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The practical implementation of precision crop production nowadays is becoming more and more widespread. Numerous experiments and farmers’ practical experiences verify the positive impacts of precision nutrient supply on farming. Precision weed control started to spread later, partly due to technical difficulties, partly to the lack of necessary software support that was developed later. The introduction of a new technology requires complex farm-management decisions, including the consideration of economic correlations (costs-yield-income) as well as high-level skills and significant investments from the farmer. These investments can be returned from the income surplus realized through increasing yields and decreasing farming costs. Extra income can also come from the decreasing material costs which, however, do not necessarily compensate the extra costs of implementing the new technology and depends very much on the utilization of savings from different herbicide doses used for the treatment of plots, considering the soil qualities. This study, utilising the data of a technological experiment carried out in Hungary, presents the results of a stochastic simulation model developed with the adaptation of finite element method. The examination was executed at sub-plot level, dividing the plots into small parcels. Our aim was to examine the impact of precision nutrient application and differentiated spraying of herbicides on production costs and yield, as well as the impact of changes on gross margin (income) and the returns on technological development.

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Cereal Research Communications
Authors: E. Firatligil-Durmuş, A. Sýkorová, E. Šárka, Z. Bubník, M. Schejbal and J. Příhoda

Digital image analysis was used to test the quality parameters of six varieties of Triticum aestivum L. and one variety of Triticum duro-compactum L. — projected area, equivalent diameter, MaxFeret and MinFeret (minimum or maximum perpendicular distance between parallel tangents touching opposite sides of the profile of the chosen object), perimeter, thickness and crease depth (both measured using a digital calliper) of a kernel ranging from 16.52–20.22 mm 2 , 4.58–5.07 mm, 16.70–20.82 mm, 6.21–7.29 mm, 3.32–3.78 mm, 2.69–3.12 mm, 0.23–0.42 mm. The size data were used for calculation of volumes and surface areas of wheat kernels modelled as a general ellipsoid. The calculation of surface area using finite element method (FEM) was based on computer software MAPLE 9.0 and the results were compared with a simplified method. The volumes of kernels from the ellipsoid model were corrected with consideration of measured average crease depth; the difference was then max. 3.6%.We tested the correlation of volume and surface areas obtained from the ellipsoidal model with the measured projected areas; the resulting high correlation coefficient for the varieties of Triticum aestivum enables the use of only 2D image analysis measurement, for quick estimation of surface and volume parameters, without time consuming thickness measuring. However, the shape of Triticum duro-compactum kernels was a little different and the designed geometrical model was thus not suitable.We recommend image analysis as a simple and rapid method for obtaining the parameters of wheat grain for engineering purposes.

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Cereal Research Communications
Authors: A. Nyéki, G. Milics, A.J. Kovács and M. Neményi

.M. , Neményi , M. 1999 b. Tillage tool design by the finite element methods: Part 1 . Finite element modelling of soil plastic behaviour. J. Agric. Eng. Res. 72 : 37 – 51

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