Isoquantas de Produtividade da Cana-de-açúcar em Função de Níveis de Irrigação e Adubação Nitrogenada.

Um experimento de campo com diferentes níveis de irrigação e nitrogênio foi conduzido no Centro de Ciências Agrárias da Universidade Federal de Alagoas com o objetivo de determinar a função de produção e as isoquantas de produtividade agrícola da cana-de-açúcar com base nas lâminas de irrigação e doses de nitrogênio (N). A precipitação pluvial efetiva durante o ciclo de produção foi 1.037 mm e a lâmina de irrigação bruta máxima foi 873 mm. A produtividade agrícola ficou entre 118 e 188 Mg ha-1, média de 160 Mg ha-1. Na isoquanta da produtividade agrícola média da cana-de-açúcar, a taxa marginal de substituição de água por N é 0,36 kg mm-1 (na interseção das retas de 25 kg de N ha-1 e 760 mm de irrigação) e infinita (na interseção das retas de 125 kg de N ha-1 e 390 mm de irrigação). A quantidade de água e nitrogênio de menor custo para produzir 160 Mg ha-1 foi 390 mm de irrigação e 112 kg de N ha-1. A regressão polinomial de segundo grau apresentou ajuste médio (r2 = 62%) para a produtividade agrícola em relação às lâminas de irrigação e doses de nitrogênio. A resposta da cana-de-açúcar à adubação nitrogenada aumenta em proporção direta com disponibilidade hídrica do solo.

Decomposição da palhada de forrageiras em função da adubação nitrogenada após o consórcio com milho e produtividade da soja em sucessão

The objective of this study was to evaluate the straw decomposition of the Urochloa and Panicum after intercropped with corn and nitrogen fertilization, as well as, the agronomic performance of soybean in succession. The experiment was conducted in an Oxisol in Cerrado conditions under no-tillage eight years ago. After the corn harvest intercropped with grass and cutting of forage homogenization were applied N rates (0, 50, 100 and 200 kg ha-1 of N - urea source) in coverage. The plots consisted of Urochloa brizantha,Urochloa ruziziensis and Panicum maximum Tanzânia and Mombaça sown at the time of corn sowing and subplots composed by accumulated amounts of nitrogen applied in forage plants prior to the soybean cultivation (0, 250, 500 and 1000 kg ha-1 of N, after five cuts). The experimental design was a randomized block with four replications in a split plot. Soon after the last cut of the forage, proportionate amount of fresh mass of the species of each subplot was wrapped in nylon bags called Litter Bags, these being deposited in direct contact with the soil, to determine the time of decomposition of the dry mass during a period of 150 days. The nitrogen doses, as well as, the corn intercropped with forages (except with Mombaça) interfere similarly in the straw decomposition of forage and in the soybean yield in succession. All the consortiums of corn and nitrogen fertilization predecessors determined that, at 60 days after desiccation and cutting, still remained between 50 and 60% of the initial straw for no-tillage system.

Adubação nitrogenada em feijoeiro em sucessão a cultivo solteiro e consorciado de milho e Urochloa ruziziensis

The expansion of the no-tillage system, in Brazil, has increasingly diversified the ways in which the production methods are established and managed. This study aimed at evaluating the influence of preceding crops such as mayze and Urochloa ruziziensis, as well as their intercropping, in the presence and absence of seed inoculation with Azospirillum brasilense, and the cover nitrogen supplying on common bean development, production components and grain yield. The study was carried out in Selvíria, Mato Grosso do Sul State, Brazil, in the 2011/2012 crop season. The experimental design was randomized blocks, with four replications, in a 8x4 factorial scheme, with treatments consisting of a combination of cover crops (associations of mayze, U. ruziziensis and A. brasilense) and cover nitrogen doses on common bean (0 kg ha-1, 30 kg ha-1, 60 kg ha-1 and 90 kg ha-1). The preceding crops affected the common bean grain yield, with the mayze and Urochloa intercropping, both inoculated, being the best option. The initial common bean population was not affected by previous crops. The cover nitrogen application did not affect the common bean grain yield under winter irrigation, for the no-tillage system.

Adubação nitrogenada e aplicação de herbicidas como reguladores de crescimento em grama esmeralda

Pós-graduação em Agronomia - FEIS

Resposta de cultivares de feijão comum à adubação nitrogenada

Pós-graduação em Agronomia (Agricultura) - FCA

Estimativa da produtividade de trigo em função da adubação nitrogenada utilizando modelagem neuro fuzzy

Currently new techniques for data processing, such as neural networks, fuzzy logic and hybrid systems are used to develop predictive models of complex systems and to estimate the desired parameters. In this article the use of an adaptive neuro fuzzy inference system was investigated to estimate the productivity of wheat, using a database of combination of the following treatments: five N doses (0, 50, 100, 150 and 200 kg ha(-1)), three sources (Entec, ammonium sulfate and urea), two application times of N (at sowing or at side-dressing) and two wheat cultivars (IAC 370 and E21), that were evaluated during two years in Selviria, Mato Grosso do Sul, Brazil. Through the input and output data, the system of adaptive neuro fuzzy inference learns, and then can estimate a new value of wheat yield with different N doses. The productivity prediciton error of wheat in function of five N doses, using a neuro fuzzy system, was smaller than that one obtained with a quadratic approximation. The results show that the neuro fuzzy system is a viable prediction model for estimating the wheat yield in function of N doses.

