Studies on the Pulling Force of Root Vegetables (4)

Analysis of Effective Factors on the Pulling Force of Root Vegetables

Abstract

Two kinds of root vegetables (radish and carrot) cultivated in three kinds of fields were prepared for discussing the effective factors on the pulling force of root vegetables. The various surface of main roots (3-236cm²) were given by the different sowing date.
From the results of experiments, the relationship between the pulling force (F) and the surface area of main root in soil (S) was expressed aproximately with a linear formula, F=aS+b, for various surface areas. The coefficient a in this formula was changed depending upon the soil properties and root vegetables.
Adhesion and cohesion were estimated for clarifing the effective factors on the coefficient a from the results of measurements of the moisture content and penetrating resistance. Adhesion and cohesion were considered to theoretical formula for the pulling force, f=1/2(K_aa+K_cc). The theoretical pulling force was calculated from f and S. The relationship between the theoretical and the measured pulling force was investigated. From the results of investigation, it was clarified that the pulling force was affected by the difference of the vertical distribution of adhesion and cohesion, rather than the difference of soil properties and kind of root vegetables.
It was estimated (from these results) that the theory discussed in the previous reports was signified as the basic rule on the pulling force of root vegetables.