What kind of information can be extracted from manually segmented two-dimensional sections of soil macrostructure?
Abstract
The effect of heavy agricultural machinery upon soil macrostructure was investigated by several methods complementing each other. One of them was the evaluation, both qualitative and quantitative, of thin impregnated soil sections of the size about 60 x 80 mm. The quantitative evaluation was based on manually drawn contours of soil pores (≥ 70 microns) on a sheet of graph paper onto which the magnified image (15 x) of the soil section was projected using polarized light. The quantification consisted in measuring the intercept lengths in the pores, using systems of parallel testing lines. Some sample statistics of the intercept length distribution were related to other soil properties of mechanical and hydraulic nature; at the same time, the morphometric data yielded supplementary information about the soil macropore structure that could not be obtained in other way. More recently, an attempt at manual re-evaluation of the old images was undertaken in order to explore whether more information can be extracted from them and to suggest algorithms for their automated processing. Because of the lacking spatial information, the effort was focused on evaluating the planar images as such. Anisotropy was not considered. Additional information is contained, in particular, in the distribution of the radial contact distances from a random point in matrix to the nearest macropore. On the contrary, the methods based on treating pores as individual particles are probably of little use.