斜面急速緑化工法に関する研究 I : タネ吹付工法を中心とする基礎的実験

Abstract

We have found a new method for preventing soil erosion on denuded slopes. The method is the use of a concrete gun which blows a mixture consisting of water, seeds, and fertilizers onto a denuded slope to establish its protective grass cover. For the success of this method, the decisive factor is the retention of water required for germination of seeds. In this respect, we have made a series of experiments on relations between water and germination of grass, with following results. The quantity of water needed for germination varies according to the difference in environmental conditions. If the conditions are the same, each kind of seed shows an inherent germination tendency and a characteristic water-absording curve. At the begining of germination, the greater amount of water is favorable to the growth of seeds, but in the later stage, they grow best in the soil which contains the most adequate amount of but in the water for plant growth. Drought resistance of the seeds lowers with the lapse of time after seeding till a drought. But, since they are hardly cut off from water as their root systems develop, the most dangerous period will be somewhere about 48 hours after seeding if the temperature remains at an adequate degree. Thus the drying of seedbed soil during the germinating period causes the grasses a severe damage. The recovery of growth after a drought was better in the plots which had been given less water than the other. Next, we made an experiment on covering materials over seedbed with the aim of protecting seeds from both erosion and drought. Asphalt emulsion, petrolatum emulsion, soil conditioner like Soilax, and others were tested for the effects. The most effective among these is asphalt emulsion which forms a thin film over the seedbed after sprayed, not permeating the soil, thus preventing a loss of moisture and a possible erosion. Besides it has no injurious wrong effect for the germination and the succeeding growth of grasses.