Por muitos anos as produções agropecuárias foram as principais causas do desmatamento na Amazônia Legal, principalmente após as políticas desenvolvimentistas para região amazônica, a partir da década 60. Neste contexto, objetivou-se analisar no período de 2002 a 2017, a dinâmica espaço-temporal do uso e cobertura do solo nos municípios maranhenses situados na Amazônia Legal. O estudo aconteceu em 170 municípios que fazem parte do território da Amazônia Legal. Utilizou-se para aplicação do coeficiente de correlação, os dados referentes às áreas desmatadas, área total utilizada na agricultura e quantidade de bovinos. Empregou-se também os dados de área territorial e estimativa populacional dos municípios de maior área desmatada. Observou-se que o desmatamento na Amazônia Legal, no Maranhão, teve expressiva redução de 131.428 hectares, entre os anos de 2002 a 2017. Em contraste a isso, o número de bovinos e a área utilizada na agricultura aumentaram de 4,33 para 7,098 milhões e 1,052 para 1,573 milhões de hectares, respectivamente. O desmatamento da Amazônia Legal no Maranhão, em 16 anos, esteve amplamente (70%) concentrado em 25 municípios, principalmente os localizados próximos a importantes rodovias federais ou com fácil acesso a outros estados, como o Pará. Embora, os indicadores de desmatamento na Amazônia Legal situada no Maranhão, indiquem que há redução em 16 anos, é necessário atentar ao desenvolvimento sustentável na agropecuária, ou seja, equilíbrio entre o econômico, ecológico e social, pois há muito que pode ser preservado, ainda. Também é importante a adequada fiscalização ambiental em áreas de divisa do estado, que demonstram uma forte tendência a impactos ambientais, associados ao desmatamento.
This study applied spectroradiometry techniques with hyperspectral data to identify the correlations between sugarcane leaf reflectance and the contents of Nitrogen (N), phosphorus (P), Potassium (K), Sulfur (S), Calcium (Ca) and Magnesium (Mg). During the harvests 2019/20 and 2020/21, sugarcane was introduced to nutritional stress by the application of limestone doses. Liming was applied in a fractional way and, at the end of five years, the amounts corresponded to 0, 9, 15 and 21 t ha-1 of dolomitic limestone. The leaf hyperspectral reflectance data and the state of nutrients in the exponential growth phase of the culture were registered. The wavelengths correlated with N, P, K, S, Ca and Mg were identified using the Spearman’s correlation analysis. The test of similarity (ANOSIM) and the Principal Component Analysis (PCA) were applied to evaluate data variability, as well as the Partial Least Squares Regression (PLSR) for the prediction of the nutritional contents. The order of the degree of correlation in the region of visible was: P > K > N > Ca > S > Mg and for the region of the near infrared: P > K > Ca > N > S > Mg. P presented peaks with high correlations in the wavelengths 706-717 nm (-0.78) and 522-543 nm (-0.76). The values of the PLSR registered the best spectral responses in the region of VIS and red-edge, regions that are more sensitive to the deficiency of sulfur, potassium and phosphorus.
The protection conferred via chemical treatment of seeds is indispensable to the normal development of crops, with a view to the best use of its productive potential. The objective of this study was to evaluate the soybean crop response, cultivate ‘FTS Paragominas RR’, to seed treatment. The study was conducted in an experimental area of the Center of Agrarian and Environmental Sciences of the Federal University of Maranhão, in Chapadinha (MA), from February to June 2018. A randomized complete block design was used, with split-plot in time. The plots consisted of five seed treatments: thiophanate-methyl + fluazinam fungicides, fludioxonil, carbendazim + thiram, the insecticide fipronil and the absence of the application. Throughout the crop cycle the agronomic characteristics were verified: plant height, stem diameter, and leaf area. And, at the time of harvesting, grain yield, the height of insertion of the first pod, the total number of pods and weight of 1000 grains. Seed treatments induced very variable responses on the growth and development of soybean ‘FTS Paragominas RR’. The best performances were obtained with the use of thiophanate-methyl + fluazinam fungicides (dose 198 mL) and fludioxonil (dose 200 mL). The application of carbendazim + thiram and fipronil, both at a dose of 200 mL, presented adverse effects throughout the vegetative and reproductive phases of soybean ‘FTS Paragominas RR’. None of the products provided significant increases in grain yield.
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