No abstract

The X‐ray diffraction pattern of Nägeli‐treated potato starch was examined and changes in the diffraction pattern of native potato starch were measured for hydrations ranging from 0 to 50%. The fine structure of the diffraction pattern revealed many lines of very weak intensity, superimposed on a “basic structure” with hexagonal unit cell. It is suggested that that a “superstructure” exists in fully hydrated potato starch. A packing arrangement of hydrated potato starch is proposed in which every string of six helical macromolecular chains encloses a cylindrical cavity filled with water structured like cubic ice.

No abstract

Summary Some representative podzol profiles from an Alpine region are described. Their genesis is mainly a function of vegetation and drainage and is analysed by morphological, chemical, and mineralogical methods. The effect of soil management on profile development as governed by recent economic advances has been discussed. When meadows with brown soils that are preserved by careful management are abandoned, heather and bilberries start growing and podzolization processes begin. Illuviation horizons are formed that have a friable consistency when formed in these meadows, but that may be hard and brittle when developed in sandy till with only heather or bilberries. Soil physical processes lead only to a fragmentation of parent rock, whereas pronounced chemical weathering occurring in these soils—decreasing in intensity with depth—produces an active clay fraction, the composition of which is discussed. Chemical weathering was most pronounced under poor vegetation. The higher content of silt in the topsoil can be partly attributed to sedimentation of wind‐blown particles. Frost action leads to sedimentation of fine soil particles on top of larger mineral fragments lying at some depth in a profile.

On calcareous micaschists in the northern Adula Region, Switzerland, brown soils are formed under grasses and herbs at altitudes below 2000 m. Podzols occur below Ericaceae below 2000 m and are formed irrespective of vegetation above this altitude. Calcimorphic soils are not found. Brown soils have a stable clay mineral association of chlorite and mica, while in the A horizons of podzols and in initial podzols alteration of chlorites to smectites occurs.