石灰窒素の林地・苗畑への適用に関する研究

Abstract

We studied on the applications of Ca-cyanamide to forest nursery or planted trees. This study consists of following three main points. I. On the evasion and utilization of the poisonous action of Ca-cyanamide. II. On the fertlizing utility of Ca-cyanamide on the young seedlings and on the methods to increase it. III. On the utilization of Ca-cyanamide for promoting the decay or decomposition of the organic matters. The experiments were made to clarify the points mentiond above from 1957 to 1960. The results of the experiments are summarized as follows. I-1 On the evasion of the poisonous action of Ca-cyanamide. From the experimental results it may be concluded that: 1. Sugi (Cryptomeria japonica D. Don) seedlings are less resistance against poisonous effects of Ca-cyanamide than Hinoki (Chamaecyparis obtusa S. et Z.) or Japanese black pine (Pinus Thunbergii Parl.) 2. The poisonous action of Ca-cyanamide varies according to the soil temperature and other soil conditions. But, its injurious effects can be avoided by waiting for a few days as shown in table 3 from Ca-cyanamide applied to till retransplantation of the seedlings. 3. When Ca-cyanamide is applied for the sake of weeding, insectcide or sterlization at such a rate as present use, it dose not injure the seedlings of Sugi or Hinoki which are transplanted after ten days it was applied. 4. From the point of view of poisonous action it seems more desirable to apply it half or one therd of totol amount of Nitrogen as Ca-cyanamide than to apply it as Ca-cyanamide alone. 5. We may be sure that if Ca-cyanamide is applied with Ca-superphosphate or Pottasium chloride, its injury is so great as not effect it is applied alone. I-2 Utilizations of poisonous action of Ca-cyanamide. 1. Urajiro (Dicranopteris glauca Nakai) and Koshida (D. dichotoma Bernh), which grow thick in west part of Japan, especialy in coast districts, are great obstacles from the view-point of forestry. Not only they directrly, make harder for the silvicutural operations such as weeding, planting, and after-weeding, but also, undirectly, they are disagreeable, making the soil condition worse for supply of water and integration of the organic materials. 2. The main foresting counterplans in shida-areas are, first, to exterminate them, second, to control their rebirth, and then, to quicken decomposition of their rhizome. And at the same time it is important to supply N-fertilizer. As Ca-cyanamide seemed to play these roles, we carried out a few experiments. 3. Ca-cyanamide shows in one to three weeks even when it is applied without mowing away Shida-plants, a remarkable effect of destruction the shida-plants. (see Table 12, 13) Proper quantity of its applications are between 300g and 600g per m2. If Ca-cyanamide applied after mowing away of Shida-plants can control their rebirth in such a small quantity as 200g per m2. 4. It may be safe to say that Ca-cyanamide has an influence upon the moisture condition of soil and circulation of nourishments as well as it lessens the labour of digging planting holes and after-weeding Because it destroys not only Shida plants what is on the ground but also the rhizomes of its. 5. In this experiment Ca-cyananmide applied in May or June showed the before-mentioned effects. And perhaps it shows more remarkable effects if applied in the latter part of August to begining of September, from the experiment measured the amount of regenerated shida or July, when rhizome of Shida-plants are in lowest condition in their Nitrogen content. II. Efficacy of Ca-cyanamide for fertilizer. 1. Ca-cyanamide is even when it is applied alone, more efficacy than non-fertilized condition, both on nursery and forest. See table 16. 2. Effect of Ca-cyanamide can be increased by assorting phosphorous and potassium. 3. As the resource of Phosphorous which is to be assorted with Ca-cyanamide, Ca-supherphosphate is of remarkable efficacy, but Serpentinen-superphosphate is much more available. And then Fused phosphate has also good efficacy. 4. Ca-cyanamide showed remarkable fertilizing efficacy to Sugi, Acacia mollissima and Eucalyptus saligna. III. The efficacy of Ca-cyanamide to decomposition of organic materials. 1. Stems and leaves of Shida are very difficult material to decompose in its natural condition. 2. If we cut its peaces 10 ~ 15cm. in length and mixed them with Ca-cyanamide and then over them up with the soil of nursery 15 ~ 20cm. thickness, its decomposition or decay will be much promoted. 3. From the result of the experiments, we think that the following ratio is suitable: 1, 000g of fresh material of the Shida: 60g of Ca-cyanamide. 4. At the nursery in Shirahama district, it may be allowed to decompose about 3, 000g of Shida per m2 in a year.