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In the present work, the vegetation indices obtained from satellite images are used to monitoring sugarcane crop. The study was carried out in 5,5 ha of sugarcane field, planted with CP 52-43 variety located in Camajuaní Municipality, Cuba. Vegetative evolution of the plantation was monitored by field measurements of leaf width, stem diameter, stem height, soil moisture and vegetal cover, using the diagonal distribution method for samples collection. The services available in Earth Observed System (EOS) were used to obtain images of vegetative index of: NDVI, SAVI, EVI and NDWI. The initial stage of crop was characterized by low values of soil moisture and foliar development of sugarcane plants, EVI and NDVI indices showed results according to the low vegetative development with values between 0,2 and 0,4, while NDWI agreed with dry soil. In the rainy season, after the fourth month of the plantation, an increase in soil moisture to 42,9% took place, the plants' biophysics parameters: stem height, stem diameter and leaf width also increased, EVI index reached between 0,6 and 0,8 in 74,4% crop area and in the same way NDVI index showed values between 0,7 to 0,8. However, NDWI index showed values between -1 and -0.6 belonging to dry soil, no matching with the actual moisture conditions. Through monitoring with Sentinel-2 satellite, a more stable representation of the increase in vegetation was achieved, as well as more adequate values of the initial and final state of the crop were obtained. [ABSTRACT FROM AUTHOR]

Analysis of energy use efficiency provides an assessment of non-renewable energy consumption; it is a useful indicator of environmental and long-term sustainability when comparing cropping systems. This study aimed to estimate the energy use efficiency of organic and conventional cropping systems of sugarcane for sugar production in central Cuba. Estimation of the energy use efficiency included analysis of four cropping systems. The energy input in the field until harvest and transport to the sugar mill was the limit of this analysis. The results showed that organic cropping systems were less efficient in energy use because of the greater number of field operations, mainly for weed control by manual and mechanical cultivation. Organic cropping systems also had lower yield compared with conventional systems due to their use of low doses of organic products, instead of agrochemical fertilizers, for plant nutrition. In all cropping systems evaluated, sugarcane used for seed was the largest part of the energy input due to the consumption of 12 t ha-1 of seed, representing an average of 89% of the total energy input for the sugarcane cropping systems. The second largest part of the energy input was the fuel consumed during mechanized operations. Irrigation was the third largest part of the energy input for organic cropping systems and the second largest part of the energy input for conventional cropping systems. [ABSTRACT FROM AUTHOR]

The unavailability of chemical fertilizers to obtain high yields in Cuban agriculture has led to the development of other organ-mineral fertilizers, such as Agromena - G, produced by the Empresa Geominera del Centro in Villa Clara. The objective of this work was to characterize the organ-mineral fertilizer Agromena - G, based on the determination of the main physical and chemical properties of the fertilizer for its mechanized application in the improvement of soils and the increasing of crops yield. The methodology included the determination of physical properties as granulometry, apparent density and humidity of the organ-mineral fertilizer. In addition, chemical properties such as pH, electrical conductivity, available phosphorus and organic matter were determined. The physical properties of the organ-mineral fertilizer Agromena - G, show that its granulometry (approximately 50% of the grains smaller than 1 mm) favors its use since it facilitates its acquisition by the plants. The other determined properties behave within acceptable values for the most common granular fertilizers. The physical properties of this fertilizer favor its mechanized application both by broadcast fertilizing machines and with machines for localized fertilization. The chemical properties of this organ-mineral fertilizer demonstrated its potential use as an alternative for managing plant nutrition although it is recommended the surveillance of indicators as electrical conductivity and cations concentrations, especially Na+, in clayed soils susceptible to salinity problems. [ABSTRACT FROM AUTHOR]

The constitutive models of critical state are among the most employed for soil compaction simulation by means of finite element method. This paper has the objective to determine the influence of soil bulk density on elastoplastic parameters of Rhodic Ferralsol soil. Triaxial and compression uniaxial tests were carried out to remoulded samples, with a bulk density of 1.1; 1.175; 1.25 Mg m-3, and gravimetric moisture content of 25 kg g-1. The obtained values of variables analyzed can be used as input data to modeling soil compaction by finite element method and allow to know critical state variables behaviour of one of the Cuban soils with major economic importance. [ABSTRACT FROM AUTHOR]