This study aimed to analyze fragments of rangelands through spectral responses and land cover change by livestock in regions of the Caatinga biome through remote sensing. For spectral behavior, the surface reflectance bidirectional (SRB) and spectral indexes of vegetation were used to verify the ragelands seasonality. Land cover change detection of Ouricuri and Tauá through Landsat-8 images with a 16-day revisit interval, were processed in the Google Earth Engine platform (GEE) and software Quantum GIS version 2.18 (QGIS). In the GEE platform, annual mosaics and stacking of the spectral bands were generated for the classification of images, and in sequence the production of thematic maps in QGIS. The analysis of land cover change considered the classes: thinned Caatinga, conserved Caatinga, herbaceous vegetation, bare soil, water and others. The analysis of the spectral responses showed that the vegetation monitored in Ouricuri presented higher SRB in the infrared band and lower SRB in the red and blue bands, and that caused the pasture to produce higher vegetation indexes than the other locations. Through validation, it was observed that in Tauá, there was an overall accuracy of 91% and Kappa index of 89%, and in Ouricuri there was an overall accuracy of 90% and Kappa index of 86%, indicating excellent correctness of the classification model. The classification model proved to be effective in verifying the temporal and spatial land cover change, making it possible to identify places with the vegetation that was most affected and susceptible to degradation and generation of political support to minimize damage to the Caatinga Biome.

Research focusing on energy, water vapor, and CO₂ exchanges over the Caatinga Biome is recent. Consequently, there exist research gaps on this topic that limit our ability to understand and project interannual and long-term variations in the CO₂ cycle of this environment. Thus, the objective of this study was to evaluate the behavior of the energy and CO₂ balances of the Caatinga Biome under extreme rainfall conditions (extreme drought and intense rainfall) using simulations of the SITE model (Simple Tropical Ecosystem Model). Meteorological data from the years 2009 (heavy rainfall) and 2012 (extreme drought) obtained from an INMET automatic station were used. Relationships between monthly GPP and NEE values and rainfall were also analyzed. Although the SITE model had been previously calibrated for the region, adjustments to the calibration were necessary for our study due to the extreme climatic values of the selected years. The results highlight the impact of rainfall on energy and mass exchanges over the Caatinga, particularly evident in the partitioning of the energy balance and the CO₂ balance. In 2009 (during heavy rainfall), the fraction of Rn converted into LE was nearly 6% higher compared to the values observed in 2012 (during extreme drought). Regarding CO₂, it was found that the Caatinga behaved as a sink, even under extreme drought conditions (2012), with annual average values of −1.86 µmol m⁻² s⁻¹ (2009) and −0.81 µmol m⁻² s⁻¹ (2012). Relationships between monthly GPP and NEE values and rainfall were also investigated, revealing an asymptotic relationship between the components of CO₂ balance and rainfall. It was evident that both the monthly values of GPP and NEE tend to stabilize when monthly rainfall volumes exceed 200 mm.

The objective of this work was to evaluate the effects of the inclusion of pelleted citrus pulp and microbial inoculant on the fermentation characteristics, carbohydrate and protein fractionation, and total digestible nutrient contents of 'Massai' grass (Megathyrsus maximus × Megathyrsus infestus) silage. The experimental design was completely randomized, in a 2×4 factorial arrangement (application or not of inoculant × 0, 10, 20, and 30% citrus pulp) with five replicates. There was an increase in dry matter recovery as affected by citrus pulp levels. The values obtained for pH and ammonia nitrogen indicated an adequate fermentation process. Under increasing citrus pulp levels, there was a reduction in neutral detergent fiber and an increase in nonfibrous carbohydrate contents and in protein linked to fiber. Total digestible nutrient content reaches a peak of 513.1 g kg1 with the inclusion of 12.50% citrus pulp. The microbial inoculant, when isolated, does not influence carbohydrate and protein profiles. Inclusions between 10 and 20% citrus pulp are able to maintain adequate fermentative parameters and improve the digestible nutrient profile, with an adequate dry matter recovery.

In Brazil, elephant grass has been used for thermal energy production, due to the high productivity, energy efficiency, biological nitrogen fixation (BNF) and biomass quality for energy generation by direct burning. The use of biomass depends mainly on the energy balance and biomass characteristics for energy production. The aim of this study was to evaluate the biomass of dry matter yield, qualitative biomass variables and energy balance of two elephant grass genotypes. The experimental design was completely randomized blocks with two elephant grass cultivars (Gramafante and Roxo) and four replications per treatment. Five cultivation cycles were studied. Biomass yield and the contents of acid detergent fiber, lignin, cellulose, ash and calorific value were evaluated. The biomass yields of elephant grass cultivars varied between 12 and 24 Mg ha-1, where the lowest yields were presented by the cultivar Roxo, and the higher yields by Gramafante. The contents of fiber, lignin, cellulose and calorific value did not vary among the genotypes studied. An energy balance was calculated for the complete biomass production lifecycle of elephant grass and the overall energy output/input ratio was 15.1:1. The results show that the elephant grass has highly suitable materials for the production of energy by direct burning. Key words: Pennisetum purpureum, agroenergy, dry matter.

Nutritive value of Tifton 85 hay ammoniated with urea