DEMANDA ENERGÉTICA DA SEMEADURA DO MILHO EM DIFERENTES MANEJOS DO SOLO E ESPAÇAMENTOS ENTRE LINHAS

As diferentes condições da superfície do solo inerente a cada sistema de manejo podem afetar a demanda energética da operação de semeadura devido à complexidade de suas interações com o conjunto trator/semeadora. Assim sendo, o objetivo deste trabalho foi avaliar o efeito de dois sistemas de manejo do solo e dois espaçamentos entre linhas na demanda energética da operação de semeadura da cultura do milho. O experimento foi conduzido na Faculdade de Ciências Agronômicas (FCA) da Universidade Estadual Paulista (UNESP), campus de Botucatu-SP, em Nitossolo Vermelho Distroférrico. O delineamento experimental utilizado foi de blocos ao acaso com parcelas subdivididas e quatro repetições. As parcelas foram constituídas pelos sistemas de manejo do solo (plantio direto e preparo reduzido - escarificação) e as subparcelas pelos espaçamentos entre linhas (0,90 m e 0,45 m). Os resultados obtidos foram submetidos ao teste de Tukey a 5% de probabilidade para comparar as médias. As análises estatísticas demonstraram que a semeadura do milho no sistema plantio direto requer menor força na barra de tração, menor demanda de potência média, menor consumo específico de energia por área, menor consumo de combustível por hora e por área. A semeadura do milho no espaçamento de 0,45 m entre linhas exige maior força de tração na barra, maior demanda de potência, maior consumo específico de energia por área e maior consumo horário de combustível

Viabilidade da nabiça (Raphanus raphanistrum L.) como planta de cobertura para a cultura do milho em diferentes sistemas de manejo do solo

O presente trabalho teve como objetivo comparar dois tipos de cobertura vegetal de inverno, através de três sistemas de manejo do solo, avaliando seus efeitos no crescimento e desenvolvimento da cultura de milho. Os experimentos foram instalados e conduzidos na Fazenda Experimental Lageado, da Faculdade de Ciências Agronômicas da UNESP, Campus de Botucatu, no período compreendido entre fevereiro de 2005 e maio de 2006, em NITOSSOLO VERMELHO Distroférrico, cultivado há nove anos com os mesmos sistemas de manejo do solo. Os experimentos foram constituídos de seis tratamentos com quatro repetições utilizando o delineamento experimental de blocos ao acaso com parcelas subdivididas. As parcelas foram constituídas por três sistemas de manejo do solo (preparo convencional, constituído por uma gradagem pesada e duas gradagens leves; cultivo mínimo, escarificador equipado com disco de corte e rolo destorroador, trabalhando na profundidade entre 25 e 30 cm e plantio direto, com dessecação da vegetação de cobertura por meio de aplicação de herbicida) e as subparcelas foram compostas por duas culturas de inverno (nabo forrageiro, Raphanus sativus L. e nabiça, Raphanus raphanistrum L.), que conseqüentemente formaram os dois tipos de coberturas vegetais, sobre as quais foram realizados os sistemas de manejo do solo para a implantação da cultura de milho. Os dados obtidos foram submetidos à análise de variância com teste de Tukey a 5% de probabilidade para comparar as médias. As análises estatísticas demonstraram que o sistema de plantio direto apresentou maior densidade e resistência mecânica do solo à penetração, quando comparado ao preparo convencional e ao cultivo mínimo. O cultivo mínimo apresentou maiores valores de profundidade de trabalho, área de solo mobilizada e capacidade de campo efetiva e menores valores de tempo efetivo demandado, uso específico...This paper aims to compare two types of winter vegetal covering, through three soil tillage systems, evaluating their effects in growth and development of corn crop. Experiments were installed and carried out at Lageado Experimental Farm at Agricultural Science University of UNESP, Botucatu Campus, from february 2005 to may 2006, in Distroferic Red Nitosoil, which has been cultivated for nine years under the same soil tillage systems. Experiments were carried out in six treatments with four repetitions, using randomized experimental blocks with subdivided parts. Parts were made up by three soil tillage systems (conventional tillage, made up by one heavy harrow and two leveling harrow; minimum tillage, with chisel plow with cut disk and roll, working at 25 to 30 cm deep and notillage, with herbicide drying coverage vegetation) and subparts were made up by two winter crops (Raphanus sativus L. and Raphanus raphanistrum L.) which made up the two vegetal coverings over which the soil tillage systems were carried out for corn cropping. Obtained data were analyzed by Turkey variance test at 5% of probability for comparing averages. Statistical analysis showed that no-tillage system had higher density as well as mechanical soil resistance to penetration, when compared to conventional and minimum tillages. Minimum tillage system showed higher values of work deepness, mobilized soil area as well as effective field capacity and lower values of demanded real time, specific energy use and fuel consumption. For Raphanus sativus L. and Raphanus raphanistrum L., sowing it was observed that no-tillage system showed lower traction force, steering bar power, demanded real time, specific energy use and fuel consumption. Raphanus raphanistrum L. showed higher length, volume and root dry matter compared to Raphanus sativus L., meantime not observed statistical differences between both. Raphanus raphanistrum...(Complete abstract click electronic access below

