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Investigations were carried out on five different soils at different moisture conditions. Soil resistance was measured with a hydraulic dynamograph on a single bottom plough operated with a tractor at 20-22 cm depth with a width of 60 cm. On light soils (sandy and loess soils) the soil resistance to ploughing was relatively small. The amplitude of instantaneous soil resistance measured from the mean value was also small. In the heavy loam soils, these variations were high. The highest instantaneous as well as the total soil resistance were found on the soil made of limy rock soil with a low organic matter. The magnitude of instantaneous soil resistance increased considerably with soil drying. The tillage tools must, therefore, overcome this short duration of high soil resistance. Such factors should be taken into consideration while designing new tillage tools.

Cereal grains are subjected to physical forces produced by agricultural machinery during and after harvest. The resulting physical damages have biological consequences such as reduced germination and yield. Damages may be minimized by adjusting equipment to take into account the physical resistance of grain to mechanical and dynamic loading. This paper describes methods for evaluating grain-to-ear binding force and grain physical resistance and presents the results for barley, rye, spring wheat and winter wheat varieties. Results of research on relationships between physical forces and biological effects on varieties of spring wheat and winter wheat are also presented and discussed.

Mechanical handling of fruits from harvesting to marketing has often led to excessive bruises such that few of them make it to the fresh market. This has, therefore, called for a new engineering approach to determine the parameters which influence the firmness of fruits in order to reflect the optimum maturity for mechanical harvesting and post harvest handling. This paper reviews both the destructive and non-destructive techniques for determination of mechanical properties that influence the firmness of fruits. Mathematical equations relating fruit parameters like the Modulus of Elasticity, Poisson's ratio, bruise volumes, impact forces, energy absorbed by the fruit, fruit deformation and contact stresses are presented. Also, recent techniques used in mechanical handling of fruits to minimize bruises are addressed.