The aim of this study was to economically estimate the effect of inoculation with Azospirillum brasilense (A. brasilense) associated with enhanced efficiency nitrogen fertilizers on corn yield cultivated in the Brazilian Amazon. The experimental design used was completely randomized, in a 2 × 3 × 5 factorial scheme, resulting from the combination of the presence and absence of seeds inoculated with A. brasilense, three sources of N (conventional urea, urea with NBPT, N-(n-butyl)thiophosphoric triamide, and polymer-coated urea), and five doses of N (0; 50; 100; 150; and 200 kg ha⁻¹ of N), with six replications. Inoculation with A. brasilense promoted profit in corn, regardless of dose and the source of N applied. The urea with NBPT provided better economic return compared to polymer-coated urea and conventional urea sources, and doses of N applied in topdressing that promoted the highest economic return were 100 and 150 kg ha⁻¹ of N, with an estimated increase of 62.33 and 135.53 bags ha⁻¹ and increase of BRL 3253.76 and BRL 7074.88 respectively, compared to the control treatment.

The mapping of pastures can serve to increase productivity and reduce deforestation, especially in Amazon Biome regions. Therefore, in this study, we aimed to explore precision agriculture technologies for assessing the spatial variations of soil pH and biomass indicators (i.e., Dry Matter, DM; and Green Matter, GM). An experiment was conducted in an area cultivated with Panicum maximum (Jacq.) cv. Mombaça in a rotational grazing system for dairy buffaloes in the eastern Amazon. Biomass and soil samples were collected in a 10 m × 10 m grid, with a total of 196 georeferenced points. The data were analyzed by semivariogram and then mapped by Kriging interpolation. In addition, a variability analysis was performed, applying both the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) derived from satellite remote sensing data. The Kriging mapping between DM and pH at 0.30 m depth demonstrated the best correlation. The vegetative index mapping showed that the NDVI presented a better performance in pastures with DM production above 5.42 ton/ha⁻¹. In contrast, DM and GM showed low correlations with the NDWI. The possibility of applying a variable rate within the paddocks was evidenced through geostatistical mapping of soil pH. With this study, we contribute to understanding the necessary premises for utilizing remote sensing data for pasture variable analysis.

With the increase in prices of correctives and fertilizers, the investigation of the interactions between plants and plant growth-promoting bacteria shows an economically viable and sustainable alternative, and the use of Azospirillum brasilense has shown an increase in efficiency of nitrogen use and increased pasture yield. This study, conducted in the Brazilian Amazon, aimed to evaluate the effect of different inoculation techniques of Azospirillum brasilense associated with the dose of nitrogen topdressing on the productive performance of Brachiaria brizantha cv. Paiaguás is a grass species commonly cultivated in this region. The experiment was conducted in the Experimental Forage Sector of the Federal Rural University of the Amazon, Parauapebas city, Brazil. The experimental design was a randomized block design in a 3 × 3 factorial arrangement, with three inoculation methods (control, seed, and foliar) and three nitrogen fertilization doses (0, 75, and 150 kg ha⁻¹ of N), with four replicates. An effect was observed in interaction between inoculation and nitrogen fertilization (p ≤ 0.05) for the variables total forage green mass, total forage dry mass, dry mass of leaf blade, dry stem mass, and number of tillers m⁻². The dose of 150 kg ha⁻¹ of N promoted a positive effect of N on the total forage dry mass and LAI (leaf area index). Inoculation with Azospirillum brasilense, especially foliar application, efficiently increased Brachiaria brizantha cv. Paiaguás yield, potentially reducing the use of nitrogen fertilizers, promotes greater sustainability in pasture management.

RESUMO: As atividades relacionadas à mineração são causadoras de enormes alterações na estrutura e na dinâmica da paisagem, sendo fundamentais estudos da diversidade florística para elaboração de estratégias de conservação da biodiversidade. O objetivo do estudo foi analisar a composição florística em floresta de várzea, próximo a ambiente impactado por atividades mineradoras, localizada ao longo do rio Parauapebas. Foram instaladas 13 parcelas fixas de 10 x 10 m (10 m2), alocadas de forma sistemática na área de mata ciliar, ao longo da margem do rio Parauapebas, município de Parauapebas, PA. Por meio dos resultados do experimento foram identificadas 23 famílias distribuídas em 18 gêneros e 30 espécies. As famílias com maior número de espécies foram Fabaceae (11), Malvaceae (3) e Rutaceae (2). O gênero com maior riqueza em espécies foi Inga sp., com 3 espécies diferentes, respectivamente. A família Fabaceae representou 32% das espécies coletadas, Malvaceae 10% e Rutaceae 6%. Das espécies amostradas, uma foi exótica, representada pelo Citrus limon (L.) Osbeck (limão-galego) e o indivíduo com maior representatividade foi Sterculia chicha A. St. -Hil., presente na maioria das parcelas. Apesar do fragmento encontrar-se ameaçado por ações antrópicas, a variedade florística no local apresenta-se bastante diversificada, com espécies pioneiras, secundárias e clímax.PALAVRAS-CHAVE: Composição florística, Flora amazônica, Riqueza.

The application of precision agriculture in cocoa and papaya cultivation in Brazil is still incipient. This study aimed to evaluate the spatial variability of the physical attributes of soil cultivated with a consortium of papaya and cocoa. The study was conducted in two sampling grids of 50 points, in two areas cultivated with papaya and cocoa with different planting times (three and eleven months). The soil attributes soil resistance to penetration (RP) and soil gravimetric moisture (UG) were determined at soil depths of 0–20, 20–40 and 40–60 cm. The data were submitted to an exploratory and descriptive analysis. Subsequently, a geostatistical analysis was performed to quantify spatial dependence and then interpolation of the data through kriging. The maps showed weak spatial variability for the UG and RP. In the two areas, it was observed that the depth of 0–20 cm had a lower RP (1.7 Mpa) and a higher UG (40 g g⁻¹), and as the depth was higher, had a higher RP (4.4 Mpa) and a lower UG (38 g g⁻¹). Area 1 presented higher RP values in depth, showing greater susceptibility to compaction. The area characterized by the consortium of papaya and cocoa presented more susceptible to compaction. The mechanical resistance of the soil to penetration was more critical in the 40–60 cm layer for the two consortia evaluated, evidencing areas with possible restriction to plant growth.

O objetivo do estudo foi realizar o diagnóstico físico e químico das águas e a caracterização de nascentes da Universidade Federal Rural da Amazônia no município de Parauapebas – Pará. As amostras de água foram coletadas de três nascentes e realizadas análises nos anos de 2017 (22 de Março à 12 de Agosto) e 2018 (10 de Março à 05 de Junho). No campo foi aferida à temperatura da água das nascentes e, as medições de pH e condutividade elétrica foram realizadas no Laboratório de Solos da UFRA. As três nascentes avaliadas foram classificadas como intermitentes com influência da precipitação pluvial e da matéria orgânica nos valores de pH e condutividade elétrica. Pelos resultados da correlação entre as nascentes associadas aos valores de pH e condutividade elétrica da água verificou semelhança nas três nascentes, justificada pela proximidade das mesmas, caracterizando como uma única nascente.