Root volume and dry matter of peanut plants as a function of soil bulk density and soil water stress

Soil compaction may be defined as the pressing of soil to make it denser. Soil compaction makes the soil denser, decreases permeability of gas and water exchange as well as alterations in thermal relations, and increases mechanical strength of the soil. Compacted soil can restrict normal root development. Simulations of the root restricting layers in a greenhouse are necessary to develop a mechanism to alleviate soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. This experiment aimed to assess peanut (Arachis hypogea) root volume and root dry matter as a function of bulk density and water stress. Three levels of soil density (1.2, 1.4, and 1.6g cm-3), and two levels of the soil water content (70 and 90% of field capacity) were used. Treatments were arranged as completely randomized design, with four replications in a 3×2 factorial scheme. The result showed that peanut yield generally responded favorably to subsurface compaction in the presence of high mechanical impedance. This clearly indicates the ability of this root to penetrate the hardpan with less stress. Root volume was not affected by increase in soil bulk density and this mechanical impedance increased root volume when roots penetrated the barrier with less energy. Root growth below the compacted layer (hardpan), was impaired by the imposed barrier. This stress made it impossible for roots to grow well even in the presence of optimum soil water content. Generally soil water content of 70% field capacity (P<0.0001) enhanced greater root proliferation. Nonetheless, soil water content of 90% field capacity in some occasions proved better for root growth. Some of the discrepancies observed were that mechanical impedance is not a good indicator for measuring root growth restriction in greenhouse. Future research can be done using more levels of water to determine the lowest soil water level, which can inhibit plant growth

Cotton root volume and root dry matter as function of high soil bulk density and soil water stress

Soil compaction reduces root growth, affecting the yield, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in greenhouses are necessary to develop mechanisms which alleviate soil compaction problems. The selection of three distinct bulk densities based on the Standard Proctor Test is also an important factor to determine which bulk density restricts root penetration. This experiment was conducted to evaluate cotton (Gossypium hirsutum L.) root volume and root dry matter as a function of soil bulk density and water stress. Three levels of soil density (1.2, 1.4, and 1.6 g cm-3), and two levels of water content (70 and 90% of field capacity) were used. A completely randomized design with four replicates in a 3×2 factorial pattern was used. The results showed that mechanical impedance affected root volume positively with soil bulk density of 1.2 and 1.6 g cm-3, enhancing root growth (P>0.0064). Soil water content reduced root growth as root and shoot growth was higher at 70% field capacity than that at 90% field capacity. Shoot growth was not affected by the increase in soil bulk density and this result suggests that soil bulk density is not a good indicator for measuring mechanical impedance in some soils

Corn root length density and root diameter as affected by soil compaction and soil water content

