Parcelamento da adubação nitrogenada na cultura do milho irrigado em sistema plantio direto

The purpose of this study was to evaluate the best time for application of N for an irrigated corn crop in a no-tillage system in the State of Alagoas. Three corn hybrids were used (TORK, FORT and BRS-3003) with four application times (days after sowing - DAS) for fertilizing with nitrogen as top dressing, consisting of the following treatments: 1) 120 kg ha-1 at 15 DAS, 2) 60 kg ha-1 at 15 DAS and 60 kg ha-1 at 30 DAS, 3) 120 kg ha-1 at 30 DAS, 4) 60 kg ha-1 at 30 DAS and 60 kg ha -1 at 45 DAS and 5) control treatment without N fertilization. The experimental design was in randomized blocks with four replications in a subdivided plot scheme. The components of the production studied were: final population of plants ha-1, numbers of corn ears ha-1 length of corn ears and number of rows of grains of corn and mass of 1000 grains. The productivities of grains obtained did not present significant differences among the treatments that received fertilization with nitrogen, independent of the time of application and number of split applications. It is concluded that in the notillage system in Alagoas spliting the manuring with nitrogen (top dressing) is not necessary.

Relação entre a adubação nitrogenada e as condições hídricas do solo para um cafezal de Piracicaba, SP

Although the management of the coffee crop is well established in Brazil, there is still room for its improvement in relation natural resources available in each region, aiming the increase in productivity. Here are presented results regarding the fate of the fertilizer nitrogen (N) applied to a coffee plantation related to the prevailing soil water conditions. Soil water balances are discussed, which allowed evaluation of the root distribution, determinations of the crop coefficient and of the soil water conditions during the development of the crop. Approximately, 60% of the root system was distributed in the 0-0.3 m soil layer and the average crop coefficient was 1.1 for 3 to 5 year old plants. Using an N label, the 15N, it was possible to study the distribution of N in the plant and in the soil and establishes general N balances, which also include losses like leaching and volatilization. After two years of ammonium sulfate application, at rates of 280 (1st year) and 350 (2nd year) kg.ha-1 of N, in four equal application performed during the period of positive growth rate, the recuperation of fertilizer N were 19.1% by the aerial plant part and 9.4% by the roots, 12.6% remained in the soil and 11.2% in the litter; 0.9% was lost by volatilization and 2.3% by leaching; 26.3% was exported through harvesting and 18.2% remained in non evaluated compartments. From the applied 630 kg.ha -1 of N during the two years, 180 kg.ha -1 of N were found in the plant (shoot and root), which corresponds to 28.6%; 150 kg.ha -1 of N remained available for the next years(soil and litter), and only 20 kg.ha -1 of N were effectively lost (volatilization and leaching).

Produção de Brachiaria brizantha e Panicum maximum com milho e adubação nitrogenada

In places characterized with high temperatures and rain occurrence in great intensity in the summer, but with dry winter, the major limitations for the sustainability of no tillage systems are low production of straw during fall-spring period and the fast decomposition during the rain season. To try to solve the problem, intercropped cultures of grains with forage species has presented reliable results; because offer vegetal covering to the next sowing, giving sustainability to the no tillage system. However, being a recent technology, its needed further studies in different areas involved for this system of production. Thus, this study had the objective 1) to evaluate the production of corn grain at different periods of intercropping with Brachiaria brizantha and Panicum maximum in no tillage system, and 2) aimed to evaluate the performance of forage at different periods of intercropping and the responses to nitrogen fertilization after the harvest of the corn, assessing mass productivity and quality. The experiment was carried out at the Lageado experimental farm, School of Agricultural Sciences, Botucatu campus belonged to São Paulo State University (UNESP) in structuralized Red Nitosol (Afisol). The experimental design was randomized blocks with four replications. The treatments were composed for four systems of no tillage involving corn: 1) single corn; 2) corn with Brachiaria brizantha cv. Marandu intercropped in the sowing; 3) corn with Brachiaria brizantha cv. Marandu intercropped with the fertilization of covering; 4) corn with Panicum maximum cv. Mombaça intercropped in the sowing and 5) corn with Panicum maximum cv. Mombaça intercropped with the fertilization of covering. After the harvest of the corn, it was applied, in equivalent quantities of nitrogen, ammonium nitrate in covering in doses of 0, 30, 60 and 120 kg ha-1, determining the forage mass productivity and quality. The simultaneous tillage of corn with P. maximum cv. Mombaça in the sowing compromises the grain productivity. When sowed in intercropping, B. brizantha presents a fiber concentration reduction and greater TDN concentration during the fall-spring period. Regarding benefits of intercropped cultures seeking to use in systems of production like agriculture-pasture integration, the best intercropping to be utilized is corn sown simultaneously with B. brizantha cv. Marandu.

