Variabilidade espacial das propriedades físicas e químicas do solo em áreas intensamente cultivadas

The spatial variability of physical and chemical properties of soil were evaluated to provide subsidies for management of the agricultural input. The chemical variables: P, organic matter (OM), K, Ca, Mg, pH, CEC and base saturation (BS); and physical variables: sand and clay were analysed. Soil samples were collected at two depths (0-0.2 and 0.6-0.8 m) located at irregular mesh of sampling in the region of Monte Alto, in a Yellow-Red Podzol (Alfissolo) (PVA), under different managements, resulting in 88 points in 1465 ha of total area; and at the region of Jaboticabal in a Red Latosol (LV) cultivated with sugarcane, resulting in 128 points in 2597 ha of total area. The chemical and physical soil properties studied showed spatial dependence, except CEC in 0.6-0.8 m layer for LV; Ca and clay at 0-0.2 m layer and P, OM, K, Mg, sand and clay in 0.6-0.8 m layer for PVA. The chemical and physical variables studied were adjusted to spherical and exponential models and some of them showed semivariogram without defined structure. The PVA showed low spatial continuity of chemical and physical properties, mainly in 0.6-0.8 m layer, which suffers less antropic influence. The LV soil showed more homogenous zones of fertility and granulometric composition.

Variabilidade espacial de perdas de solo, do potencial natural e risco de erosão em áreas intensamente cultivadas

The objective of this work was to identify the spatial variability of the natural erosion potential, soil loss and erosion risk in two intensely cultivated areas, in order to assess the erosion occurrence patterns. The soil of the area located at Monte Alto, São Paulo state, was classified as Paleudalf (PVA) with moderately slope, with different managements. The soil of the area located at Jaboticabal, São Paulo state, was classified as Haplortox(LV) with gentle slope and cultivated with sugarcane. A irregular grid was imposed on the experimental areas. Soil samples were obtained from 0-0.2 m depth at each grid point: 88 samples in Monte Alto area (1465 ha) and 128 samples at Jaboticabal area (2597 ha). In order to obtain the values of the studied variables USLE was applied at each grid point. Descriptive statistics were calculated, and geoestatistical analyses were performed for defining semivariograms. Kriging techniques to develop map showing spatial patterns in variability of selected soil attributes were used. All variables showed spatial dependence. The PVA soil showed higher erosion risk due to the slope and atual management compared to the soil LV.

Avaliação de fatores de risco de cães sororreagentes à leptospira spp. e sua distribuição espacial, em área territorial urbana

We aimed to evaluate the risk factor of serum reactive dogs to antileptospire agglutinin and their spatial distribution in an urban area. We collected 1,000 blood samples from dogs at 20 immunization centers, homogeneously distributed in the urban area (32 km²) of Botucatu, Sao Paulo, Brazil. Diagnosis was made by microscopic serum agglutination using 24 serovars of Leptospira spp. Statistical analysis was performed by Goodman's test with 5% of significance. Spatial clusters were tested by spatial scan statistic using SaTScan. We found that 17.9% dogs reacted to Leptospira spp. (p<0.0001). Dogs with street access (22.14%) were more reactive (p<0.05) than those without (14.83%). The scan test indicated only one significant cluster influenced by age. Incorporating each one of the co-variables gender, breed, and street access to age, we found that street access was the most important. Street access and age were the most important risk factors in the large number of reactive animals in the cluster, with the castellonis serovar being the most reactive in urban dogs. The identification of a cluster with more reactive dogs than expected allows local preventive measures to be taken.

Correlação espacial entre a altitude e as precipitaç ões pluviométricas no estado de São Paulo

The rain occurrence is one of the most important phenomena to determinate the climate and, as most of the other climatic phenomena, shows a continuous spatial variability that can be detected through special geostatistical methods. Besides the great influence of the topographic relief on the specific climate of each region, it is normal to expect spatial correlations of this variable with the precipitations; the determinism of this correlation may help to elaborate more precise conclusions involving these phenomena. In this paper, the spatial variability of altitude and of the pluviometric precipitations was rigorously analyzed, besides the existing correlation between these variables. It was concluded that these variables show strong spatial dependence and they are directly correlated. The mapping of the occurrence of both the phenomena was done by geostatistical methods pased on the infomiation concerning the spatial variability of each one.

