Volnei Pauletti

Comportamento do NDVI obtido por sensor ótico ativo em cereais

The objective of this work was to evaluate the behavior of the normalized difference vegetation index (NDVI), with an active optical sensor, in wheat, triticale, barley and corn crops. Experiments were conducted in Parana and Sao Paulo, comparing different soil classes, N rates and sources, and wheat varieties. The following variables were determined: NDVI, N foliar content, dry mass and crop yield. Regression analyses were performed between NDVI and applied N rates, N foliar content, dry mass and yield. Correlation analyses among the variables were performed. Wheat, triticale and barley crops showed response to increasing N rates by the increase in the NDVI readings, to N foliar content and to yield. Measured by the used active optical sensor the NDVI shows high potential for N management wheat, triticale and barley crops, and low potential for corn crops. There is interference of wheat varieties in the active optical sensors readings.

Nitrogen immobilization of urea and ammonium sulphate applied to maize before planting and as top-dressing in a no-till system

Ammonium sulfate (AS) and urea (U), labeled with 15N, were applied to no-till maize, 33 days before and 10 days after sowing, at a single rate of 80 kg ha-1 of N incorporated 5-7 cm deep along furrows spaced 0.8 m. Corn was sown after black oat (Avena strigosa Schieb.).The amount of immobilized N and of N-fertilizer recovered by corn plants was evaluated at the following plants stages: 4-5 leaves, 11-12 leaves, flowering, and at harvest. Treatments were applied in a randomized block design with three replications. The analysis of variance was performed based on one factorial scheme (2 x 6) with two sources in pre-planting (AS and U) on six sampling dates, and on a second (2 x 3) with two sources in top-dressing on three sampling dates. This field experiment was carried out on a Typic Acrustox in Uberlandia, Minas Gerais state, Brazil. Pre-planting applications resulted in a maximal AS-N immobilization 22 days after fertilizer application (9.1 kg ha-1 or 11.4 % of applied N), whereas the maximum immobilization of U-N occurred 11 days after fertilizer application (46.5 kg ha-1 or 58.1 % of applied N). Until harvest, the plants (aerial part, grains and roots) had accumulated 66.0 and 47.9 of AS-N and U-N, respectively (use efficiency of 82.5 and 59.9 % of applied N). N top-dressing resulted in 12.5 % less N immobilized applied as both sources in all growth stages, evidencing that the soil biomass did not compete with the plants for N-fertilizer, in agreement with results of the growing season 1999/2000. In both growing seasons (1999/2000 and 2000/2001) corn plants assimilated an average 8.9 and 15.4 kg ha-1 of AS-N for each kg of immobilized N-fertilizer from pre-planting and top-dressing, respectively, in the stage of 11-12 leaves and at flowering. For U-N these values were 4.5 and 5.2 kg ha-1, respectively, presenting a lower ratio of immobilized AS-N in top-dressing. Highest corn yields were obtained in the AS treatments (mean grain yield of 8.543 kg ha-1) independent of the application time. Urea treated plants obtained average grain yields of 7.767 kg ha-1 for both application periods. These results show that for pre-planting fertilizers the immobilization-mineralization N turnover was faster in the AS than in the U-N treatment. Consequently, N assimilation by corn plants was higher in the AS treatments. Only U-N was significantly immobilized more also in the second growing season when top-dressed, thus limiting plant N uptake.

Efeitos em longo prazo da aplicação de gesso e calcário no sistema de plantio direto

Os efeitos da calagem e da gessagem sao amplamente conhecidos na literatura, mas a sua magnitude em relacao aos efeitos no perfil do solo e dependente do tempo apos a aplicacao desses insumos. Dessa maneira, o objetivo deste trabalho foi avaliar em longo prazo a aplicacao conjunta de gesso e calcario nos atributos quimicos de um solo em rotacao de culturas, no sistema de plantio direto. O experimento foi conduzido em uma propriedade rural no municipio de Jaguariaiva, PR, em um Latossolo Vermelho-Amarelo distrofico tipico, de textura areia franca, durante os anos de 2002 a 2008. O experimento foi conduzido em blocos ao acaso sob esquema fatorial com 10 tratamentos, sendo cinco doses de gesso agricola (0; 1,5; 3,0; 6,0; e 12,0 Mg ha-1) e duas doses de calcario (0 e 3,42 Mg ha-1), com tres repeticoes. Foram avaliadas no decorrer dos 72 meses as especies aveia-preta-comum (2004, 2006 e 2007), milho (2005/2006), trigo (2003) e soja (2003/2004, 2004/2005, 2006/2007 e 2007/2008). Realizaram-se amostragem e analise de solo nos anos de 2005 e 2008 ate 100 cm de profundidade e de tecido foliar da soja, na safra de 2007/2008. A aplicacao de calcario corrigiu o pH, aumentou a concentracao de Ca e Mg e diminuiu o Al, nas camadas superficiais do solo. O gesso proporcionou incremento no pH e nas concentracoes de Ca e S em profundidade, lixiviou Mg e nao lixiviou o K. A calagem elevou a produtividade do milho, da soja (uma das quatro safras avaliadas) e da aveia- preta. O gesso favoreceu a produtividade do milho e do trigo e a da soja, somente quando houve deficiencia hidrica. Quando, no entanto, nao houve deficiencia hidrica, altas doses de gesso prejudicaram a produtividade de graos de soja por inducao de deficiencia de Mg.