Custos e rentabilidade do milho em função do manejo do solo e da adubação nitrogenada

Agronomic practices that help farmers to raise yield and reduce costs must be studied to ensure agricultural sustainability. Thus, the objective of this study was to analyze economically the effect of soil management and nitrogen fertilization in maize crops. Treatments consisted of a combination of 3 soil management techniques (plow harrows + floating harrows, chisel + floating harrows, and no-tillage), 5 periods of nitrogen fertilization (control - 0 kg ha -1 N; 120 kg ha -1 after sowing (S); 120 kg ha -1 in the V 6 stage; 30 kg ha -1 (S) + 90 kg ha -1 in V 6; 30 kg ha -1 (S) + 45 kg ha -1 in V 4 + 45 kg ha -1 in V 8 The total operating cost (TOC), gross revenue (GR), operating profit (OP), profitability index (PI), break-even yield, and break-even price were estimated. It was concluded that the no-tillage system, after 11 years of management, associated with nitrogen fertilization promotes positive PI and OP, being useful to farmers.

Proteína e qualidade de sementes de feijão (Phaseolus vulgaris L.) em função da adubação nitrogenada em plantio direto

Nitrogen limitation in the common bean (Phaseolus vulgaris L.) produces reduced productivity and seeds with low protein content and physiological quality. We assessed the effects of nitrogen fertilizer side dressing on the protein content and physiological quality of the seeds of P. vulgaris L. cultivars (cv.) IPR Juriti and Pérola grown in plots (soil type = Dystrophic Red Latosol) using a no-tillage system under a thick mulch of millet residues at the Experimental Station of UNESP-Ilha Solteira campus, located in Selvíria, MS (Köppen climate type = Aw) during autumn (March/June) and winter (June/September) 2005. For each cultivar, a randomized block experimental design was used with four replicates and factorially arranged treatments equivalent to 0, 30, 60, 90 and 120 kg.ha-1 added nitrogen (as urea, containing 45% of N) applied as a side dressing during the V4-3 and V4-6 phenological stage corresponding to the 3rd and 6th completely opened trifoliolate leaf on the main stem. Supplementation with up to 120 kg.ha-1 nitrogen promoted a greater increase in crude protein at V4-3 (unsupplemented = 17.6% and 16.3%; 120 kg.ha-1 N = 24.1% and 22.3% for cv. IPR Juriti and Pérola, respectively) than at V4-6 (unsupplemented = 19.2% and 18.3%; 120 kg.ha-1 N = 21.3% and 20.3% for cv. IPR Juriti and Pérola, respectively). About 90% of the crude protein from cv. IPR Juriti was composed of soluble protein compared to 72% for the cv. Pérola. Albumins and globulins represented about 80% of the soluble protein and prolamins were lower at 0.6%. In conclusion, nitrogen fertilization up to 120 kg.ha-1 applied as a side dressing at the V4-3 phenological stage in no-tillage under a thick mulch of millet promoted a greater increase of crude protein in common bean seeds than at the V4-6 stage. The highest accumulation of soluble protein occurred at 90 kg.ha-1 applied nitrogen without having a significant influence on the physiological quality of the seeds.

