Abel W. de Albuquerque

Growth and yield of sugarcane under different phosphorus sources

This work had as its objective in the evaluation of the growth and production of the sugarcare plant under different phosphorus sources. The experiment was carried out in Coruripe, AL, Brazil with 10 fertilizer treatments: 1) Control; 2) NK + micronutrient; 3) Super Phosphate Simple; 4) Triple Super Phosphate; 5) Fosmag; 6) Gafsa; 7) MAP; 8) NPK 06-26-24 (460 kg ha-1); 9) Compost and 10) Simple Super Phosphate - splitdose. The experiment was in random blocks, with four replicates. Parameters evaluated were: number of tillers, height of plants, IAF, rate of stalk growth, rate of biomass production of the stalk, relative growth rate, production and P in leaf and available in soil. P sources did not show any significant influence upon the growth of cane-plant due to the residual effect of previous manuring, with average yield of 80 t ha-1. The triple super phosphate produced the best production in the cane-plant, which presented three growth phases: 1st phase: intense tillering until 120 days after planting (DAP); 2nd phase:intense growth between 120 and 240 DAP; and 3rd phase: maturation, between 240 and 360 DAP. The major growth rate and fresh matter stalk production occurred after intense tillering phase between 120 and 240 DAP.

Adubação nitrogenada para o milho cultivado em sistema plantio direto, no Estado de Alagoas

The objective of this work was to evaluate the effects of nitrogen doses upon production components of corn cultivated under a no-tillage system. Four nitrogen rates (0, 40, 80 and 120 kg ha-1) and five cultivars (AG-9010, TRACTOR, DOW-8550, DKB-395 and AL-34) were used. For all treatments, except for the control 20, 115, 60 and 4 kg ha-1 of N, P205, K2O and Zn were applied, respectively. The statistical design was the completely randomized block with four replications in a split plot scheme. The yield components studied were: plant population at harvest, ear length, number of grain rows per ear, ear number, and mass of 100 grains. The yield of the germoplasm varied from 1,900 kg ha-1 for the control to 5,662 kg ha-1 for the highest N dose (120 kg ha-1). For yield, it was observed that the hybrids DOW-8550 and AG-9010 were the most promising. It may be concluded that the economic return of the N fertilization can be reached with a 120 kg ha-1 dose. Both hybrids and cultivars used showed high efficiency in the use of the applied N, the hybrids being more responsive than the varieties.

Fluxo difusivo de fósforo em função de doses e da umidade do solo

The main phosphorus transport mechanism in the soil is diffusion, which is influenced by several soil factors, such as volumetric water content, phosphorus-colloid interaction, distance between source and roots, content and temperature. The effects of the soil water content and phosphorus doses on the diffusion flow into soil were assessed in samples from the superficial layers of five soils. The treatments were arranged in a 5 x 8 x 5 factorial design corresponding, respectively, to five soils, eight moisture levels and five phosphorus doses. A completely randomized block design with four replications was used. The experimental unit was a PVC ring with a volume of 360 cm3, which acted as a diffusion chamber. Anionic exchange resin slides (IONICS 204UZRA) were utilized to assess the phosphorus diffusion flow. Results indicated that the diffusion flow was influenced by phosphorus doses and moisture content.

Manejo da cobertura do solo e de práticas conservacionistas nas perdas de solo e água em Sumé, PB

The effect of the soil cover management and conservation practice on soil and water losses caused by the erosivity of rainfall in Haplargid soil have been analyzed in this paper. The field data corresponding to the years 1983-1990 were collected at the Experimental Basin of Sume, PB operated by the Federal University of Paraiba (UFPB). The experimental data resulting from one erosion plot cleared bare of vegetation and continuously ploughed in, two cleared bare runoff plots, one runoff plot with native semiarid vegetation, two mulched runoff plots, one plot with cactus planted down the slope and one plot with cactus planted along contour lines were used in the analysis. The bare ploughed plot contributed with annual soil and water losses of 23.1 t ha-1 and 201 mm respectively. In the cleared runoff plots, the soil losses were of 35.7 and 58.5 t ha-1 and the water losses of 224.2 and 241.0 mm, respectively. The runoff plot with native semiarid vegetation when compared with the bare runoff plots, showed a reduction in the soil losses of about 99% and the water losses of around 89%, while in mulched runoff plots there was a reduction of approximately 99% of soil losses and 74% of water losses when compared with the bare plots. The contour planted cactus plot reduced the soil losses by about 53.4% compared with the down the slope planted cactus plot.

Determination of the factors of the universal soil loss equation in Sumé (Paraíba State, Brazil)

The Universal Soil Loss Equation (USLE) factors were determined in a Haplargs under natural rainfall conditions. Data concerning to the years of 1983 -1990 were obtained at the Sume Experimental Station (Paraiba State - Brazil) of the Federal University of Paraiba (UFPB). The treatments consisted of runoff plots with bare soil, native semiarid vegetation runoff plot, mulch runoff plot, palm leaf under downhill runoff plot and under contour palm leaf runoff plot. The annual average of the rainfall erosivity factors EI30 and PI30 were 4,928 MJ mm ha-1 h-1 and 19,734 mm-2 h-1, respectively. The calculated annual mean values of the erodibility parameters were calculated in 0.013 t h MJ-1 mm-1 and 0.003 t h ha-1 mm-2. The calculated values for the support practice factor cropping-management parameter were 0.0015, 0.0174, 0.0133, 0.0056, 0.5103 and 0.2355 for the native semiarid vegetation runoff plot, native semiarid vegetation (new) runoff plot, mulch runoff plots, downhill palm leaf runoff plot and contouring cropped palm leaf runoff plot treatments, respectively. The values of the support conservationist practice factor to downhill palm leaf runoff plot was 0.46.

