Simulated and experimental analyses of a toothed rolling coulter for cutting crop residues

Rolling cutting coulters are extensively used to cut plant residues, left on the soil surface, so as to facilitate the work of tillage tools in reduced tillage or direct drilling practices. Four basic patterns of these coulters are available in the market: smooth, notched, ripple, and wave. These coulters have operational problems and usually do not cut the residue efficiently. When the soil is dry, they demand high vertical load to penetrate and, when the soil is wet, they push the residue into the soil without cutting it. This work presents a new geometry for cutting coulters, making them capable of cutting through residue under any soil condition, eliminating build-up and reducing implement draught. The work was developed in two stages: a computational routine to calculate the dimensions of the coulter and to simulate its behaviour; and laboratory tests carried out with three-teeth coulters with different diameters. The results showed that the toothed coulter performed adequately in cutting the residues. The vertical load necessary for soil penetration at 70 mm working depth demanded by the toothed disc coulter varied between 1.5 to 2.1 kN. The moment demanded by the toothed coulter varied from 55.2 up to 86.5 Nm. (c) 2006 IAgrE. All rights reserved Published by Elsevier Ltd.96219320

Protective gloves on manual sugar cane cutting are really effective?

Problems related to the use of personal protective equipment (PPE), specially the use of protective gloves for the manual sugar cane cutting, motivated this research, made possible by a tripartite negotiation involving the Ministry of Labor, the Union of Rural Workers and the Employer's Association of sugarcane agribusiness. The main objective was to evaluate, from an ergonomics perspective, the impact of use of the gloves during the manual cane sugar cutting, raising questions on safety, effectiveness and comfort. The research was carried in a sugarcane industry of Sao Paulo for two seasons involving 47 workers who made a qualitative analysis of acceptance of four models of protective gloves. The methodology included the use of semi-structured interviews, questionnaires and field observations and the experimental determination of the coefficient of static friction developed between the gloves and the surfaces of the machete handle. The main results indicate the general inadequacy of the gloves currently used forcing the employees to improvise. Workers found the glove of leather and nylon scraping the best reported for comfort in use. The overall results highlight the problem of detachment of test standards for the manufacture of PPE, ignoring users and the activity to be performed.4114963496

Assessment of sugarcane trash for agronomic and energy purposes in Brazil

Due to new possibilities for using sugarcane (Saccharum spp.) trash for electricity generation, and the production of 2nd generation ethanol and others chemicals, the interest for its recovery has increased. However, the question of how much trash can be removed from sugarcane field still needs to be clarified. This study evaluated the amount of dry matter, nutrients content, structural compounds and efficiency of the enzymatic hydrolysis of the hydrothermal pretreated materials for tops and dry leaves in samples from sugarcane varieties. Tops and dry leaves present differences in nutrients content and moisture. Therefore, the amount of trash to be collected should not be simply based on percentages, but also should take into account the different fractions of the crop residues. For instance, around 80 % of N, P and K were derived from tops. Therein, the environmental indicators of the entire chain of sugarcane could be benefited because more nutrients would be recycled and less mineral fertilizers might be used for sugarcane production if tops are left on the field. Further, the tops have seven times more moisture than dry leaves and higher amounts of extractives (organic compounds of low molecular weight). Moreover, as the result of yield obtained in the pretreatment steps for dry leaves were superior to the tops and the glucose yields obtained in the enzymatic hydrolysis step were similar, it can be predicted that for second generation ethanol production, it is more viable to recover parts of the dry leaves fraction, leaving the tops on the field.70530531