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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. [ABSTRACT FROM AUTHOR]

Simple Summary: Buffalo breeding in the Amazon biome can contribute significantly to local community development and, thus, is considered an essential income source. However, in Amazon regions, the inadequate breeding of these animals can lead to considerable negative consequences for the environment. Therefore, it is crucial to develop methodologies to improve animal management and grass yield. One of these methodologies is related to Precision Agriculture (PA), adapted for pasture and animal monitoring. Along these lines, we seek to utilize geostatistical techniques and remote sensing applications to better understand Buffalo grazing under a rotating system. In particular, we analyze forage Dry and Green Matter, as well as pH in pasture soils, demonstrating the obstacles against and advantages of the implementation of precise techniques for decision making and increasing grass productivity. We describe ways in which geostatistical soil pH mapping can be conducted, as well as the premises necessary to include remote sensing data in the analysis of pasture variables. Implementing these results in buffalo management systems can contribute to greater productivity and increasingly sustainable livestock. 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. [ABSTRACT FROM AUTHOR]

Despite the importance of oil palm, there is little research related to increasing the productivity of the palm under Brazilian conditions, especially in the Amazon region. The objective of the study was to evaluate the effect of phosphorus (P), potassium (K) and magnesium (Mg) on oil palm production during the productive period in the Brazilian Eastern Amazon. The experimental area consisted of 12.64 ha with 1824 trees, spacing was in equilateral triangle (9.00 m between trees and 7.80 m between rows). The adopted design was in randomized blocks, in a factorial scheme 4 × 3 × 2, consisting of four doses of P, three doses of K and two doses of Mg. The evaluation of the experiment began at the 6th year of plant age, and the components of oil palm productivity were evaluated: numbers of fruit bunches per tree (NB), fresh fruit bunches weight per tree (BW), bunch productivity (BP) until the 12th year of plant age. Foliar analysis was performed for the nutrients N, P, K, Ca, Mg and Boron (B). The application of phosphate source promoted increases in NB, BW and BP of oil palm during all the years evaluated. Increasing the K-fertilizer dose implied increases in BW and BP in oil palm trees during all years. The application of Mg-sulfate does not promote an increase in the yield components and foliar Ca and Mg concentration of oil palm, from the 6th to the 12th year of development. [ABSTRACT FROM AUTHOR]

Sunflower (Helianthus annuus L.) is an important oilseed crop with clear sensibility to salt stress. In this study, we evaluated silicon (Si) effect on the nitrogen metabolism and antioxidant enzyme activity in sunflower plants subjected to salinity. A 4 × 4 factorial arrangement of treatments in a completely randomized design with four replicates was used, consisting of four concentrations of Si (0.0; 1.0; 1.5; and 2.0 mM) and four concentrations of NaCl (0; 50; 100; and 150 mM) in the nutrient solution. The salinity reduced the nitrate content, but the increasing Si concentration in the medium improved the nitrate uptake, leading this ion to accumulate in salt-stressed plants, particularly in the roots. The nitrate reductase activity and the proline and soluble N-amino contents were also significantly increased by Si in salt conditions. The salinity increased electrolyte leakage and reduced the activity of enzymes superoxide dismutase, ascorbate peroxidase and catalase in sunflower plants, but these decreases were reversed by Si at 2 mM, thus alleviating the effects of salinity on these variables. We conclude that Si is able to positively modulate nitrogen metabolism and antioxidant enzyme activities in sunflower plants in order to alleviate the harmful effects of salinity. [ABSTRACT FROM AUTHOR]

The assessment of water quality is considered a tool of extreme importance for the conservation of water resources. In this context the objective of this research was to evaluate the water quality of different water courses in the municipality of Capitão Poço-PA. Water samples were collected from four water courses: Alencap, Riacho Doce, 23 of December and Virgílio, in which one was evaluated the fecal coliform index, dissolved oxygen in the water and pH. The fecal coliform index in the Alencap and 23 of December water courses were higher than 1600 NMP/100 ml, indicating a high level of pollution, which can pose serious health risks to the population. With respect to the dissolved oxygen level, Riacho Doce presented the highest number of 11.3 mg/ L, being considered the most appropriate for human use. The most unsuitable site for the dissolved oxygen variable was the Alencap water course, which presented only 1 mg/L. As for pH, it was possible to verify that all water courses presented acids, ranging from 4.0 to 5.5. There is a need for environmental awareness of the resident population in the municipality, especially in the community surrounding the water courses, in order to minimize the negative impacts of the pollution of these water resources. [ABSTRACT FROM AUTHOR]

Arruda belongs to family Rutaceae and contain important biological properties, presenting themselves as sources of coumarins, alkaloids and flavonoids. It is popularly known as arruda-stinking. The study aims to verify the best substrats and sowing depths for Ruta graveolens L. The experiment was conducted under greenhouse conditions at the experimental station the Universidade Federal Rural da Amazônia (UFRA) / Campus Capitão Poço. The experiment was carried out according to a complete randomized design with three replications, where each repetition has 15 seeds. The treatments were disposed in a factorial 3x5; the first factor consists of three different depths: Surface (S), 0.5 cm and 1.0 cm and different substrates, namely: Black Earth (BE); Black Earth + White Earth (BE + WE); Black Earth + Sawdust (BE + Sa); Black earth + Lump Acai Minced (BE + LAM); Black Earth + Rice Straw (BE + RS). The evaluated parameters were percentage of emergency and emergency speed index. The substrates x profundity of interaction, showed no significant difference. The seeds emergency in the surface, presented higher percentage of emerged plants. For seed placed at depths 0.5 and 1.0 cm, respectively. It was found that the different substrates have not provided significant differences both for percentage of emergency of the seeds as to emergency speed index. The seeds placed to emergency only on surface presents greater emergency percentage and just the use of black earth satisfies the emergency efficiency for this species. [ABSTRACT FROM AUTHOR]