Arranjo espacial de plantas de milho em sistema plantio direto

The interaction of management practices that increases plant density and reduces row spacing by spatial arrangement, if well planned, can be an excellent opportunity for the producers to increase their profitability. The objective of this study was to evaluate the variation effects of plant spatial distribution in two maize hybrids cultivated in a no-tillage system on the production components. The study was conducted in the CECA/UFAL. The treatments consisted of the cultivation of two hybrids of maize, FORT and AGN 30A00, in row spacings of 0.80 and 0.40 m and with plant densities of 60,000 and 70,000 plants ha -1. The statistical design was randomized blocks in a 2 x 2 x 2 factorial scheme, with three replications. From the results obtained, it may be concluded that neither the row spacing reduction nor plant density increase, as isolated practices, do not increase grain yield in the tested cultivars. The association of the reduction in row spacing and increase in plant population resulted in significant gain in grain productivity for the hybrid FORT.

Geoprocessamento aplicado na distribuição espacial da capacidade de uso de uma microbacia

The present study aimed to show the spatial distribution of the Rochas watershed (Avaré-SP, Brazil) soil use capacity using the Idrisi geographical information system in order to contribute to a better territorial organization and the planning of the appropriate soil occupation. The obtained results using this methodology showed that most of the Rocha watershed areas are from the following groups: dystrophic yellow-red latosol (36.64%), eutroferric and distroferric red latosol (30.30%) with sandy texture. There was a predominance of areas with slope classes of 0-12%, plain to wavy relief (61.37% of the watershed area) showing that these areas are appropriate for annual culture plantations with wide use of machinery. Most of these areas were classified as class IV (73.79%) as to use capacity. In the studied area the following subclasses of land use capacity were found: IIe, s; IIIe; IVe; IVs; IVe,s; VIe and VIIe. Capacity subclasses IVe; IVe,s; IVs and Vie were the most significant because they are areas that can be used for agriculture but subject to severe soil impoverishment if there are no special care mainly for annual cultures. The Idrisi geographical information system was efficient to determine soil use capacity of the Rocha's watershed showing that the use of geoprocessing tools makes data analysis easier and faster, allowing digital data storage for future analysis uses mainly for territorial planning and environmental studies.

¿Mejora la visualización espacial con el aprendizaje del dibujo técnico?

The present study article whether instruction in technical drawing improves aptitude for spatial visualization. Tests for visualization were administered to a sample of first year engineering students at the beginning and end of a technical drawing course. Findings show improvements in the visualization test performance in a moderate number of students; this effect was the same in both men and women. These results show that spatial visualization is an aptitude that can be enhanced with training.

Influência das superfícies geomórficas na distribuição espacial dos atributos do solo em área sob cultivo de cana-de-açúcar

Variations in soil attributes occur based on relief forms and parent material. The objective of this research was to study the influences of geomorphic surfaces on the spatial distribution of soil attributes in a sugarcane cultivation area. First, 530,67 hectares were mapped by using a Global Positioning System. Then, a Digital Elevation Model was developed and geomorphic surfaces were identified and delimited, according to topographic and stratigraphic criteria based on detailed field investigations. Soil samples were collected every 7 ha, at 0.0-0.25 m and 0.80-1.00 m depths, totalizing 134 samples. Texture, Ca, K, Mg, SB, CEC, V%, pH, and OMS analyses were carried out as well as descriptive statistics and geostatistics analysis. It was concluded that the geostatistic techniques and digital elevation model helped to notice that soil attributes presented limits close to the geomorphic surfaces ones.

Análise espacial de nutrientes e produção de alface cultivada em ambiente protegido

The objective of this work was to study spatial variability of some chemical soil attributes and lettuce production (total shoot fresh matter mass - MF; commercial shoot fresh matter mass - MFC; commercial shoot dry matter mass - MCS; and head commercial diameter - DCC) offering subsidies to the protected environment mapping in nutrients management areas in lettuce culture aiming for a higher productivity with application of fertilizers. The experiment was conducted in a protective environment (greenhouse) with lettuce irrigated by drip irrigation and sampling grid with 152 points. The special dependence analysis, determined by the variogram, was obtained with the aid of the GS+ Program. Considering the need for crop nutrients through the map obtained for element P (phosphorus) it was possible to establish two distinct areas for the application of this element in plantation fertilization. Through the lettuce yield maps obtained with MFC and DCC attributes was difficult to establish distinct areas for its management with data observed in only one crop cycle. Krigagem has proved useful for mapping the attributes studied.