Negative effects of soil compaction have been recognized as one of the problems restricting the root system and consequently impairing yields, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in green house studies are necessary for the development of mechanism which alleviates soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. The experiment was conducted to assess the root length density and root diameter of the corn (Zea mays L.) crop as a function of bulk density and water stress, characterized by the soil density (1.2; 1.4, and 1.6 g cm -3), and two levels of the water content, approximately (70 and 90% field capacity). The statistical design adopted was completely randomized design, with four replicates in a factorial pattern of (3 × 2). The PVC tubes were superimposed with an internal diameter of 20 cm with a height of 40 cm (the upper tube 20 cm, compacted and inferior tube 10 cm), the hardpan with different levels of soil compaction were located between 20 and 30 cm of the depth of the pot. Results showed that: the main effects of subsoil mechanical impedance were observed on the top layer indicating that the plants had to penetrate beyond the favorable soil conditions before root growth was affected from 3.16; 2.41 to 1.37 cm cm -3 (P<0.005). There was a significant difference at the hardpan layer for the two levels of water and 90% field capacity reduced the root growth from 0.91 to 0.60 cm cm -3 (P<0.005). The root length density and root diameter were affected by increasing soil bulk density from 1.2 to 1.6 g cm -3 which caused penetration resistance to increase to 1.4 MPa. Soil water content of 70% field capacity furnished better root growth in all the layers studied. The increase in root length density resulted in increased root volume. It can also be concluded that the effect of soil compaction impaired the root diameter mostly at the hardpan layer. Soil temperature had detrimental effect on the root growth mostly with higher bulk densities

Antecipação da adubação de semeadura do milho em dois sistemas de manejo do solo

Cada sistema de manejo do solo é trabalhado de maneira própria, alterando de forma diferenciada suas propriedades químicas, físicas e biológicas, podendo requerer modificações nas recomendações e no manejo da adubação. Com a finalidade de avaliar o desempenho de três cultivares de milho em relação à adubação realizada em pré-semeadura, comparada à adubação na semeadura, em dois sistemas de manejo do solo, foi realizado este estudo. O experimento foi conduzido na Faculdade de Ciências Agronômicas da UNESP, campus de Botucatu-SP, no período de novembro de 2003 a maio de 2004, em Nitossolo Vermelho distroférrico. O delineamento experimental utilizado foi o de blocos ao acaso com parcelas subsubdivididas e quatro repetições. As parcelas foram constituídas pelos sistemas de manejo do solo (plantio direto e preparo reduzido com escarificação); as subparcelas, pelas épocas de adubação (adubação de pré-semeadura na superfície do solo, realizada 22 dias antes da semeadura do milho, e adubação feita junto com a semeadura do milho, sendo os fertilizantes incorporados ao solo); e as subsubparcelas, pelos cultivares de milho (DKB 333B, CO 32 e AL Bandeirante), totalizando 12 tratamentos. Os dados de produtividade, componentes de produção e teores de N, P e K no tecido foliar foram submetidos à análise de variância e às análises multivariadas de agrupamentos e de componentes principais. Os sistemas de manejo do solo não influíram no desempenho da cultura do milho, tampouco as épocas de adubação. As diferenças observadas nos componentes de produção e no desempenho da cultura do milho foram decorrentes, principalmente, da divergência genética dos cultivares de milho.Each soil tillage system has its proper characteristics, which have distinct effects on the chemical, physical and biological soil properties, and may require adaptations of fertilization recommendations and management. This study was conducted to evaluate the performance of three maize cultivars with fertilizer application before and at sowing in two soil tillage systems. The experiment was carried out at the Faculdade de Ciências Agronômicas, UNESP, Botucatu-SP campus, from November 2003 to May 2004, in a Dystric Nitosol (FAO). The experimental design was in randomized blocks with split-split plots and four repetitions. The main plots consisted of two soil tillage systems (no-tillage and reduced tillage with chisel plow), the split-plots of fertilizer application time (surface fertilizer application 22 days before maize sowing and fertilizer application incorporated to soil simultaneously to maize sowing) and split-split-plots of maize cultivars (DKB 333B, CO 32 and AL Bandeirante), totalizing 12 treatments. The data of productivity, yield components and N, P and K contents in the leaf tissue were submitted to analysis of variance and multivariate analysis of Grouping and Principal Components. The soil tillage systems did not influence the performance of the maize crop, neither the timing of starter fertilizer application. The differences observed in the yield components and the maize crop performance were mainly due to genetic divergences among the maize cultivars