Leandro M. Gimenez

Profundidade de deposição de semente de milho na região dos Campos Gerais, Paraná

No Tillage system is fully incorporated to farming in the region of Campos Gerais, state of Parana. Accuracy and precision in the planting process are items of great importance for the success of this system. In order to evaluate the planting process, thirty eight farms were selected as sites for analysis of the placement depth of seeds. The research area was 4 or 5 planting rows, evaluating 10 plantlets per row. The average seed depth was around 46 mm, and significant differences between rows were observed in 21 areas. The average coefficient of variation was around 20%, the statistical limit between medium and high. Analyses of other parameters show that those coefficients may represent different errors in the process. The planting process in Campos Gerais can be considered efficient regarding to the average seed depth. However, the analysis of variability implies de need of actions concerning to anthropic and machinery factors.

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.

Utilização de dados georreferenciados na determinação de parâmetros de desempenho em colheita mecanizada

The information about field efficiency and capacity of agricultural machinery is very important for the management of agricultural mechanized systems, helping supporting administration at making decisions. The information is usually obtained by manual ways using resources like, time and people. By considering the importance of the information and the cost of the acquisition, the proposal of this work was to present a methodology to determination field capacity, using information from a yield monitor. Therefore a time motion study, from data files gathered by yield monitors, during a harvester operation in eight farms in the state of Parana (Brazil) was carried out. The time difference related to the harvester in the field was calculated from the collected data and a map of the differences was developed. Using the differences it was possible to get the field efficiency, field capacity and throughput capacity maps. The suggested methodology is practicable and allows the evaluation, based on a sample that embraces many points and is automatically obtained, of the harvester with no additional expense for the farmers.

Diagnóstico da mecanização em uma região produtora de grãos

As maquinas agricolas, depois da terra, representam o maior investimento para o agricultor, e sua adequacao ao tamanho da propriedade e um fator fundamental na reducao dos custos. Ha, entretanto, no Pais, carencia de informacoes que permitam a analise e a comparacao sobre a eficiencia do uso desses equipamentos. Com isso, o objetivo deste trabalho foi avaliar o estado da arte e realizar diagnostico quanto a posse e uso de sistemas mecanizados em propriedades agricolas. Para tanto, elaborou-se um questionario que foi aplicado a 139 propriedades de diferentes tamanhos na regiao dos Campos Gerais, Estado do Parana, e na regiao sul do Estado de Sao Paulo. Essas propriedades foram divididas em estratos de 100-300 ha, 300-600 ha, 600-900 ha e acima de 900 ha. Os resultados mostram que os operadores nao recebem suficiente treinamento, as propriedades maiores utilizam-se mais eficientemente das maquinas, a potencia por area dos tratores nas menores areas e o dobro das maiores e poucos fabricantes dominam o mercado na regiao.

Energy embodiment in Brazilian agriculture: an overview of 23 crops.

The amount of energy required to produce a commodity or to supply a service varies from one production system to another and consequently giving rise to differing levels of environmental efficiency. Moreover, since energy prices have been continuously increasing over time, this energy amount may be a factor that has economic worth. Biomass production has a variety of end-products such as food, energy, and fiber; thus, taking into account the similarity in end-product of different crops (e.g.: sunflower, peanuts, or soybean for oil) it is possible to evaluate which crops require less energy per functional unit, such as starch, oil, and protein. This information can be used in decision-making about policies for food safety or bioenergy. In this study, 23 crops were evaluated allowing for a comparison in terms of energy embodied per functional unit. Crops were grouped as follows: starch, oil, horticultural, perennial and fiber, to provide for a deeper analysis of alternatives for the groups, and subsidize further studies comparing conventional and alternative production systems such as organic or genetically modified organisms, in terms of energy. The best energy balance observed was whole sugarcane (juice, bagasse and straw) with a surplus of 268 GJ ha−1 yr−1; palm shows the highest energy return on investment with a ratio of approximately 30:1. For carbohydrates and protein production, cassava and soybean, respectively, emerged as the crops offering the greatest energy savings in the production of these functional foods.

Carbon stocks of a Rhodic Ferralsol under no-tillage in Southern Brazil: spatial variability at a farm scale

The objective of this study was to determine, at a farm level, the spatial variability of organic carbon stock (CS) at different depths on a field of 1 soil type in long-term (13-year) crop production under no-tillage. The crop rotation comprised soybean [Glycine max (L.) Merr.] alternating with maize (Zea mays L.) in the summer season. For the winter season, wheat (Triticum aestivum L.) was cropped in rotation with black oat (Avena sativa L.), a cover crop. The 12.5-ha field was sampled at a density of 6.25 samples/ha. Within the coarse grid, 2 dense grids with 20-, 10-, and 5-m spacing were established. Soil samples were collected at all grid nodes and analysed for soil organic carbon and bulk density. The CS at 0–0.05, 0.05–0.10, and 0.10–0.20 m was corrected for equal soil mass. Geostatistics was used for the estimation of spatial distribution of CS at 3 soil depths. We found that CS variation was low to medium (CV 6.7–19.4%). The variograms of CS at all depths were best fitted by spherical models and showed ranges of 120 m, except at 0–0.05 m (range 109 m). At 0–0.20 m depth, CS was 15.2–24.5 t/ha (CV 8.2%, range 120 m). The use of geostatistics reveals a powerful tool for the spatial estimation of CS at depth of a Rhodic Ferralsol under no-tillage, and demonstrated CS variation on a 12.5-ha area, even though soil and crop management were the same for >10 years.