Variabilidade espacial do estado nutricional do cafeeiro canephora visando o manejo localizado

Mapping the plant nutritional condition allows viewing different regions in a cropping area, providing the producers with different criteria to use foliar and soil fertilization. The aim of this study was to evaluate the spatial variability of the nutritional condition of canephora coffee (Coffea canephora Pierre ex Froehner) regarding the site specific management of foliar and soil fertilization. In a one hectare area 60 georeferenced points were sampled at irregular intervals. There were five plants in each sampled point; two pairs of leaves were removed from the lateral branches (3 rd and 4 th pairs from extremity to the basis) in the cardinal points of each plant, counting up 40 leaves per point. The foliar samples were chemically analyzed for the following nutrients: N, P, K, Ca, Mg, S, B, Cu and Zn. The same pattern of spatial dependence was presented with adjustment for K and B. Except for N and P, which presented random distribution, the other nutrients presented mild to severe spatial dependence justifying the geostatistical data analysis for making maps for differential and located, foliar and soil fertilizer application in coffee crop.

Variabilidade espacial de atributos químicos do solo cultivado com café arábica (Coffea arabica L.) sob diferentes manejos

The objective of this work was to assess the spatial variability of the chemical attributes of two coffee areas, managed in conventional and organic crop systems, and to calculate the percent of variation between them. In each area, a 40-point-mesh was sampled at 0-0.10 m and 0.10-0.20 m layers, within the crown projection, for pH, SB, K, P, Ca and Mg analysis. The data were analyzed through descriptive statistics and geostatistics. From the soil chemical attributes map, the percent of variation between the systems' chemical attributes was determined by GIS algebraic operations. The results show that the soil chemical attributes present a spatial dependence in both systems and layers. Analysis of the soil chemical attributes showed less spatial variability in the organic system, in relation to the conventional, indicating homogeneous zones for different fertilizer applications. The percent of variation of the chemical attributes in the conventional system, in relation to the organic, at 0-0.10 m and 0.10-0.20m layers are 54.80% and 35.61%, respectively.

Correlação linear e espacial entre a produtividade e o teor de proteína bruta do guandu anão e os atributos de um Latossolo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modelo agrometeorológico na estimativa da produtividade de duas variedades de café arábica considerando a variabilidade espacial

The purpose of this study was to estimate the varieties of coffee Arabic Catucáand Catuaí productivity, in Zona da Mata, Minas Gerais, through agrometeorological mathematical models, considering the spatial variability of productivity in the area. The samplings were georrefered building an irregular grid, totalizing 50 samplings per area. After that, geostatic analysis was made to quantify spatial dependence degree of the real values and the estimated productivity. According to the classification, the models superestimated the productivity for the two varieties.

Variabilidade espacial na produção da alface em ambiente protegido

Este artigo mostra a dinâmica da água após ser aplicada sobre a superfície de um solo cultivado com alface, num sistema fechado de um ambiente protegido. A aplicação de água se deu por meio de um sistema de irrigação por gotejamento, com o CUD ( Coeficiente de Uniformidade de Distribuição ) igual a 97,06 %, o que garantiu uma ótima uniformidade de distribuição, desconsiderando como possíveis causas das variações de umidade do solo, a aplicação de lâminas variadas. Fazendo uso de técnicas de geoestatística, interpolando sessenta pontos amostrais de evaporação, umidade do solo e produtividade da alface, com as mesmas sessenta coordenadas para os três atributos, verificou-se que a umidade do solo, mesmo momentos após a irrigação, não permanece uniforme ao longo do sistema de irrigação, constatando-se que a evaporação local exerce influência de forma predominante sobre a dinâmica da água na superfície do solo. Concluiu-se que as regiões no interior da estufa de maiores evaporações, foram as de maiores variações de umidade do solo e na produção de massa verde da alface.

Correlação espacial do índice de vegetação (NDVI) de imagem Landsat/ETM+ com atributos do solo

The precision agriculture technologies such as the spatial variability of soil attributes have been widely studied mostly with sugarcane. Among these technologies have been recently highlighted the use of the vegetation index derived from remote sensing products, such as powerful tools indicating the development of vegetation. This study aimed to analyze the spatial variability of clay content, pH and phosphorus in an Oxisol in an area with sugarcane production, and correlate with the Normalized Difference Vegetation Index (NDVI). The georeferenced grid was created for the soil properties (clay, phosphorus and pH) and generated the maps of spatial variability. For these same sites were calculated the NDVI, in addition to mapping of this ratio, the evaluation of the spatial correlation between this and other studied properties. The clay and phosphorus content showed positive spatial correlation with the NDVI, while no spatial correlation was observed between NDVI and pH. The satellite images from the sensor ETM + Landsat were used to correlate to NDVI to observe the spatial variability of the studied attributes.