Índice de área foliar e produtividade do tomate sob condições de ambiente protegido

The tomato cultivation in the greenhouse has been expanded in the last years, mainly, in the South and Southeast regions of Brazil, whose purpose is to improve the productivity and the quality of the agricultural products, offering regularity in the production. The present study aimed to determine, along the crop cycle, the relationship between the leaf area index and the productivity, and at the end of the cycle, the components of production of the tomato in the greenhouse. The models were generated through polynomial equations of 1st and 2nd order, having as independent variable the number of days after the transplanting. It was verified that it is possible to determine, in the greenhouse, through mathematical models, the leaf area index of the tomato crop considering the days after the transplanting. Basing on values of leaf area index, the productivity of the crop and the period of the maximum productivity can be determined, aiding the farmers to determine the best sowing and transplanting time of the tomato crop.

Arranjo espacial de plantas de milho em sistema plantio direto

The interaction of management practices that increases plant density and reduces row spacing by spatial arrangement, if well planned, can be an excellent opportunity for the producers to increase their profitability. The objective of this study was to evaluate the variation effects of plant spatial distribution in two maize hybrids cultivated in a no-tillage system on the production components. The study was conducted in the CECA/UFAL. The treatments consisted of the cultivation of two hybrids of maize, FORT and AGN 30A00, in row spacings of 0.80 and 0.40 m and with plant densities of 60,000 and 70,000 plants ha-1. The statistical design was randomized blocks in a 2 x 2 x 2 factorial scheme, with three replications. From the results obtained, it may be concluded that neither the row spacing reduction nor plant density increase, as isolated practices, do not increase grain yield in the tested cultivars. The association of the reduction in row spacing and increase in plant population resulted in significant gain in grain productivity for the hybrid FORT.

Plantas de cobertura e adubação nitrogenada na produção de milho em sistema de plantio direto

The cultivation of cover crops can optimize the input of organic material and nutrients and protect the soil from erosion, while the N is one of the most required nutrient by agricultural crops and may become a limiting fator in its productivity. In this context, an experiment was carried out to evaluate the influence of three different legumes used as cover crops on morphological components and production of corn grown in succession under no-tillage system, in the absence and presence of mineral N fertilization (80 kg N ha-1), in the form of ammonium sulfate. This study was conducted in an Oxissol of the Coastal Tablelands in the State of Alagoas. The components of maize production showed better results in succession to Crotalaria spectabilis. Significant interaction was found between green manure and N fertilization, resulting in higher grain productivity.

Production of helicônia Golden Torch as influenced by the mineral and organic manure

The cut tropical flower market in Alagoas-Brazil demands articulate actions in the production chain to reduce costs with mineral fertilizers that represent a significant percentage of the production costs. This work had the objective of evaluating the production components of the tropical flower heliconia Golden Torch submitted to mineral, organic and organic-mineral fertilization. The following variables were evaluated: number of the offshoots per plant, number of flowers stalk per bunch, length and diameter of the flowers stalk, length of the bracts, number of the leaves and leaf area per plant. The results showed that organic and organic-mineral fertilization promoted the highest harvest of flower stalks. The organic fertilization promoted higher yield of the production components in comparison to control and the organic-mineral fertilization treatments. The association of mineral fertilized and organic manure improved the fertilization practice in this crop.

Influence of water content and soil compaction on the potassium diffusion flow into soil

Potassium, as well as phosphorus, is transported by diffusion to the absortion zone. Eight levels of soil moisture (10, 20, 40, 60, 70, 80, 90 and 100%), defined as a percentage of the soil total porosity, were combined with two soil densities (the natural bulk density and a compaction corresponding to 30% above the natural bulk density) in three soil samples, varying in their physiochemical characteristics, and the potassium diffusive flux (KDF) was measured using resin strips. To determine KDF, the resin strips were placed on the top of the soil samples. Chambers made of PVC rings (10 cm in diameter and 5 cm high) were used, which were placed in plastic bags to avoid evaporation, and maintained under controlled temperature (25 ± 3 oC) for 15 days. After this period of time the resin strips were removed, washed with destilled water, and K extracted by a NH4Cl 0.8 mol L-1 + HCl 0.2 mol L-1 solution. KDF increased with soil moisture levels and decreased with compaction. When the soil was compacted, a linear relation between moisture levels and KDF was observed. However, for non-compacted soils, this relation was observed only for the sandy soil, not for the more clayey ones. It was concluded that the linear relation between KDF and soil moisture content, as predicted by the diffusion equation, is not universal and depends upon the range of soil moistures under consideration.