Culturas de cobertura, doses de nitrogênio e residual da aplicação de calcário: características químicas do solo, estado nutricional e características agronômicas do milho

Pós-graduação em Agronomia - FEIS

Dose, parcelamento e modo de aplicação de nitrogênio em atributos nutricionais, agronômicos e tecnológicos de cultivares de sorgo sacarino

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Características agronômicas do trigo em função de Azospirillum brasilense, ácidos húmicos e nitrogênio em casa de vegetação

The objective of this study was to investigate the effect of the combined use of Azospirillum brasilense, humic acid and different levels of nitrogen on agronomic characteristics of wheat under greenhouse conditions. The experiments were installed on May 21, 2011 and proceeded to harvest on September 13, 2011. The experimental design was a randomized complete block in a 4 x 4 factorial design with four replications. The first factor relates to the combination of strain Ab-V5 of A. brasilense with humic acids, with the following treatments: control, Ab-V5, humic acid and Ab-V5 + humic acid and the second factor refers to nitrogen levels (0, 30, 60 and 90 kg ha-1 N). Most variables in the analysis had a positive linear effect of treatments depending on nitrogen fertilization, and only for variable weight of hundred grains, the negative effect was linear. There were no significant differences between the variances in grain production. It was concluded that the combined use of Ab-V5 + humic acid promotes the production mainly of dry leaves and are not responsive to nitrogen fertilizer for other productive components under study, as well as grain yield.

Influência da adubação com nitrogênio e fósforo na produção de Jambu, Acmella oleracea (L) R.K. Jansen

The objective of this work was to evaluate the influence of the use of nitrogen and phosphorus in the culture of jambu. The experiment was initiated at the experimental farm of the agency APTA Polo Vale do Ribeira, using the Nazaré cultivar. The experimental design was complete randomized with fourlevelsof nitrogen (0, 37.5, 75 and 112.5 kg ha-1 N) and phosphorus (0, 75, 150 and 300 Kg ha-1P2O5),and four reapplications. After soil preparation, liming and fertilization, seedlings of jambu were transplanted at a spacing of 0.50 x 0.5 m. The experimental plot was 1.0 x 1.0 m. Fresh and dry mass of leaves and flowers and number of flowers were analyzed. The production of fresh and dry leaves and flowers were influenced by fertilization. Thelevelsof nitrogen affected the outcome, as theyprovided a linear increase in all variables, and the phosphorus level of 75 kgha-1 P2O5 caused the highest average production in the number of flowers and in the fresh and dried mass of flowers.

Coberturas vegetais e doses de nitrogênio em trigo sob sistema plantio direto

The application of conservation practices in production systems is essential to the sustainability of the agricultural production capacity. The use of different cover crops can reduce the need of topdressing nitrogen fertilizers in wheat crops. This study aimed at evaluating the influence of cover crops residues (millet, sunn hemp, pigeon pea, millet + sunn hemp, millet + pigeon pea and fallow ground), grown previously to the summer crop (rice), and topdressing nitrogen doses (0 kg ha-1, 25 kg ha-1, 50 kg ha-1, 75 kg ha-1, 100 kg ha-1 and 125 kg ha-1), in the development and yield of wheat under no-tillage system. The experiment was carried out in Selvíria, Mato Grosso do Sul State, Brazil, in a Red Oxisol, in 2009/2010 and 2010/2011. The experimental design was randomized blocks, in a 6x6 factorial scheme. The cover crops developed during August/October (2009/2010) and September/November (2010/2011), previously to the summer crop, with the chemical desiccation performed respectively at 73 and 55 days after sowing. The wheat (winter) was sown in May, in both periods, and harvested at 113 (2009/2010) and 106 (2010/2011) days after emergence. The cover crops residues of pigeon pea, sunn hemp and millet + sunn hemp, preceding wheat, provided higher wheat yields, relatively to the fallow ground. The wheat yield showed a quadratic response to the increase in the nitrogen availability, reaching higher yields with the nitrogen doses estimated in 113 kg ha-1 (2010) and 98 kg ha-1 (2011).

Produtividade do milho em condições de diferentes manejos do solo e de doses de nitrogênio

Research has been conducted to identify the best nitrogen (N) rate for maize in most diverse types of soil management. However, there is no agreement on the results, once the dynamic of N is influenced by soil management and cover crops. This study evaluated dry mass production and nutrient uptake by cover crops, agronomic parameters and grain yield of maize in response to soil management and N rates. Field trials were carried out in Selvíria, Mato Grosso do Sul State, Brazil, in the growing seasons of 2009/2010 and 2010/2011, on a clayey Rhodic Haplustox (20º 20' S and 51º 24' W, 340 m asl). Thirty-six treatments were established with four replications, in a randomized blocks design, with the combination of cover crops (millet, Crotalaria juncea and millet + Crotalaria juncea), soil management systems (tillage with chisel plow + lightweight disking, heavy disking + lightweight disking, and no-tillage) and topdressing N rates (0, 60, 90 e 120 kg ha-1 - urea as source). Maize hybrid DKB 350 YG® was used and N applied at stage V5 (fifth expanded leaf). A linear increase with the increase of N rates was observed for chlorophyll leaf index, leaf N content, ear length and diameter, and grain weight and yield. Previously grown sunn hemp and millet + sunn hemp grown, associated with 120 kg ha-1 N for maize, induced a higher grain yield after two growing seasons.