Use of modified atmosphere to extend shelf life of fresh-cut carambola (Averrhoa carambola L. cv. Fwang Tung)

Fresh-cut fruit products, including carambola (Averrhoa carambola L.) have limited marketability due to cut surface browning attributed to oxidation of phenolic compounds by enzymes such as polyphenol oxidase (PPO). The objective of this study was to evaluate postharvest changes of carambola slices in three different packagings. Carambola fruit (cv. Fwang Tung) were picked from the orchard of Estação Experimental de Citricultura de Bebedouro at mature-green stage. Fruit were washed, dipped in NaOCl solution (200 mg.L -1 for 5 minutes), and stored overnight at 10°C. Fruit were manually sliced into pieces of approximately 1 cm. Slices were rinsed with NaOCl solution at 20 mg.L-1, drained for 3 minutes, and packaged in polyethylene terephthalate (PET) trays (Neoform N94); polystyrene trays covered with PVC 0.017 mm (Vitafilm - Goodyear); and vacuum sealed polyolefin bags (PLO, Cryovac PD900). The packages were stored at 6.8°C and 90%RH for 12 days and samples taken every 4 days. PET trays and PVC film did not significantly modify internal atmosphere and the high water permeability of PVC led to more rapid slice desiccation. PPO activity was lower when slices were packaged in PLO vacuum sealed bags, which reduced discolouration and led to better appearance maintenance for up to 12 days.

Produtividade de cana-de-açúcar sob adubação com torta de filtro enriquecida com fosfato solúvel

Phosphorus is considered an essential element for plants and it is found in small amounts in Brazilian soils. The filter cake residue, composed of a mixture of bagasse and decanting sludge, has high levels of organic matter, phosphorus and calcium. The phosphorus present in the filter cake is organic, and its release, as it happens to the nitrogen, occurs gradually by mineralization and by microorganisms attack in the soil. This study aimed to evaluate sugarcane vegetative growth and yield under fertilization with filter cake enriched with soluble phosphate. The experiment was carried out in Presidente Prudente, São Paulo State, Brazil, by using a randomized complete block design, in a 5x4 factorial scheme, where the first factor consisted of filter cake doses (0 t ha-1, 0.5 t ha-1, 1.0 t ha-1, 2.0 t ha-1, and 4.0 t ha-1) and the second of phosphorus fertilizer doses (0 kg ha-1, 50 kg ha -1, 100 kg ha-1, and 200 kg ha-1 of P 2O5), with 4 repetitions, totalizing 80 plots. The experiment evaluated the tiller number, at 30, 60, 90, and 120 days after planting, oBrix, and yield. The stalk yield and tillering were influenced by the filter cake rates applied to the soil. Filter cake doses and their combination with phosphate did not change the juice quality (Brix) at harvest.

Produção de rúcula e acúmulo de nitrato em função da adubação nitrogenada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Atributos químicos do solo sob plantio direto afetado por sistemas de culturas e fontes de adubação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da irrigação, da densidade de plantio e da adubação nitrogenada nas características morfogênicas, estruturais e de produção do capim-tanzânia

This experiment was carried out to evaluate canopy height of guinea grass with 95% of photosynthetic active radiation interception and quantify the nitrogen fertilization influence and plants' density on the morphogenesis and structural characteristics of Tanzania grass. Four doses of N (0, 80, 160 e 320 kg.ha -1), were arranged with three plant densities (9, 25 and 49 plants.m -2), according to 4 × 3 completely randomized design, with three repetitions. Total dry matter (DM) accumulation throughout the experimental period was influenced by nitrogen fertilization and plants' density. In the rainy period, the higher nitrogen fertilization decreased the harvesting intervals, and consequently, increased the number of harvests. The rate of leaf appearance and the phyllochron were influenced only under nitrogen fertilization in the transition period of rainy and dry weather. Tanzania grass canopy height under 95% of light interception was positively influenced because of the plant densities in rainy period and transition period between rainy/drought and drought. Tanzania grass height under 95% of light interception presented variations along the evaluations and the values were higher (near 70 cm) in the rainy period, followed by transition period rain/drought and drought. © 2011 Sociedade Brasileira de Zootecnia.