Formas químicas, disponibilidade de manganês e produtividade de soja em solos sob semeadura direta

This field study had the following objectives: to determine the most appropriate micronutrient extractor to evaluate manganese bioavailability in soils under no-tillage; to evaluate the interaction of soil manganese with humic acids in soils under no-tillage with and without manganese deficiency through electronic paramagnetic resonance (EPR); and to evaluate manganese fractions (exchangeable, organic, oxides and residual) after manganese addition in soils under no-tillage with and without previous manganese deficiency for soybean. Four sites (I to IV) were selected to study the response curve to manganese (0 to 48 kg ha-1) fertilization in soybean. Sites I to III were located in Tibagi, state of Parana (PR), Brazil and site IV was in Castro (PR). Manganese rates affected the manganese concentrations in the soil, but not the manganese concentrations in leaves and the amount of manganese taken up by plants. Exchangeable, organic and oxide forms of manganese increased with the increasing rates applied at site I, with the largest increase being observed for the organic fraction (changed from 5.4 mg kg-1 manganese in the control to 35.1 mg kg-1 of manganese in the highest manganese dose). Manganese was not detected by EPR in the solid samples of humic acid - pH 3.0. Manganese quantification in the same samples after nitric-perchloric digestion, along clear signals of manganese detected by EPR in samples of humic acid - pH 2.4, indicated that manganese in the samples was strongly linked to the functional (probably carboxylic) groups of humic acid. The fact that there was no effect of manganese on soybean yield might be due to the complexation of the nutrient by soil organic matter. In general, DTPA-TEA was the most reliable manganese extractor to evaluate manganese availability to soybean under no-tillage.

Esterco líquido de bovinos leiteiros combinado com adubação mineral sobre atributos químicos de um Latossolo Bruno

This study aimed to evaluate the influence of fertilization doses of liquid dairy manure combined with mineral fertilizer on the chemical properties of a Brown Oxisol, in no-tillage system and winter and summer crop rotation (sorghum/black-oat/corn/ryegrass/corn/ryegrass), for silage production, in the layers 0-5, 5-10, 10-30, 30-50 and 50-80 cm. The treatments were distributed in three randomized blocks, divided in 12 plots per block, in a 3 x 4 factorial arrangement, with three mineral fertilizer levels (0, 50 and 100 % of the dose recommended for the crops) and four organic fertilizer levels (0, 30, 60 and 90 m3 ha-1 year-1). The liquid dairy manure increased the pH linearly in the 0-5 cm layer and quadratic in the 30-50 cm layer. The mineral fertilization reduced the pH values linearly in the 0-5 and 5-10 cm layers, with quadratic effect at 50-80 cm. The potential acidity decreased in 5-10 cm, with quadratic pattern at 10-30 cm. The exchangeable Ca2+ increased in the 0-5 cm layer with manure, but no effect of mineral fertilization on this attribute was verified. An increase in exchangeable Mg2+ levels was observed in the manure treatments to a depth of 30 cm; under mineral fertilizer, increases were observed from 30 cm downwards. There was a linear increase of base saturation through manure doses, down to a depth of 10 cm, and the mineral fertilization decreased base saturation at 5-10 cm, with a quadratic effect at 50-80 cm.

Época de aplicação de nitrogênio no milho cultivado em sucessão à aveia preta no sistema plantio direto

This paper has as main goal the evaluation of lhe effect of nitrogen application on the yield of no tillage com crop, planted over black oats. Experiments were conducted m the agricultural year of 1996/97 in three experimental units of the ABC Foundation located in the Campos Gerais Region of the state of Parana. The experimental design was a split-plot randomized block, being the plot treatments the two doses of N applied to the oats crop (O and 30kg ha-1 in the planting time) as the main plots and as the time of application of N in the com crop (no nitrogen; 30kg ha-1 in the planting plus 90kg ha-1 broadcasting in the 6a leaf time; 90kg ha-1 during the oats crop management plus 30kg ha-1 in the com planting; and 120kg ha-1 during the oats crop management plus 30kg ha-1 in the com planting) as split plot treatments. It was verified the oats crop fertilization dia not influenced com yield. The com yield was not affected by anticipated N application usually used in corns broadcasting.

