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Effective calcium (Ca) management is crucial for optimizing oil palm cultivation and enhancing crop yield. This study aimed to gain insights into the dynamics of Ca concentration, accumulation, exportation, immobilization, and recycling in various oil palm organs relative to plant age. The experiment was conducted at the Agropalma enterprise site in the northeastern region of Pará State, Brazil, evaluating seven plant age treatments: 2, 3, 4, 5, 6, 7, and 8 years old. Employing a completely randomized design with four replications. The results demonstrated an age-related increase in Ca concentration in petioles, rachis, arrows, male inflorescences, peduncles, and fruits. Furthermore, Ca accumulation exhibited an upward trend in all organs with progressing plant age. Notably, the study revealed an enhanced Ca use efficiency across all plant organs in correlation with the age of oil palm cultivation. These findings underscore the dynamic nutritional demands of oil palm, influencing Ca immobilization, cycling, and export throughout its developmental stages. [ABSTRACT FROM AUTHOR]

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]

Eucalyptus plantations in the Brazilian savanna (Cerrado) are challenged by acidic soil and water-deficit conditions. Supply of Ca and S via application of dolomitic limestone and gypsum may stimulate root development (in terms of depth) and also enhance access to water stored in the subsurface layers. Aerial and root growth, Ca2+, Mg2+, K+, and S–SO42− migration, and soil profile of Eucalyptus urophylla were evaluated following dolomitic limestone and gypsum application. Five treatments were used: (i) no application of Ca2+, Mg2+, and S–SO42− sources (CONTROL); (ii) 1200 kg ha−1 of gypsum (GYP); (iii) 2000 kg ha−1 of dolomitic limestone (DOL); (iv) DOL plus 1200 kg ha−1 of gypsum (DOL + GYP); and (v) DOL plus 2400 kg ha−1 of gypsum (DOL + 2GYP). Compared with CONTROL, Gypsum and dolomitic limestone application in DOL + 2GYP increased the concentrations of Ca2+ and Mg2+ in the soil surface and of S–SO42− in the subsurface by five, four, and three times, respectively. Fertilization with gypsum alone or in combination with dolomitic limestone did not promote an increase in fine root density (FRD) in the deeper layers. Concentrations of Ca, S, and K in the leaves increased by 16–43%. Furthermore, applying limestone 49 months after planting increased E. urophylla whole wood volume and the mean annual increment (MAI) by 8%, as compared to those in the CONTROL. Thus, gypsum and dolomitic limestone positively impacted soil fertility and may be used to acclimatize Eucalyptus to water-deficit conditions. [ABSTRACT FROM AUTHOR]

Cedro-rosa (Cedrela fissilis) is native to Brazil with great potential for seedling production. However, soil correction is necessary to improve its performance, due to the edaphoclimatic conditions in Brazil, where soils have a high weathering degree and large amounts of Fe and Al oxides. Here, we evaluated the combined effect of soil acidity correction by liming and phosphate fertilization using single superphosphate on the growth and development of cedro-rosa seedlings cultivated in Amazonian soil. The study was carried out in a greenhouse at the Universidade Federal Rural da Amazônia (UFRA) - Campus Capitão Poço, between July and December 2019. Different levels of base saturation (V%) showed no influence on the variables analyzed. On the other hand, phosphorus (P), calcium (Ca), and sulfur (S) supplied by single superphosphate significantly influenced growth and development of cedro-rosa seedlings. The optimum P levels for stem diameter (SD), leaves number (LN), root dry matter (RDM), stem dry matter (StDM), leaf dry matter (LDM), total dry matter (TDM) were 405, 286, 385, 421.87, 393.75, 445 mg dm-3 of P, respectively. Seedling quality (DQI) showed a positive linear response to levels of P, Ca, and S in single superphosphate. Thus, fertilization with P was necessary at the nursery stage for the cultivation of the species in soil of low chemical fertility. For better quality of cedro-rosa seedlings grown in pots, the application of 400 mg dm-3 of P is recommended. [ABSTRACT FROM AUTHOR]

The availability and retention of phosphorus (P) in soils under recovery process after mining operations play an important role in the management of this nutrient. The objective of this study was to evaluate the P adsorption in a reconstituted soil as a function of two forest recovery processes after bauxite mining. We evaluated three systems: native forest (FOR), planting of forest seedlings after bauxite mining (TPL), and natural regeneration of vegetation after bauxite mining (NRV). In each system, eight sampling plots were deployed. In each plot, we collected litter and soil samples. The soil samples were collected at depths of 0–5, 5–10, 10–20, and 20–40 cm, for soil chemical analysis and adjustment of P adsorption isotherms. We also performed an inventory of the tree vegetation to obtain basal area (G) and species diversity (H′). Forest was significantly superior with respect to most soil fertility, litter, and vegetation attributes, followed by natural regeneration and planting. In general, the adsorption curves and maximum phosphorus adsorption capacity (MPAC) in soil followed the order planting > natural regeneration > forest. We observed a negative relationship between phosphorus adsorption and soil organic matter, potential acidity, and available phosphorus. This result highlights the importance of biomass conservation and maintenance to ensure phosphorus availability in reclamation practices. Furthermore, such results indicate that both soil cover and plant species diversity should be considered when selecting species to improve P availability for reclamation of mined areas. [ABSTRACT FROM AUTHOR]

