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Land use, land use change, and forestry accounted for two-thirds of Brazil's greenhouse gas emissions profile in 2005. Amazon deforestation has declined by more than 80% over the past decade, yet Brazil's forests extend beyond the Amazon biome. Rapid expansion of cropland in the neighboring Cerrado biome has the potential to undermine climate mitigation efforts if emissions from dry forest and woodland conversion negate some of the benefits of avoided Amazon deforestation. Here, we used satellite data on cropland expansion, forest cover, and vegetation carbon stocks to estimate annual gross forest carbon emissions from cropland expansion in the Cerrado biome. Nearly half of the Cerrado met Brazil's definition of forest cover in 2000 (≥0.5 ha with ≥10% canopy cover). In areas of established crop production, conversion of both forest and non-forest Cerrado formations for cropland declined during 2003-2013. However, forest carbon emissions from cropland expansion increased over the past decade in Matopiba, a new frontier of agricultural production that includes portions of Maranhão, Tocantins, Piauí, and Bahia states. Gross carbon emissions from cropland expansion in the Cerrado averaged 16.28 Tg C yr À1 between 2003 and 2013, with forest-to-cropland conversion accounting for 29% of emissions. The fraction of forest carbon emissions from Matopiba was much higher; between 2010-2013, large-scale cropland conversion in Matopiba contributed 45% of total Cerrado forest carbon emissions. Carbon emissions from Cerrado-tocropland transitions offset 5%-7% of the avoided emissions from reduced Amazon deforestation rates during 2011-2013. Comprehensive national estimates of forest carbon fluxes, including all biomes, are critical to detect cross-biome leakage within countries and achieve climate mitigation targets to reduce emissions from land use, land use change, and forestry.

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The rapid population growth has driven the demand for more food, fiber, energy, and water, which is associated to an increase in the need to use natural resources in a more sustainable way. The use of precision agriculture machinery and equipment since the 1990s has provided important productive gains and maximized the use of agricultural inputs. The growing connectivity in the rural environment, in addition to its greater integration with data from sensor systems, remote sensors, equipment, and smartphones have paved the way for new concepts from the so-called Agriculture 4.0 or Digital Agriculture. This article presents the results of a survey carried out with 504 Brazilian farmers about the digital technologies in use, as well as current and future applications, perceived benefits, and challenges. The questionnaire was prepared, organized, and made available to the public through the online platform LimeSurvey and was available from 17 April to 2 June 2020. The primary data obtained for each question previously defined were consolidated and analyzed statistically. The results indicate that 84% of the interviewed farmers use at least one digital technology in their production system that differs according to technological complexity level. The main perceived benefit refers to the perception of increased productivity and the main challenges are the acquisition costs of machines, equipment, software, and connectivity. It is also noteworthy that 95% of farmers would like to learn more about new technologies to strengthen the agricultural development in their properties.

The objective of this work was to analyze land use dynamics in the Brazilian Cerrado region from 2002 to 2013. This analysis was based on the interpretation of Landsat satellite images carried out by the projects Projeto de Conservação e Utilização Sustentável da Diversidade Biológica Brasileira (Probio) and TerraClass Cerrado 2013, both coordinated by Ministério do Meio Ambiente. In 2002, 38.9% of the Cerrado was covered by some type of anthropic activity. In 2013, this percentage increased to 43.4%. One of the main highlights is the emergence of a new agricultural frontier in the northern region of the study area, known as Matopiba.