Rendimento de grãos de milho e soja em uma sucessão cultural de oito anos sob diferentes sistemas de manejo de solo e de culturas

To establish a rational and sustainable use of the soil it is necessary to know the effect of different tillage systems on production considering that this factor is directly related to its choice. The present experiment had the objective to evaluate the grain yield under different soil tillage systems after eight years. The experiment was carried out in an oxisoil, in Ponta Grossa - PR, Brazil. The treatments were: no tillage, conventional tillage (one plow and two light disking), minimum tillage (two light diskings), and no tillage with chisel tillage every three years. The experiment was arranged in randomized blocks with three replications. The tillage systems did not affect the grain yield of corn. In 1998, the grain yield of soybean showed that conventional tillage and minimum tillage were significantly higher than no tillage. However, in 2000, the soybean cultivar was replaced by BRS 133, and grain yield was significantly lower in conventional tillage and minimum tillage than no tillage.

Preparo do solo em áreas de produção de grãos, silagem e pastejo: efeito na resistência tênsil e friabilidade de agregados

The understanding and quantification of soil use and management on the soil physical quality are important to develop and select sustainable agricultural systems. The purpose of this study was to evaluate the structural quality of a clayey Brazilian Oxisol under different production and soil tillage systems by measuring the tensile strength (TS) and to quantify aggregate friability (F). The study was conducted in Castro, Parana state, in southern Brazil, using three production systems and seven soil tillage types, in a randomized block design. The following production systems were evaluated: (PS I) - ryegrass for soil cover (winter) and corn for grain production (summer); (PS II) ryegrass for haylage/silage and corn for grain production; and (PS III) - ryegrass for grazing and corn for grain production. Seven types of soil tillage were evaluated in each system: (G1) - plow harrow in winter, depth 0.15 m; (G2) - plow harrow in winter and summer, depth 0.15 m; (Plow) - disk plow, depth 0.20 m; (Laser wing subsoiler) - subsoiler wing tips, to a depth of 0.45 m; (Subsoiler) - subsoiler, depth 0.80 m; (Aerator) - soil aerater Aeromix®; and (NT) - No-tillage, where ryegrass was sown using a double disc and corn with a coulter. From each experimental plot soil blocks (0.20 x 0.15 x 0.07 m) were taken which were broken up by hand in their natural aggregates. Then, the aggregates were air-dried for 24 h and passed through sieves with diameters of 12.5 and 19 mm. Forty aggregates from each block were selected and tested for indirect tension to determine TS and quantify F. TS was influenced by the production systems and soil tillage types. The lowest and the highest TS values were found in the soil under grazing and the NT system, respectively. Friability was less sensitive to differentiate production systems and soil tillage types.

Mensuração da condutividade elétrica do solo por indução e sua correlação com fatores de produção

Soil electrical conductivity obtained by contact or induction sensors has been used as a variable that correlates with soil characteristics of interest on spatial variability analysis. This work reports the experience done in a 19 ha no-till field aiming to correlate soil electrical conductivity (EC) measured by an induction sensor and soil chemical fertility properties, soil texture, altitude, humidity, soil fertility and corn and soybean yield between 2000 and 2002. Yield data was obtained using a yield monitor; EC and the other parameters were sampled based on a regular grid. Data were submitted to a spatial analysis generating maps for correlation analysis among the factors. EC sensor was limited on its operation, especially for not having a data logger, and requiring frequent calibrations. EC data were strongly spatially dependent but with inverse correlation between the two reading depths. Clay and water content resulted in positive correlations with EC in the shallow reading but at levels lower than expected.

Yield response to fertilization strategies in no-tillage soybean, corn and common bean crops

Two research fields were conducted on a Haplohumox from 1998 and to 2005. The study aimed to evaluate the strategies for starter fertilizer application on corn, soybean and common bean yield as well as the accumulation of earlier dry matter for corn in a no-tillage crop rotation system in south of Brazil. There was no increase in the yield of soybean with phosphorus and potassium application for at least seven seasons, while corn and common bean showed increased yields with phosphorus, potassium and nitrogen application. For soybean, corn and common beans in no-tillage systems with high levels of phosphorus and medium of potassium, the starter fertilizer can be applied in any of the methods evaluated and in any of the period considered. The presence or absence of potassium in the furrow, phosphorus sources and row preparation components provided similar yields to corn, soybean and common bean.