Shuichi Ishizawa

MICROFLORA OF JAPANESE SOILS : Part 4.Microflora of Paddy Soils

Abstract A characteristic of paddy soils is that they are kept under a water-logged condition during rice cultivation. It seems quite natural to expect that paddy soil harbours a characteristic microflora not common in upland soils. However, few studies have been made on the microflora of paddy soils(1,7). This study was conducted to compare of these paddy soils with those reported in the previous papers(4,5,6).

Studies on microbial population in the rhizosphere of higher plants with special reference to the method of study

Abstract Introduction Many previous investigations, beginning with the observations of Hiltner19, have established the fact that soil in the rhizosphere contains a higher quantity of microorganisms than soil which is not within the influence of the plant root. It has been shown also that the balance between certain physiological groups4,21,43,45, as well as that between morphological types of bacteria or fungi30,50 is changed in the rhizosphere. In addition, Canadian investigators23,34,62) have reported a change in the balance of certain nutritional groups of soil bacteria in the rhizosphere. Two excellent reviews6,22) covering these papers have recently appeared. Since then a number of papers2,7,9,11,13,15-18,25,26,33,36,38-40,48,54,57-60,63) concerning various aspects of the microbial population of the rhizosphere have been published.

Effects of DD, EDB and PCP upon microorganisms and their activities in soil part I effects on microflora

Abstract The extensive use of various insecticides or herbicides makes it desirable to know what influences, if any, such chemicals may exert upon soil microorganisms. The effect of chemicals should be considered not only upon plant pathogenes, but also upon general soil micro-organisms.

STUDIES ON THE NITRIFICATION IN SOIL, WITH SPECIAL REFERENCE TO THE POPULATION OF NITRIFIER : Part 2 Nitrogenous Fertilizers and Their Effectiveness as Substrate for Nitrification

Abstract It is certain that the nitrification in soil differs from that in culture solution. But the study in culture solution is neccessary for a better understanding of nitrification. Although the perfusion technique, introduced first by Quastel and his has contributors1)2), has been a very useful tool and has conntributed much to the problem of nitrification, it must not be overlooked that it produces a specific condition. Among the information given them. the most attractive was the descrition of the state of NH4 + in soil and its nitrication3). According to their results, the nitrifier in eres to the soil particle and nitrifies NH4 +, not in the solution, but is exchangeably absorbed there. In their experiments, it was proved ht at the rate of nitrification was dependent upon the base exchange capacity of soil column and that the addition of CaCl2 to the perfusate decreased the nitrification.

EFFECTS OF DD, EDB AND PCP UPON MICROORGANISMS AND THEIR ACTIVITIES IN SOIL : PART II EFFECTS ON MICROBIAL ACTIVITY

Abstract In the previous paper (7), the effect of chemicals upon microbial balance in soil has been reported. Since it is a usual phenomenon that an effect on microbial balance brings about the change of metabolism in soil, experiments were simultanuously conducted on the effect of chemicals upon the microbial activity in soil. It seems that not many reports have been concerned with the above aspects on the new chemicals.

COMPARATIVE STUDY ON EFFECTIVE AND INEFFECTIVE NODULES OF LEGUMINOUS PLANTS

Abstract It is well known that nitrogen fixation is mainly dependent upon the combination between rhizobial strain and host plant species, though it is also affected by the environmental condition. The site of association between the host and rhizobia is the root nodule. It is, therefore, quite natural that special attention has hitherto been focused on it. A typical symbiotic relationship is going on in effective nodule, while a parasitic relationship prevails in ineffective one. Between such types of nodules there must be some differences with respect to the inner structure as well as the metabolism in them. Experiments were made to compare the morphological change of rhizobia, the amount and distribution of starch, the kinds of free amino acids in effective nodule with those in ineffective one. To obtain materials, soybean, pea, red clover, and genge (Astragalus sinicus L.) Were used with their own effective and ineffective strains of rhizobia, respectively.

Studies on microörganisms and their activities in soil Part. 1. Change of microflora induced by soil treatment, with special reference to the method of study

Abstract Introduction Joffell described in his book “Pedology” that in the process of weathering, autotrophic organisms grow on the bare surface of rocks and their metabolic products contribute much to the weathering. Treub2) observed also that the surface of volcanic ash was covered by the vigorous growth of algae in less than three years after the eruption of Krakatoa. From these statements it appears evident that microorganisms play an important part through the production of organic matter at the early period of soil formation. As soil-forming-process advances, however, microBrganisms are replaced by the higher chlorophyllbearing plants with regards to organic matter production in land, and they become more important in the decomposition of than in the production of organic matter.

Microflora of Japanese soils: Part 3. Comparison between volcanogenous and non-volcanogenous soils

In the foregoing two parts(4,5) the microflora of volcanogenous and non-volcanogenous soils were reported. In this part comparisons were made on the microflora between two groups of soils and discussions were held on the results obtained.

Studies on the Nitrification in Soil, with Special Reference to the Population of Nitrifier: Part 3 Part played by Soil under Percorating Condition

It is certain that the nitrification in soil differs from that in culture solution. But the study in culture solution is neccessary for a better understanding of nitrification. Although the perfusion technique, introduced first by Quastel and his has contributors1)2), has been a very useful tool and has conntributed much to the problem of nitrification, it must not be overlooked that it produces a specific condition. Among the information given them. the most attractive was the descrition of the state of NH4 + in soil and its nitrication3). According to their results, the nitrifier in eres to the soil particle and nitrifies NH4 +, not in the solution, but is exchangeably absorbed there. In their experiments, it was proved ht at the rate of nitrification was dependent upon the base exchange capacity of soil column and that the addition of CaCl2 to the perfusate decreased the nitrification.

Studies on microörganisms and their activities in soil Part. 2. Virgin and cultivated soil of the same origin

Abstract The nature of soil is modified differently depending upon the artificial condition such as its utilization or management. It is therefore expected that the microbiological characteristic of soil is changed also. Greaves1) and Williams2) reported that the reclamation of virgin soil brought about a change of bacterial count. Suzuki et al3) observed that the kind of fungi differed between a virgin and a cultivated soil and that the vegetative mycelium was numerous in the former than in the latter. On the other hand, according to W aksman and Starkey4), the bacterial count differed depending upon the fertility of soil. Singh5) reported also that the number of fungi and actinomycetes was higher in a fertile than in an infertile soil. Lochhead6), and Lochhead and Chasen studied the bacterial flora of a fertile (long-continued application of manure) and an infertile (no fertilizer for many years) soil and found that a certain difference could be observed when morphological, physiological and nutritional...