Henrique Pereira dos Santos

Efeitos de sistemas de produção de grãos envolvendo pastagens sob plantio direto nos atributos físicos de solo e na produtividade

Ley forming modifier soil structure, which, in turn, effects soil physical characteristics in the upper layer. The objective of this study was to evaluate soil physical attributes and grain yield in a typical dystrophic Red Latosol (Typic Haplorthox) located in Passo Fundo county (RS), Brazil, after eight years of mixed production cultivation (1993 to 2000). The effects of production systems integrating grain production with winter annual and perennial pastures under no-tillage were assessed. Four mixed production systems were evaluated: system I (wheat/soybean, white oat/soybean, and common vetch/corn); system II (wheat/soybean, white oat/soybean, and grazed black oat + grazed common vetch/corn); system III [perennial cool season pastures (fescue + white clover + red clover + birdsfoot trefoil)]; and system IV [perennial warm season pastures (bahiagrass + black oat + rye grass + white clover + red clover + birdsfoot trefoil)]. System V (alfalfa as hay crop) was established in an adjacent area in 1994. The areas under systems III, IV, and V returned to system I after the 1996 summer. The treatments were arranged in a randomized complete block design, with four replicates. As a control, physical soil parameter were evaluated in samples of a subtropical forest fragment adjacent to the experiment. Soil bulk density values were lower in the top layer (0-5 cm) than in the deeper layer (10-15 cm), while the reverse was observed for the total porosity and macroporosity. Systems I, II, III, and IV showed higher bulk density values and lower total porosity and macroporosity values in the surface layer (0-5 cm). System V and subtropical forest presented low bulk density and high total porosity and macroporosity values compared to the other treatments. It was observed no differences between physical attributes of integrated and non-integrated crop and livestock systems. No significant correlation was verified between crop yields and physical soil attributes, with exception of the soil macroporosity under soybean in the 0-5 cm layer.

Disponibilidade de nutrientes e teor de matéria orgânica em funçäo de sistemas de cultivo e de manejo de solo

Cropping systems and soil managment can change soil chemical properties. Soil fertility characteriscs were assessed after eight years (1985 to 1993) on a typical dystrophic red latosol located in Passo Fundo, State of Rio Grande do Sul, Brazil. Four soil management systems - 1) no-tillage, 2) minimum tillage, 3) conventional tillage using a disk plow plus disk harrow, and 4) conventional tillage using a moldboard plow plus disk harrow - and three cropping systems [I (wheat/soybean), II (wheat/soybean and common vetch/corn), and III (wheat/soybean, common vetch/corn and white oat/soybean)] were evaluated. A randomized complete block design, with split-plots and three replicates, was used. The main field plots (4 x 90m) were formed by soil management systems, while the subplots (4 x 10m) consisted of crop systems. The pH and concentration of exchangeable Al, exchangeable Ca + Mg, soil organic matter, extractable P, and exchangeable K were affected by soil management and cropping systems. Higher contents of soil organic matter, extractable P, and exchangeable K were observed in the 0-5cm layer for the conservation tillage systems (minimum tillage and no-tillage), as compared to the conventional tillage systems (disk plow and moldboard plow). The values of soil organic matter, P, and K were higher in the 0-5 cm layer, when compared to the ones observed in the 15-20cm layer, in all soil management and cropping systems.

Evolução tecnológica e arranjos produtivos de sistemas de integração lavoura-pecuária-floresta no Brasil

Evolucao tecnologica dos sistemas de integracao lavoura-pecuaria-floresta. Contribuicao do sistemas de integracao lavoura-pecuaria-floresta para a sustentabilidade da agropecuaria. Modalidades dos sistemas de integracao lavoura-pecuaria-floresta. Arranjos regionais de sistemas de integracao lavoura-pecuaria-floresta. Contribuicao da integracao lavoura-pecuaria-floresta para o sequestro de carbono e a reducao da emissao de gases de efeito estufa. Desafios e perspectivas para pesquisa, desenvolvimento e inovacao em integracao lavoura-pecuaria-floresta.