Oil palm production is strategic in the Amazon with high productive potential, but information on its fertilization is still relatively scarce for the region. The objective of this work was to evaluate the effects of phosphorus, potassium and magnesium fertilizations on oil palm production in different years in the state of Pará, Brazil. The study was conducted in Tailândia, Northeastern of Pará, Eastern Amazon, Brazil. A randomized block design was used in a 4 x 2 x 3 x 2 factorial scheme, with four levels of phosphorus, two sources of phosphorus, three levels of potassium and two levels of magnesium. Oil palm production responded positively to the increase in phosphorus levels, and until the eighth year of age of the plants, there was greater production when triple superphosphate was applied. From the ninth year onwards, fertilization with phosphine provided a production equal to the supply of phosphorus with triple superphosphate. The application of potassium chloride increased the number, weight and production of the bunches from the sixth year. The supply of magnesium sulfate increased the average weight of the bunches. Thus, phosphorus, potassium and magnesium fertilizations become essential to increase oil palm production in the Northeast of Pará. [ABSTRACT FROM AUTHOR]

The concentrations of nutrients in the leaves allow a better understanding of the nutritional status of oil palm plants, making it a tool for diagnosing the origins of nutritional problems and assisting in fertilizer recommendations. In this sense, the objective of the current research was to evaluate the leaf concentrations of N, P, K, Ca, Mg and S in the oil palm under fertilization with phosphate, potassium and magnesium in edaphoclimatic conditions of Eastern Amazon. The experiment was conducted at the AGROPALMA® Company in the municipality of Tailândia, state of Pará, Brazil. The experimental design used was randomized blocks in a factorial scheme 4 x 2 x 3 x 2, with four levels of phosphorus, two sources of phosphorus (natural phosphate and triple superphosphate), three levels of potassium and two levels of magnesium. Phosphorus fertilization increased the leaf concentrations of N, P, Ca and Mg, providing higher levels when triple superphosphate was applied. However, in adult oil palm plants (12 years old), there was different on leaf concentrations of N, P, K and S between phosphorus sources aphid. Potassium and magnesium fertilization only increased the leaf concentrations of K and Mg, respectively. Fertilization with P, K and Mg promotes adequate leaf concentrations of K, Ca, Mg e S in oil palm plants grown in the Eastern Amazon. [ABSTRACT FROM AUTHOR]

In the northeastern of Pará, cowpea is one of the main protein sources of the population. This study aimed to evaluate the effects of liming, the P and K mineral fertilization, and the combination of seed inoculation with Rhizobium associated with mineral N supplementation in the growth and production of cowpea cultivars. Two experiments were carried out in two consecutive years at the Federal Rural University of Amazonia (Capitão Poço-PA). A randomized block experimental design with subdivided plots was used with four replications, two cowpea cultivars (BRS Tapaihum and BRS Marataoã) and six fertilization and liming treatments: i) without fertilization and without liming; ii) P and K mineral fertilization, liming and seed inoculation with Rhizobium; iii) P and K mineral fertilization and seed inoculation with Rhizobium; iv) N, P and K mineral fertilization and liming; v) P and K mineral fertilization and liming; and vi) N, P and K mineral fertilization, liming and seed inoculation with Rhizobium. Cowpea responded to liming and P and K mineral fertilization, but not N fertilization. There was no difference between the supply of N through seed inoculation or mineral fertilization. Thus, it is suggested to inoculate seeds with Rhizobium in order to maintain the soil N reserve. [ABSTRACT FROM AUTHOR]

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Eucalypt plantations in Brazil have the highest mean productivity when compared to other producing countries, and fertilizer application is one of the main factors responsible for these productivities. Our aim was to identify appropriate rates of N, P and K in eucalypt plantations and their interactions with edaphoclimatic factors. Four trials with four rates and three nutrients (N, P and K) were set up. Each nutrient was studied separately, and the trees received sufficient rates of all of the other nutrients through fertilization, to avoid limitations not related to the desired nutrient. We assessed solid wood volume (SV), productivity gains (PG), leaf nutrient content and leaf area index (LAI) to determine the responses to fertilization. PG, regarding N, rates ranged from 104% to 127% at 60 months after planting. P fertilizer application led to gains in productivity in soils with levels of P-resin up to 5 mg kg-1, but decreased with stand age. K fertilizer application responses increased within age in three sites. In Paulistania, responses to K application were close to zero. N and K responses were climate related. Leaf nutrient content and LAI were not able to predict the highest yields obtained. [ABSTRACT FROM AUTHOR]

The order Isoptera is well known by its potential as a plague, although the number of species that are plagues is small within the group. Termites are the dominant invertebrates in tropical terrestrial environments and are spread from tropical rainforests to the savannahs, being found even in arid regions, in various habitats. These insects have a major role and are still little studied in tropical ecosystems. Nutrient cycling, aeration, water infiltration of soil, bioturbation, aggregates formation and organic material decomposition, are processes influenced by the action of termites, which , directly or indirectly, affect soil and landscape formation wherever they are. We suggest that a better approach must be addressed in future researches about these insects influence in the soil under specified conditions of use and management, in sustainable food production and climate changes. [ABSTRACT FROM AUTHOR]