霜柱氷層による作物の断根並にその防除に関する研究 : (第1報) 霜柱氷層形成の樣相

抄録

When it snows little, the soil freezes and under certain circumstances the soil freezing causes the ground to heave. And this heaving of the ground is caused by the formation of the icicle layers. We find the icicle layer gives the most serious injury in winterpassing of the winter crops especially of leguminous plants. The damages suffered directly or indirectly from the formation of the icicle layer are as follows : (1) The breaking of and (2) the lifting of foot. (3) Various physical injuries given apon to the root caused by the heaving of the ground. (4) The drought damage owing to the pit occurred in the ground after melting of the icicle layer. (5) The falling-down of plants. (6) Death of plants. (7) Injuries caused by the water coming from the icicle layer. (8) The soil erosion by the flowing of water which comes from the icicle layer. (9) Washing-out of the root. The soil profile gotten by digging out the frozen soil in winter was as follows (Fig. 1) : The frozen soil is consisted of 3 kinds of so-called concrete layer, pepper-and-salt layer and icicle layer. (2) The icicle layer is as same as the icicle on the surface of the soil and contains no soil. (3) So-called concrete layer is formed directly by the frozen soil. (4) So-called pepper-and-salt layer is the frozen soil containing many thin icicle layers. (5) Problems which concerns the cultivation of crops consist not in the general heaving of the earth but in the changing condition brought about to the relative position of the root and soil which is contacting directly to the root. (6) The process how this underground icicle layer is formed seems as follows : In cold weather, at first the surface soil becomes a concrete layer by freezing. And under the certain content of water and at 0°C, the soil beneath the concrete layer separates its water and forms the icicle beneath the concrete layer. At this time the concrete layer is heaved by the forming action of the icicle layer. This energy of the heaving comes from the latent heat which comes from the water when it becomes the icicle. (7) The frozen soil is a sort of reservoire because the icicle layer is formed of water only.