Lucratividade e risco de sistemas de produção de grãos combinados com pastagens de inverno

n†The objective of this work was to evaluate the profitability and risk of grain production systems combined with annual winter pastures, under no-tillage system. The experiment was carried out in Passo Fundo, RS, Brazil, in a†six-year period (1990-1995). The systems were: system†I (wheat/ soybean, grazed black oats/soybean, and grazed black oats/soybean); system†II (wheat/soybean and grazed black oats†+ grazed common vetch/corn); system†III (wheat/soybean, grazed black oats†+ grazed common vetch/soybean, and grazed black oats†+ grazed common vetch/corn); and system†IV (wheat/ soybean, white oats/soybean, and white oats/soybean). An†experimental design in blocks at random, with three replications and plots with 500†m 2 , was used. Three types of analysis were applied to the net return of systems: mean-variance analysis, distribution of accumulated probability, and stochastic domi- nance. When mean-variance analysis was used no significant differences were observed in the systems studied. By†the distribution of accumulated probability, the selection of an alternative depends solely and exclusively on the level of risk chosen by the decision-maker. By†the stochastic dominance method, system†II showed to be the best production alternative to be offered to farmers from both profit and lower risk standpoints.

INFLUÊNCIA DE CULTURAS DE INVERNO SOBRE O RENDIMENTO DE GRÃOS DE SOJA CULTIVADA EM SISTEMAS DE ROTAÇÃO DE CULTURAS

Different preceding crops on the yield and height of soybean plants was assessed during nine years at EMBRAPA-Centro Nacional de Pesquisa de Trigo (CNPT), in Passo Fundo, RS, Brazil. The treatments consisted of seven crop systems, and soybean was sown in succession to white oat, black oat, flax, and wheat. Two plots were added in 1990; one to complement system II and the other as winter fallow preceding soybean (system VII). Winter crops were set up using conventional soil preparation, and summer crops were sown under no-tillage. An experimental design of blocks at random, with three replications and plots totalling 30m2, was used. The grown soybean after flax, in the mean of the period 1987 to 1989, in systems IV and VI showed lower plant on height and lower yield. No significant differences were found on the evoluated preceding crops on the yield over the periods 1990 to 1992 and 1993 to 1995. The grown soybean after white oat, black oat or wheat may be included in the different systems studied without any adverse effect.

Efeito de pastagens de inverno e de verão em características físicas de solo sob plantio direto

Soil physical characteristics were evaluated, after seven years (1995 to 2001), on a typical Dystrophic Red Latosol located in Coxilha, State of Rio Grande do Sul, Brazil. Six systems integrating crop production with livestock and a subtropical forest were evaluated. Both winter and summer crops were seeded under no-tillage. Cropping systems and soil of different sampling depths were compared using the contrast procedure. In the I and II sistems and in the forest, the soil density and the resistance to penetration increased in the top layer (0-0,05m) concerning the deeper layer (0,10-0,15m). In the II system, total porosity and microporosity decreased in the surface. In the subtropical forest, the some was observed in relation to total porosity and microporosity. The forest showed decrease on soil density and resistance to penetration, compared to most crop systems studied, from 0-0,05m layer to 0,100,15m layer. Soil degradation in the systems could not be considered severe.

Yield and nutritive value of dual purpose winter cereals: green forage, silage or grain.

This study was carried out to evaluate 14 genotypes of six winter species for yield and nutritive value of early forage and silage or regrowth grain. The experiment was in a randomized complete block design with three replications, so that the plots consisted of seven 5.0 m-long rows spaced at 0.2 m. The seeding date was April in the three study years and fertilization followed the recommendations for the crops. During the tillering period and after cutting, urea was applied at the rate of 22.5 kg N/ha. Each plot was cut at a height of 7.0 cm from the soil to estimate the forage yield per genotype, when plants reached 30 cm height. Half the regrowth of each plot was used for silage and half for grain. Harvesting for silage was at the dough stage, from 30 to 35% DM. Nutritive value analyses were made using the near infrared spectroscopy (NIRS) technique. Rye BRS Serrano was superior for green forage, silage, and total forage yield (green forage + silage) and regrowth grain yield. However, for grain yield, BRS Serrano rye was similar to BRS 277 wheat, BRS 148 and BRS 203 triticales, UPF 18 oats, and BR 1 rye. It is possible to obtain early forage using genotypes of rye, wheat, barley, and triticale, producing equivalent forage yields to those obtained with black oats pasture. Embrapa 53 triticale and UPF 18 oats yielded more digestible green forage, but the silages had digestibility similar to barley silage.