Coberturas vegetais, manejo do solo, doses de nitrogênio e seus efeitos na nutrição mineral e nos atributos agronômicos do milho

Research has investigated the best nitrogen rate for maize under the most diverse types of soil management. The aim of this study was to evaluate the influence of cover crops, soil management and topdressed N rates on the dry matter production, nutritional status, plant lodging, plant height and first-ear insertion of maize. Field experiments were carried out in Selvíria, Mato Grosso do Sul State, Brazil, in the growing seasons of 2009/2010 and 2010/2011, on a clayey Rhodic Haplustox (20º 20' S and 51º 24' W, at 340 m asl). Thirty-six treatments were established with four replications, in a randomized blocks design, to test combinations of cover crops (millet, Crotalaria juncea and millet + Crotalaria juncea), soil management (tillage with chisel plow + lightweight disking, heavy disking + lightweight disking, and no-tillage system) and N rates (0, 60, 90 e 120 kg ha-1 - urea as source). The maize hybrid DKB 350 YG® was used and topdressing N applied at stage V5 (fifth expanded leaf). Previously grown sunn hemp and millet + sunn hemp resulted in a higher shoot dry matter, P leaf content and total N, P and K uptake. In the no-tillage system, the initial and final population and shoot dry were highest, and first-ear insertion and plant height lower. The application of 120 kg ha-1 topdressed N increased the P leaf content, N and P in the entire plant, shoot dry matter, total N, P and K uptake, plant height, and the first-ear insertion of maize.

Da escassez ao estresse do planeta: um século de mudanças no ciclo do nitrogênio

Heavy metals and pesticides are usually associated with the main problems humankind has created in the natural environment. However, compounds with characteristics of essential macronutrients are causing serious environmental changes that could intensify, compromising the diversity of life on the planet. This is the case of nitrogen compounds, produced by industrial processes for use in intensive agriculture in addition to those unwittingly produced from human activities, available in excess in the environment. These compounds warrant greater attention from researchers in various fields of knowledge and public agencies for environmental control, toward minimizing their availability in the environment, thereby returning conditions closer to the natural environmental balance of the planet.

Descrição do potencial de retenção de nitrogênio em frangas de postura por diferentes metodologias: mínima retenção

The objectives of this study were to describe the potential for nitrogen retention by two techniques: comparative slaughter and nitrogen balance; compare the adjusted models for each technique and estimate the maintenance requirement for pullets. Assays were performed during 14 to 28, 56-70 and 98 to 112 days of age, using 168 pullets. The design was completely randomized with seven treatments and eight replications. Treatments consisted of protein levels ranging from 75 to 435gkg-1 of dry matter. The variables were collected by comparative slaughter and nitrogen ingested and deposited in nitrogen balance technique intake and nitrogen excretion. The intercept of the exponential relationship between ingested and excreted nitrogen was considered a requirement for maintenance. The adjusted models were compared by using the maximum likelihood ratio. The techniques described differently compared the requirement for maintenance of nitrogen. For comparative slaughter requiring maintenance was estimated at 342, 372 and 543mg/kgPC0,67 and for nitrogen balance was 342, 225 and 284mg/kgPC0,67 for the period of 14 to 28, 56-70 and 98 to 112 days of age, respectively.

Potencial de produção de gás metano e dióxido de carbono in vitro dos ingredientes utilizados em dietas para ovinos

This study aimed to evaluate the potential of CH4 and CO2 in vitro production of soybean hulls, sunflower meal, corn, citrus pulp and corn silage. Four rumen-cannulated sheep were fed diets containing the evaluated ingredients at 40:60 forage:concentrate ratio. The gases produced by samples incubation were measured by injection into a gas chromatograph equipped with flame ionization detector. The experimental design was completely randomized with repeated measures, with three replicates for each evaluated food at four different periods. Under the experimental conditions, we verified different potential gas production among the ingredients. The citrus pulp meal was the ingredient with the greatest potential for CO2production. Corn silage and soybean hulls showed the greatest potential while citrus pulp and sunflower meal showed the least potential for CH4 production, when expressed in mL/g of degraded dry matter; therefore, they can be considered, among the evaluated ingredients, those with the lowest environmental impact.

