Ziany Neiva Brandão

Variabilidade espacial da fertilidade do solo em área cultivada com algodoeiro no Cerrado do Brasil

The objective of this work was to analyze the spatial variability of fertility attributes in an Oxisol under tillage to cotton cultivation in Cristalina, GO, aiming the adoption of precision agriculture in the area management. The soil was collected using a sample grid, which consisted of 90 points (80 x 80 m), distributed into 57.6 ha. Were determined contents of P, K, Ca, Mg, S, Na, Cu, Mn, B, Zn, Fe, organic matter (OM), pH, sum of bases (SB), base saturation (V), aluminum saturation (m), as well as the apparent electrical conductivity of soil (EC) measured at 30 and 90 cm depth. Classic descriptive analysis was conducted and then, semivariograms were modeled for all attributes and krigging maps. The spatial dependence of analyzed soil properties indicates that the spatial variability should be considered during the planning of soil sampling and also to soil management practices. Concerning to precision agriculture adoption and the application of inputs in variable rates, it is required to do a careful study of the soil fertility variability, creating maps based on fertility classes for each attribute, allowing to identify for which attributes this management practice should be adopted.

Qualidade da semente e fibra de algodão na caracterização do descaroçador de 25 serras 1

A B S T R A C T The cotton is one of the most important crop in the fiber group due to its volume and valued production. This study was conducted with the aim to characterize a ginner regarding physical and physiological quality of seeds and some technological qualities of the cotton fiber. The ginner was made with the following components: cleaner, cylinder saws, cylinder brushes, condenser, and a three-phase electric motor of 3 CV to turn on the equipment. The experimental design was a completely randomized factorial (2 x 2 x 2 x 4), with two cotton cultivars (BRS 187 and BRS Safira 8H), two types of saws (11¾” and 12”), two cleaning process (with and without cleaner) and four rotations (500, 550, 600 and 650 rpm) and four replications. During the processing of seeds, types of saws and cleaning processes did not affect the physical and physiological quality of seeds. Meanwhile, in the technological characteristics of the cotton fiber, the ginner showed efficient performance with the rotation of 550 rpm, using the 12” saws and cleaning device turned activated (cleaner). Palavras-chave: beneficiamento qualidade de sementes qualidade de fibras

Evapotranspiração real obtida através da relação entre o coeficiente dual de cultura da FAO-56 e o NDVI

REAL ACTUAL EVAPOTRANSPIRATION OBTAINED THROUGH THE RELATIONSHIP BETWEEN THE FAO-56 CROP DUAL COEFFICIENT AND NDVI A fundamental requirement for adoption of irrigation management is to determine the crop daily evapotranspiration (ET). On an operational basis the crop coefficient method proposed by the Food and Agriculture Organization (FAO) through its report 56 (Irrigation and Drainage Paper) is widely used in the determination of ET and due to its accurate estimative, it has been globally accepted. The ET-based crop coefficient (Kc) obtained from vegetation indices, particularly the Vegetation Index Normalized Difference (NDVI) has been measured in several studies and various crops showing great accuracy when compared to field observations. The objective of this study was to calculate the daily and seasonal ET of cotton crop using the method of dual Kc obtained as a function of the NDVI obtained from TM - Landsat 5 images clouds free. The obtained results are reliable, because less than 10% differences were found when comparing to the Bowen ratio technique observations, corroborating to the method performance achieved in other experiments conducted in other regions

Spectral reflectance of satellite images using geostatistics methods to estimate growth and cotton yield

The objective of this study was the spatial identification of the NDVI index and cotton yield distributions through different crop phenological stages using geostatistical methods in Goiás state, Brazil. The experiment was carried out in a commercial field with 47.4 ha, in 80x80m georeferenced grid with 74 plots. Yield monitor data and multispectral satellite images at 56 m spatial resolution were collected in a rainfed cotton field in two dates to monitor the plant vigor. Satellite images of AWiFS sensor were acquired on 08/02/2011 and 01/04/2011, during the first flowering and fruiting cotton stages, respectively, corresponding to 70 and 120DAE (days after emergence). Measures of canopy reflectance, plant height and leaf nitrogen content were determined and cotton yield was obtained by mechanical harvest in August, 2011. Data were analyzed using descriptive statistics, correlation and geostatistical analyses by building and setting semivariograms and kriging interpolation. Best correlation was found between NDVI and cotton yield at 120DAE. At first flowering, the NDVI and cotton yield showed strong spatial dependence, while for 120DAE there was no dependence, probably due to the enlargement of vegetated coverage. There were similarities in the bottom left of the study area with high values of NDVI, as well as the highest values of cotton yield due to excellent plant vigor in the cotton flowering stage. Identifications of spatial differences were possible using geostatistical methods with remote sensing data obtained from medium resolution satellite images, allowing to identify distinct stages of plant growth and also to predict the cotton yield.

Insights and recommendations of use of UAV platforms in precision agriculture in Brazil

The Interest in Unmanned Aerial Vehicles (UAVs) has grown around the world and several efforts are underway to integrate UAV operations routinely and safely into remote sensing applications, specially applied in precision agriculture. Reviewing the use of UAV in agriculture it shows limitations and opportunities. So the challenges of UAV platforms for remote sensing and precision agriculture were identified during a real case studied at a citrus area to monitor the HLB (Huanglongbing) infestation. Recommended actions for moving forward were identified and showed that is possible to use UAVs for detection of crop diseases with high precision.

Resposta do algodoeiro ao déficit hídrico em diferentes fases de crescimento.

Water deficit at certain cotton growth stages can cause severe damage to crop development, affecting physiological processes and reducing reproductive structures, with consequent yield losses. The objective of this study was to evaluate the response of cotton cultivars under water deficit applied at different stages of the crop cycle. We compared the number of bolls per meter, cotton yield, and water use efficiency for eight different cotton cultivars under a water deficit of 15 days. We selected the following growth stages: Emergence (EM), First Square (FS), First Flower (FL), Peak Bloom (PB), and First Open Boll (FOB). The control treatment was irrigated with 100% ETc. The experiment was conducted in Apodi, RN State of Brazil, semiarid region, using a sprinkler irrigation system. The number of bolls per meter, cotton yield, and water use efficiency were influenced by the interaction of cultivars x deficit periods. Lowest values were observed for water suppression in the FL and PB stages. When the water deficit was imposed in the initial stages of growth (EM to FS) or after the FOB stage, the cotton yield reduction was not significant. At the same stage and water deficit, the behavior of the different cultivars was similar. Producers are urged to take this information into account when developing irrigation schemes for cotton crops, thereby avoiding water deficits during the most critical periods of the crop cycle.