Efeito da antecipação da adubação nitrogenada na cultura do milho em sistema plantio direto

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preparados homeopáticos e adubação verde no controle de Cyperus rotundus L.

In the search for natural herbicides for the management of the Cyperus rotundus L. in crops this work evaluated alternative methods to control weed, aiming at sustainability. The experiment was carried out in pots, in a greenhouse at the Experimental Station Lageado, FCA-UNESP-Botucatu, from april to may 2008. The experimental design was entirely randomized, with three repetitions, and treatments consisted of aqueous extract of Stilozobium aterrimum Piper & Tracy, residue of the green manure on the soil surface and incorporated into soil, homeopathic preparations and control treatment with no applications. The aqueous extract of green manure and homeophathic preparation provided both reduction in the development of C. rotundus. The fresh weight of the aerial part of S. aterrimun stimulated the growth of the weed both as cover and incorporated into the soil.

Adubação nitrogenada e critérios de amostragem foliar para a cultura da batata

The present study aimed to determine which leave will be displayed and the time of collection of this leave. The treatments consisted on five doses of nitrogen, four times for collection sampling and three types of leaves, arranged in a randomized block design with three repetitions, totalizing one hundred and forty-four experimental units. The leaves collections took place every fifteen days at thirty, forty-five, sixty and seventy five days after budbreak (DAB), collecting the laminated / compound young leaf (first leave), newly mature (second leave) and the mature leave (third leave) from the set of terminal leaflets. For this was installed an experiment with the culture of potato (cv. Atlantic), in Barretos/SP, the period of march the june of 2010. According to this data collected in this study, the best time for collecting the leaves is at 30 days after the budbreak of the potato cultivation containing nitrogen concentrations in the leaves minus heterogeneous of plants from a fraction to another and with values R2 = 0.98 being higher to the all times of harvests. To the diagnostic leaf, the highest determination coefficient was observed in the newly mature (second leaf) with R2 = 0.98. It can be observed that the highest levels of nitrogen were found on the first leaf (39.01 kg-1). Nevertheless, the values were very heterogeneous and did not fit the curve being the second leave (newly mature) the one that best represents the nutritional status of the plant. Therefore the recommendation for nutritional diagnosis will collect the recently matured leaves (2nd leaf) 30 days after budbreak.

Plantas de cobertura e adubação nitrogenada na cultura do algodoeiro

The fiber quality, productivity and favorable climate are considered key points for the development of the cotton crop in the Brazilian Cerrado. This study aimed to evaluate the effect of cover crops and N application in presowing on the cotton crop growth and yield. The experimental design was randomized blocks, consisting of a - three cover crops (radish, white oat and black oat) implanted during the winter period, b - four nitrogen levels (0, 30, 60 and 90 kg ha-1 of N) applied to the millet residues and before cotton sowing. In April 2008, evaluations were realized of plant development and also harvesting was performed of experimental plots of cotton plants. The results showed that the radish provides increased length of branches and cotton bolls of cotton crop, without yield increase, and the use of increasing doses of N up to 90 kg ha-1 decreased the amount of carimã per plant, increasing the number of reproductive branches and cotton yield.

Características morfogênicas e estruturais de híbridos de sorgo submetidos a adubação nitrogenada

The effect of two topdressing nitrogen doses was evaluated on the morphogenetic and structural characteristics of sorghum hybrids (Sorghum bicolor (L.) Moench) BRS 801 and 0734006, cultivated in vases in open-air conditions. A completely randomized design was used with four treatments arranged in factorial outline 2x2 (two sorghum hybrids and two nitrogen doses, 50 and 100 kg ha-1), with eight replications per treatment. There was a significant effect of interaction hybrid x fertilization on the leaf appearance rate, the hybrid BRS 801 being more responsive to the increased nitrogen dose. The phyllochron, the total number of leaves and leaf elongation rate, were influenced both by nitrogen doses and by hybrids. The leaf senescence rate was not influenced by factors fertilization and hybrids. These variations in morphogenetic and structural characteristics between the hybrids and/or nitrogen doses, probably indicate that hybrids respond in a different way to topdressing.