Descrição do potencial de retenção de nitrogênio em frangas de postura por diferentes metodologias: máxima deposição e estimativas da ingestão de metionina+cistina

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Produção de chicória em função de doses de nitrogênio e potássio aplicadas na fase de mudas

Considering there are few researches about the influence of seedlings fertilization on yield, this work was carried out in order to evaluate the effect of rates of nitrogen and potassium, applied by fertirrigation, in endive seedlings on yield. Two experiments were carried out, the first with four treatments, varying nitrogen rates, and the second with four potassium rates. In both, experimental design was randomized blocks, with four replications. In the first experiment, we utilized ammonium nitrate, weekly, at rates 0; 40; 80 and 120 mg of N L-1, while in the second experiment we utilized potassium chloride, weekly, at rates 0; 70; 140 and 210 mg of K2O L-1. The evaluated characteristics at seedling stage were shoot height, number of leaves, fresh and dry shoot weight. At harvesting, we evaluated plant height, diameter, number of leaves and fresh weight. Potassium rates did not influence all characteristics, at seedling and at harvesting stages. For all seedling characteristics, there was linear increasing depending on nitrogen rates. But, for plant fresh weight, diameter and number of leaves at harvesting, the effect was quadratic. The highest fresh weight and number of leaves at harvesting were obtained with 90 mg of N L-1.

Extração e exportação de nutrientes pelo feijoeiro adubado com nitrogênio, em diferentes tempos de implantação do sistema plantio direto

Common bean grown in no-tillage (NT) systems has increased markedly in Brazil. Thus, to optimize the fertilizer recommendations, it is important to know the nutritional requirements of this crop when grown under new and established NT systems, which can change the nutrient availability and crop response to nitrogen (N) fertilization. The objective was to evaluate the extraction and exportation of nutrients by common bean as function of N fertilization on soil under new and established NT systems. The experiment was carried out in two agricultural years, on a Red Nitosol (Alfisol) in Botucatu, São Paulo State, Brazil. A randomized complete block design was used in a split-plot scheme with four replications. The plots consisted of areas under NT systems after different periods of adoption and the subplots of four forms of N application to common bean (T0: control, without nitrogen; T1: 60 kg ha-1 before sowing; T2: 60 kg ha-1 sidedressed at V4 stage; and T3: 60 kg ha-1 before sowing + 60 kg ha-1 sidedressed). The following properties were evaluated: shoot dry matter, nutrient concentration and accumulation in the shoot, grain yield, and nutrient concentration and exportation in the grains. The NT age did not affect common bean yield, nutrition and response to N management. Nitrogen application, especially before sowing, led to higher dry matter and nutrient accumulation by common bean. The nutrient concentration in grains was little influenced by N fertilization. Grain yield and nutrient exportation were highest after double N application (before sowing and sidedressed) or only sidedressed at V4.

Épocas de aplicação de nitrogênio em feijoeiro cultivado após milho solteiro ou consorciado com braquiária

The objective of this work was to evaluate the common bean response to N application timing, under no-tillage system, after single corn or intercropped with palisade grass. A randomized complete block experimental design was used in a split-plot arrangement, with four replicates. Plots consisted of: single corn crop or corn intercropped with palisade grass, in two summer cropping seasons precedent to common bean sowing. Subplots consisted of: 100 kg ha-1 N application in three times - before sowing, at sowing, and at side-dressing - and a control treatment without N application. Nitrogen fertilization on common bean increased leaf-N content, the number of pods per plant, and grain yield (33% in the average application timing), only in the cropping after single corn. By providing large mass production and by N cycling, the cultivation of palisade grass intercropped with corn reduced N requirement of common bean in succession, in comparison to previous sole corn cultivation. Early N application before or during common bean sowing time provides grain yield similar to the observed one in the side-dressing application.

Suscetibilidade à podridão negra e produtividade de brócolis em função de doses de nitrogênio e potássio

The purpose of this study was to investigate the influence of potassium and nitrogen on the severity of black rot and yield of head. The experiment was carried out in split plots with factorial subplots, in randomized blocks with four replications. In the plots we assessed the influence of inoculation (injured plants with distilled water and inoculated with Xanthomonas campestris pv. campestris) and in the subplots we evaluated the 4 x 4 factorial, potassium doses (0, 275, 550 and 825 kg ha-1) and nitrogen (0, 150, 300 and 450 kg ha-1). The hybrid Broccoli BRO68 was inoculated using the toothpick method at 64 days after sowing. We observed that potassium in the plant reduced the disease, but nitrogen increased disease. We estimated that the highest levels of potassum in the plant reduced the severity of the disease but lack or excess of nitrogen increased disease severity. The highest production of broccoli inflorescence was obtained at doses from 541 to 751 kg ha-1 of K2O and 286 to 328 kg ha-1 of N. However, when considering a balanced fertilization to obtain higher yield and size of inflorescences and greater resistance to black rot, the ideal doses are 283 kg ha-1 of N and 550 kg ha-1 of K2O.