Efeito de sistemas de produção de grãos e de pastagens sob plantio direto sobre o nível de fertilidade do solo após cinco anos

Soil fertility characteristics were evaluated on a typical dystrophic Red Latosol located in Passo Fundo, Rio Grande do Sul, Brazil, after five years of combined production systems (1993 to 1997). The effects of integrated grain production systems and with winter annual and perennial pastures under no-tillage were assessed. Four production systems were evaluated: system I (wheat/soybean, white oat/soybean, and common vetch/corn); system II (wheat/soybean, white oat/soybean, and grazed black oat + grazed common vetch/corn); system III [perennial cool season pastures (fescue + white clover + birdsfoot trefoil)]; and system IV [perennial warm season pastures (bahiagrass + black oat + rye grass + red clover + birdsfoot trefoil)]; and system V (alfalfa for forage), which was established in an adjacent area in 1994. The treatments were arranged in a randomized complete block design, with four replications under no-tillage. The production systems increased the contents of organic matter, extractable P, and exchangeable K, mainly at 0-5 cm depth. There was an increase in the pH value and exchangeable Ca + Mg contents in the first four production systems from the soil surface (0-5 cm) to deeper layers (15-20 cm). The reverse occurred with values of exchangeable Al. The systems with grazed perennial pastures showed higher organic matter content at soil surface, as compared to systems with annual pastures.

Conversão e balanço energético de sistemas de produção de grãos com pastagens sob plantio direto

Data obtained from experiments conducted, from 1990 to 1995, at the Universidade de Passo Fundo, Rio Grande do Sul State, Brazil, were evaluated with the objective to study the energy conversion and balance of four grain production systems with annual winter pastures. Four grain production systems were evaluated: system I (wheat/soybean, black oats/soybean, and black oats/soybean); system II (wheat/soybean and black oats + common vetch/corn); system III (wheat/soybean, black oats + common vetch/soybean, and black oats + common vetch/corn); and system IV (wheat/soybean, white oats/soybean, and white oats/soybean). Both winter and summer crops were grown under no-tillage. The trial was set up blocks at random, with three replications and plots with 500 m2. Systems II and III showed higher energy conversion (5.78 and 5.44) and balance rates (23,728 and 21,741 kg/Mcal), as compared to systems I (3.79 and 11,553 kg/Mcal) and IV (4.33 and 12,879 kg/Mcal), respectively. It was evident that the integration crop-livestock under no-tillage is a viable system, since the energetic conversion and balance showed positive results; actually, these rates were significantly higher in the systems including corn crop.

Fisiologia foliar e qualidade enológica da uva em videiras infectadas por vírus

Leaf physiology and enologic grape quality of virus-infected plants Viruses may induce metabolic and structural disarray in plant cells to varying degrees depending on viral species and plant susceptibility. With this focus, grapevine plants (Vitis vinifera) cvs. Cabernet Franc and Cabernet Sauvignon, symptomless and showing symptoms of virus-infection, in two commercial vineyards were comparatively analyzed. The parameters were: 1. photosynthetic potential (light-saturated rate of photosynthesis, saturating light intensities, light compensation point, dark respiration rate, apparent quantum yield, chlorophyll a and b); 2. foliar carbon metabolism (total soluble sugars and starch), and 3. enologic quality of the produced grapes (total soluble solids - °Brix, density, pH and titerable total acidity in the must; total color intensity and total polyphenols in berry skins) were recorded. In symptomatic plants Grapevine leafroll-associated virus 2 (GLRaV-2) and Rupestris stem pitting-associated virus (RSPaV) have been detected by ELISA carried out for six viruses. The virus infections induced significant reductions in chlorophyll content and in photosynthetic potential of both cultivars. Leaves of infected plants also showed significant accumulation of carbohydrates, suggesting a blockage of carbon transport out of these tissues. Concerning the enologic quality and based on technological parameters of the must (°Brix, density, titerable total acidity and polyphenols), grapes of infected plants showed at harvest a significantly lower level of maturation. These viruses directly affect the productive capacity as well as the quality of the grapes produced by these cultivars.