out at Farm Sao Joao Grande, in Presidente Olegario/MG, in a pivot 50.0 ha. The cultivar used was the “Catuai Vermelho IAC 144”, planted in a circular way in December 2000, spaced 4.0 x 0.5 m. The sampling grid was irregular with 100 points georeferenced where each point corresponds to 4 plants. The determination of force detachment was conducted using a digital dynamometer at each sampling point. Within the maturation stages, green fruits presented detachment force greater than the cherry. The semivariogram and kriging allowed to characterize the variability of force detachment between the studied fruits. The kriging maps make it possible to farmers the choice the best place and the right time to start harvest mechanized and selective coffee and consequently, improved final product quality and profits.Due to the importance of coffee to the economy of Brazil and the increase of areas even in zone with water deficits during the year, it is necessary to study the factors involved in its production, especially for mechanized and selective harvesting. At this stage coffee farmers find it difficult to determine the appropriate time to start. This research was carried out to evaluating the spatial variation of force detachment of the coffee fruits (green and cherry) under center pivot through geostatistical methods, semivariogram analysis and kriging interpolation, to improve management for harvest mechanical and selective coffee. The test was carried out at Farm Sao Joao Grande, in Presidente Olegario/MG, in a pivot 50.0 ha. The cultivar used was the “Catuai Vermelho IAC 144”, planted in a circular way in December 2000, spaced 4.0 x 0.5 m. The sampling grid was irregular with 100 points georeferenced where each point corresponds to 4 plants. The determination of force detachment was conducted using a digital dynamometer at each sampling point. Within the maturation stages, green fruits presented detachment force greater than the cherry. The semivariogram and kriging allowed to characterize the variability of force detachment between the studied fruits. The kriging maps make it possible to farmers the choice the best place and the right time to start harvest mechanized and selective coffee and consequently, improved final product quality and profits.

ANÁLISE ESPACIAL DO TEOR DE ARGILA E UMIDADE GRAVIMÉTRICA, EM DIFERENTES CAMADAS DE PROFUNDIDADE, EM UM LATOSSOLO VERMELHO DISTRÓFICO

Nos ultimos anos, muitos produtores rurais vem buscando adotar a agricultura de precisao para aumentar a eficiencia de seus sistemas produtivos, por meio da identificacao da variabilidade que afeta a produtividade das plantas. Um dos fatores limitantes ao crescimento e desenvolvimento de plantas e a umidade do solo, influenciada por varios fatores, dentre eles o teor de argila presente no solo. O presente trabalho teve como objetivo avaliar, por estatistica descritiva e geoestatistica, a variabilidade da umidade gravimetrica e do teor de argila de uma lavoura cafeeira em Tres Pontas - MG, em diferentes camadas de profundidade. Para todas as variaveis avaliadas, nao foi possivel identificar a variabilidade existente na lavoura apenas por meio da estatistica descritiva. Em relacao a geoestatistica, todas as variaveis apresentaram dependencia espacial forte, permitindo a criacao dos mapas tematicos. Comparando-se os mapas tematicos, observou-se que regioes que apresentam o menor teor de argila possuem menores valores de umidade gravimetrica.

Spatial Variability of Air Temperature In A Broiler House During The Heating Phase

The air temperature (tair) exerts great influence on the development of poultry during their heating phase. Therefore, the aim of this study was to analyze the structure and the magnitude of the tair spatial variability, using geostatistics tools such as semivariogram analysis and also producing kriging maps. The experiment was conducted in the west mesoregion of Minas Gerais State in 2010, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the first 14 days of the birds’ life. It was possible to characterize the variability of the tair, which allowed to observe the spatial dependence by using geostatistics techniques. In addition, the use of geostatistics and distribution maps made possible to identify problems in the heating system in regions inside the broiler house that may harm the development of chicks.