Brazil stands out worldwide in the production of oil palm; however, there is a need to understand the interaction between the plantations and the environment. The objective was to evaluate the microbiological and chemical attributes of the soil in plantations of different ages of oil palm and of a secondary forest in two seasonal conditions. The microbiological variables analyzed were the carbon of the microbial biomass (CBMS), total carbon (CTOTAL), total nitrogen (NTOTAL), basal respiration (RB), metabolic quotient (qCO2), carbon / nitrogen ratio (C/N) and gravimetric humidity (Ug); (P), potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), effective cation exchange capacity (CTC) and aluminum saturation (% m). The chemical attributes of soil fertility and soil microbial biomass presented stronger and larger correlations in the rainy season. The most sensitive microbiological attributes to age of oil palm were CBMS, qCO2 and C/N ratio, while the chemical variables were P, Ca, Al, CTC, and pH in water. [ABSTRACT FROM AUTHOR]

The intensive farming systems are characterized by monoculture and the large-scale use of fertilizers and other agrochemicals. The use of tillage system and intercropping of grain crops, are examples of technologies that contribute to soil conservation. The objective was to evaluate the performance of maize crop by means of a intercropping with jack bean in the presence and absence of mineral fertilization, the experimental field of Universidade Federal Rural da Amazônia (UFRA), Campus of Capitão Poço, State of Pará. The experimental design used was a randomized block, with four replications, in a 2 x 2 factorial design consisting of four treatments resulting from the combination of single corn or jack bean intercrop presence or absence of manuring. The evaluated were the following characteristics in maize height of plants, culm diameter and number of leaves per plant, and 90 days after sowing (DAS) occurred harvesting of the cobs of corn, as well as measurement of length and diameter of cobs, number of rows of kernels, mass of 1000 seeds and grain production. The corn crop responded positively to green manure and mineral fertilizer. Besides there being a positive correlation with all the variables. [ABSTRACT FROM AUTHOR]

Cattle raising is one of the most important sectors of Brazilian agribusiness, in which Brazil is the world's fifth largest producer of milk. The objective of this study was to analyze the milk productivity behavior in the microregion of Guama, Para state in the period of 1997-2014. The data were time series of milked cows and milk production in Pará, specifically in the micro region of Guama, covering the period 1997-2014, provided by the Brazilian Institute of Geography and Statistics. The method used for data analysis was the shift-share that can be used to decompose the growth in milk production herd expansion effects and productivity. In 2014, milk production in the microregion of Guama was approximately 19033000 liters from 28565 milked cows, providing a yield of 666 liters cow-1 year-1. The productivity growth rate (income-effect) during the study period was higher in municipality of Cachoeira of Piriá with 2.22% per year, followed by Viseu, Aurora of Pará, Irituia and Mãe of Rio, with 2.12, 0.72, 0.30 and 0.21% for year, respectively. In the microregion of Guama the municipality that presented the best growth rates was Aurora do Pará, with values of 10.59% yield, 9.59% of milked cows. Except for the productivity was higher for Cachoeira of Piriá municipality with 2.22% for year. [ABSTRACT FROM AUTHOR]

The objective of the present study was to evaluate the population density effect upon yield components of sweet corn during two crop years. The experimental design used was the randomized complete blocks with four replications. The treatments were based on combination among sweet corn hybrids (Tropical Plus and RB-6324) and plant populations (40,000; 55,000; 70,000; 85,000 and 100,000 plants ha-1), in the factorial scheme 2 x 5, evaluated in two "Summer" crop years (2009 and 2010). The characteristics evaluated were number of rows per ear, number of grains per ear row, plant prolificacy and total husked ear yield, whose average values were submitted to the joint analysis of variance. In the year of 2009 for Tropical Plus and in the year of 2010 for RB-6324, the prolificacy decreased linearly until the maximum population of plants used, which presented values of 1.04 ear plant-1 and of 1.02 ear plant-1, respectively. A minimum value of prolificacy (1.08 ear plant-1) was observed for RB-6324 in 2009 with 92,935 plants ha-1. In 2009, the highest yields of husked ears for Tropical Plus (8.43 t ha-1) and for RB-6324 (9.88 t ha-1) were achieved with a density of 100,000 plants ha-1. On the other hand, in the second crop year, the yields increased quadratically from 51,848 plants ha-1 (7.78 t ha-1), for Tropical Plus, and from 57,648 plants ha-1 (9.32 t ha-1), for RB-6324, until the maximum population of plants evaluated, whereupon presented their respective maximum values of 12.04 t ha-1 and 12.31 t ha-1. In general, the increase in population was unfavorable to the prolificacy of plants, but did not impair the husked ear yield, for which it was noted better answers with a population of 100,000 plants ha-1, in both crop years and hybrids used. [ABSTRACT FROM AUTHOR]