Comparison of methods for determining cloddiness in seedbed preparation

To determine the optimum degree of roughness of a seedbed, it is necessary to identify parameters that can quantify cloddiness. This is necessary not only within experimental boundaries, but also to check the quality of work and to objectively adjust implements. In this study, the degree of cloddiness of seedbeds was evaluated using four different methods: the sieve method; image analysis; the standard deviation of the heights defining the soil profile; and counting, in the field, clods with diameter > 40 mm. The degree of correlation between the results obtained by the different methods was also evaluated. The method based on image analysis was well correlated to the sieve method (r2 = 0.81) and can be used as an alternative for determining seedbed cloddiness . The standard deviation of the heights defining the profile can be correlated, with a fair approximation (correlation to sieve method r2 = 0.63), to the degree of cloddiness of the seedbed, although this is also influenced by factors not linked to clod size (oriented roughness). The method based on counting clods with a diameter > 40 mm is a simplification of the method based on image analysis; though its correlation to the sieve method is lower (r2 = 0.53), it lends itself to field application at the stage of adjusting implements. Furthermore, given it's simplicity, it appears to be suitable for use by extension services to objectively determine seedbed cloddiness and avoid excessive pulverising of soil. The type of implement affects, sometimes clearly, the relations between the various indexes and these variations can be explained by the way the implements operate. In particular, comparison between the sieve and the image analysis demonstrates the different distribution of clods in the vertical profile of the tilled layer; the comparison between image analysis and soil height standard deviation singles out the roughness component not caused by the dimensions of the clods. Finally an analysis of indexes technical aspects under field conditions is reported.