The energy balance (EB) components were quantified in a commercial farm with corn crop, irrigated by central pivots, in the Northwestern side of São Paulo state, Southeast Brazil. The SAFER (Simple Algorithm For Evapotranspiration Retrieving) was applied to retrieve the latent heat flux (λE), considering six pivots, covering irrigated areas from 74 to 108 ha. With λE quantified and considering soil heat flux (G) as a fraction of net radiation (R n), the sensible heat flux (H) was acquired as a residual in the energy balance equation. Seven Landsat satellite images, covering all corn crop stages from 23 April 2010 to 29 August 2010, allowed relating the energy balance components according to the accumulated degree-days (DD ac) from the planting to harvest dates. The average R n values ranging from 5.2 to 7.2 MJ m-2 day-1 , represented 30 to 45% of global solar radiation (R G). Considering the variation of the energy balance components along the corn crop growing seasons, the average ranges for λE, H and G were respectively 0.0 to 6.4 MJ m-2 day-1 ,-1.5 to 6.7 MJ m-2 day-1 and 0.1 to 0.6 MJ m-2 day-1. The fraction of the available energy (R n-G) used as λE was from 0.0 to 1.3 indicated a good irrigation management, insuring that the water deficit could not be the reason of any yield reduction. Although R n did not reflected well the crop stages, its partition strongly depended on these stages. λE higher than R n and the negative H/R n , happened sometimes along the corn growing seasons. This occurred after the vegetative growth and before the harvest times, indicating heat advection from the surrounding areas to the irrigation pivots, which represented an additional energy source for the evaporative process. The models applied here with only the visible and infrared bands of the Landsat sensor are very useful for the energy balance analyses, considering the size of the corn crop irrigation pivots in Southeast Brazil, when subsidizing a rational irrigation water application in corn crop.

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Resumo -O objetivo deste trabalho foi analisar a composição florística e estrutural de sistemas silviagrícolas em Tomé-Açu, Pará. Os dados dendrométricos foram obtidos por inventário em 40 parcelas amostrais, com três unidades cada uma, no total de 120 unidades de 10x10 m. Foi inventariada a média de 1.424,3 indivíduos por hectare, pertencentes a 27 famílias e a 54 espécies. Tendo-se considerado a variabilidade dos estágios vegetativos, os diferentes sistemas silviagrícolas (SAF) foram divididos em quatro classes hierárquicas: SAF 1, SAF 2, SAF 3, e SAF 4, para estabelecer um sistema de classificação passível de ser utilizado em outras avaliações de campo e em classificações digitais por meio do sensoriamento remoto. Espécies observadas em outros sistemas da região amazônica também foram relevantes para este estudo, especialmente Theobroma cacao, T. grandiflorum e Euterpe oleracea que, juntas, apresentaram médias de frequência relativa de 51%, densidade relativa de 69,2%, dominância relativa de 50,1% e índice de valor de importância de 56,8%. Os dados médios de diversidade florística, abundância, área basal e valor de importância indicam os sistemas silviagrícolas da região de Tomé-Açu como sistemas de produção com potencial econômico e ambiental, se adotado manejo adequado e racional.Termos para indexação: agroecologia, Amazônia, integração lavoura-floresta, sistemas agroflorestais, uso da terra. Floristic and structural analysis of agroforestry systems in Tomé-Açu, Pará, BrazilAbstract -The objective of this work was to analyze the structural and floristic composition of agroforestry systems in Tomé-Açu, Pará, Brazil. Dendrometric data were obtained through an inventory of 40 sampling plots, with three sampling units each, comprising 120 sampling units with 10x10 m each. The average of 1,424.3 individuals per hectare belonging to 27 families and 54 species was inventoried. Considering the variability of vegetative stages, the different agroforestry systems (SAF) were divided into four hierarchical classes: SAF 1, SAF 2, SAF 3, and SAF 4, to set an classification system which can be used in other field evaluations and in digital classifications developed by means of remote sensing. Species observed in other agroforestry systems in the Amazon region were also relevant to this work, specially Theobroma cacao, Theobroma grandiflorum and Euterpe oleracea which, together, showed averages of 51% relative frequency, 69.2% relative density, 50.1% relative dominance, and 56.8% importance value index. The average data of the floristic diversity, abundance, basal area, and importance value index indicate that the agroforestry systems in the Tomé-Açu region are production systems with economic and environmental potential, if appropriate and rational management is adopted.