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Oil palm is the main palm tree cultivated in the tropics, but little is understood about copper (cu) management in this crop. The objective of this study was to evaluate the nutritional status of copper in oil palms plants in the Eastern Amazon. The experiment was carried out in Tailândia, in the state of Pará (Brazil), using a completely randomized experimental design, with four replications and seven treatments (ages of oil palm plants: 2, 3, 4, 5, 6, 7, and 8 years). The concentration, accumulation, cycling, immobilization, export, and efficiency of copper use in the different organs of the plants were evaluated. The highest copper concentrations occurred in the palm heart in the second year, and copper accumulation (481 g ha−1) and export were highest in the eighth year of growth. Among the plant organs, the highest copper exports occurred in the bunches (69.38 g ha1). The highest proportion of copper was immobilized (326 g ha−1), while the lowest proportion of the nutrient accumulated in the export organs. Copper use efficiency increased with plant age, and efficiency was greater in the petiole and lower in the palm heart. The copper requirement increased with the age of oil palms grown in the Eastern Amazon. [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]

Cupuaçu (Theobroma grandiflorum Schum) is a small tree species that belongs to the family Malvaceae and is native to the Amazon. Forests capture and fix carbon in their components. Knowledge about carbon fixation in cupuaçu is incipient. The objective was to determine the biomass and the carbon stock in the components of two progenies of cupuaçu trees of different ages. The study was developed at the experimental station of Embrapa Amazônia Oriental, in Belém-Pará, Brazil. Seventy individuals were selected from the progenies PMI 186 and PMI 215, annually for seven years, to determine biomass and carbon stock in four plant components: stalk, leaves, primary branches and secondary branches. The mean biomass for stalk, leaves, primary branches and secondary branches were, respectively, 1352.5; 2412.0; 1748.5 and 2672.1 kg ha-1. In the same order, the average carbon stock was 507.9; 892.3; 647.6 and 988.9 kg ha-1. Cupuaçuzeiro presents low carbon stock in relation to other Amazonian species, but this plant can be adopted for cultivation because of the economic benefits that this activity generates. [ABSTRACT FROM AUTHOR]

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]

Geo-statistics are a great help in management strategies, improves efficiency in the production process and reduces environmental impacts. Current paper works on a hypothesis which consists of spatial dependence of soil attributes on soil management systems. Study characterizes the spatial variability of soil resistance to penetration, gravimetric moisture and active acidity in soil management systems in the Brazilian Amazon. The experiment was conducted on an experimental area in Parauapebas, southeast Pará, with four management systems: native forest (MN), no-tillage system (SPD), conventional planting system (SPC) and pasture (PAS). A 200 m x 100 m sample was established, with a 25 m x 40 m spacing, totaling 30 sampling points per management system. Soil resistance to penetration (PR), soil gravimetric moisture (Ug%) and active soil acidity (pH) were evaluated at depths 0.0-0.10 m; 0.10-0.20 m; and 0.20-0.30 m. Data were analyzed by descriptive statistics and geostatistical analysis. PR, Ug% and active soil acidity were normal in data distribution, with coefficient of variation rates lower than 25%. In the geostatistical analysis, PR, Ug% and pH showed spatial dependence on systems and depths evaluated. In the analysis of geostatistical maps, specific zones with critical PR, Ug% and pH standards were verified. Localized management measures may be applied for each level of compaction and/or acidity higher than the critical limit, which reduces costs with soil management practices. [ABSTRACT FROM AUTHOR]