Produtividade e qualidade de grãos de canola em função da adubação nitrogenada e sulfatada

The canola (Brassica napus, L.) cultivation was encouraged for grain and oil production at the 80's, and it is also considered a good option for crop rotation. The nitrogen is one of the most required nutrients by the plant to increase its production, while sulfur is essential to provide seed quality. Thus, the objective of this study was, at Cerrado region, evaluate the effects of nitrogen and sulfur fertilization at yield and contents of oil and crude protein in the grains. We also sought relate to grain yield the S content in the soil and concentrations of N and S in the diagnosis leaf. The experiment was conducted in Uberaba County, State of Minas Gerais, Brazil, in an Oxisol, utilizing the Hyola 401 hybrid. The treatments consisted in a factorial scheme 5 x 4 (five N rates: 0, 60, 100, 140 and 180 kg ha(-1) and; four S rates: 0, 15, 30 and 60 kg ha(-1)) in a randomized blocks design, with four replicates. The nitrogen and sulfur fertilization increased canola grain yield, without significantly alter contents of oil and crude protein. Rates higher than to 140 kg ha(-1) of N and 15 kg ha(-1) of S provided grain yield above 1100 kg ha(-1). Plots with yield higher than to 1000 kg ha(-1) presented foliar concentration of N above 52 g kg(-1). The highest S content was observed at the 0.15-0.30 m layer, proving the sulfate anion mobility. The lowest grain yield were observed when the S content in the soil at this layer were less than 4 mg dm(-3). The N concentrations in the diagnostic leaf and S-SO4-2 content in the 0.15-0.30 m layer correlated positively with crop yield.

Acúmulo de macronutrientes e decomposição da palhada de braquiárias em razão da adubação nitrogenada durante e após o consórcio com a cultura do milho

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

Adubação nitrogenada em genótipos de soja associada à inoculação em semeadura direta no cerrado

Pós-graduação em Agronomia - FEIS

Adubação nitrogenada na cultura do milho com ureia revestida por diferentes fontes de polímeros

In view of theoretic increase in efficiency of nitrogen fertilizers for controlled release, this study aimed to evaluate the effect of nitrogen, using conventional urea and ureas coated by different polymers, in the leaf N content, leaf chlorophyll index, components production and grain yield of irrigated corn in growing season and second crop in the savannah region. The experiments were conducted at experimental area belonging to UNESP - Ilha Solteira, located in Selviria - MS in a dystrophic Red Latosol (Haplustox), clayey texture. The statistical design was randomized blocks, with four repetitions, in a 4 x 4 factorial arrangement, being four nitrogen doses (0, 40, 80 and 120 kg ha(-1)) applied at sidedressing and four urea sources (a conventional urea and three coated with polymers in different compositions and concentrations). The coated ureas are not efficient under the soil and climate conditions studied of the savanna, because they provided results similar to the conventional urea for the production components and grain yield of corn in the first and second crop. The increment of nitrogen doses increase linearly the leaf N content and grain yield of corn in the first and second crop.

Adubação nitrogenada no feijoeiro após palhada de milho e braquiária no plantio direto

The present study was carried out to evaluate the agronomic and technological performance of common-bean crop following three straw mulch production system (sole corn, corn-Urochloa ruziziensis inter-crop and sole U. ruziziensis) and topdressing nitrogen fertilization (0, 40, 80, 120 and 160 kg ha(-1) of N) in the fourth year after the no-tillage system implementation. A randomized block design, in a splitplot array, with three replications was used. The use of U. ruziziensis intercropped with maize allowed a greater straw mulch formation and a more adequate coverage of the soil surface aiming the beans cultivation in succession. The nitrogen fertilization influenced the common-bean productivity in succession to U. ruziziensis unique and maize intercropped with U. ruziziensis. The common-bean crop in succession to the straw mulch production system with U. ruziziensis allowed higher grain production and sieve yield. The grain cooking time decreased due to the rates of N used in the dry bean crop in succession of maize exclusive.

Manejo da adubação nitrogenada na cultura do milho pelo uso da inoculação com azospirillum brasilense em consórcio com capim xaraés

Pós-graduação em Agronomia - FEIS

Critérios para o manejo da adubação nitrogenada na cultura do feijão utilizando clorofilômetro portátil

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

Adubação nitrogenada para consórcio de alface e rúcula

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

Inoculação de sementes com Azospirillum brasilense e Rhizobium tropici e adubação nitrogenada em cobertura em feijoeiro de inverno irrigado em sistema plantio direto

Pós-graduação em Agronomia - FEIS