竹林の肥培に関する研究 (第1報) : 三要素試験について

Abstract

As the first stage of the studies on fertilizer-management in bamboo forest, we had the three element tests in order to get the fundamental data, and the report consists of two investigations. The preparatory test with SASA (Pleioblastus pubescens Nakai) was made in the pot of 1 m. in diameter and the practical test was made in the MADAKE forest (Phyllostachys reticulata) consisting of 100 m2 a plot. Both of the investigations were classfied as follows: -- Lot 1 Complete. (three elements plot) Lot 2 No nitrogen. (nitrogen lacking) Lot 3 No phosphorus (phosphorus lacking) Lot 4 No potash. (potash lacking) Lot 5 No manure. Three elements have been supplied as ammonium sulphate, superphosphate of lime and potassium sulphate. The results of the test with SASA for the past two years were as follows: -- 1. The yields of the fresh matter weight over the ground (stems, branches, leaves) were the most in the complete plot, the yield in the other plots being remarkably low. The yields were shown as follows in index number; the complete plot 100, the no potash plot 53, the no phoshorus plot 41, the no manure plot 35 and no nitrogen plot 28. The yields in the no nitrogen plot were lower than that in the no manure plot. 2. The yields of the fresh matter weight under the ground (roots, rhizome) were the most in the complete plot. The yields in the other plots decreased in the following order: the no potash plot 54; the no phosphorus plot 44; the no nitrogen plot 44; the no manure plot 39. These results showed that the growth in the complete plot was very superior and in the other plots they were about 1/2 or 1/3 of the former, in the no nitrogen plot, in the no phoshorus plot and in the no manure plot were especially inferior. Therefore, we knew that the three elements were very effective elements to the growth of SASA. 3. The colour of leaves were changed by the influence of each management. 4. Analysis of the harvest showed that the nitrogen (N) content was about 2% in the leaves, about 0.5% in the stems and the branches, about 0.5-0.19% in the rhizome and root and the P2O5 content were about 0.2%, 0.1% and 0.2%, and the K2O content were 0.4-0.7%, 0.4% and 0.6-1.5%. These elements content were higher in the plot applied with these elements than in the plot not applied. 5. Percentage of absorbance value of the three elements in each part of SASA was as follows: -- N----in the rhizome and root was about 40%, about 20% in the stems and branches, about 40% in the leaves. P2O5----similarly, 60%, about 20%, about 20%. K2O----70%, 15%, 15%. The absorbance values of nutrient were especially very high in the rhizome and root. The results of the test for the past two years in the MADAKE forest were as follows: -- 1. Fertilizing effects on the yield were observed plainly in the first year after fertilizing, and in the second year the effects were observed more remarkably, and the yields (number of SOKU) were the most in the complete plot. The index numbers of the yield were as follows: -- the complete plot----100 the no potash plot----85 the no phosphorus plot----65 the no nitrogen plot--60 the no manure plot----39 2. Fertilizing effect was remarkable on the number of new bamboo sprouting, but the diameter increment was not remarkable. 3. The soil used in this experiment was analyzed after two years since fertilizing, and the results show that soil acidity in the manure plot was a little stronger than the no manure plot. 4. The results of this test agreed with that of the former test.