Togoro Harada

Factors affecting immobilization and release of nitrogen in soil and chemical characteristics of the nitrogen newly immobilized: I. Effect of Temperature on Immobilization and Release of Nitrogen in Soil

Abstract Usually, immobilization and release of nitrogen in soil are going on continuously and concurrently, whereby the nitrogen of the decomposing system is transformed steadily from inorganic to organic state by immobilization and back from organic to inorganic state by decay and mineralization. The driving agents of this turnover are soil microorganisms, C/N ratio, temperature, moisture, pH etc., and the energy needed to keep this cycle running derives from decomposable organic compounds added to soil in the forms of plant residues and excretions of roots and stored in the form of soil organic matter.

EFFECT OF NITROGEN SOURCES ON THE CHEMICAL COMPONENTS IN YOUNG PLANTS

Abstract Nitrogen nutrition has great influences not only on the yields, but also on the chemical components of the plants. Nitrate nitrogen is generally found to be superior to ammonium nitrogen as the nitrogen source for higher plants (1). As reported in the previous paper (2), young plants of sugar beet grown with the culture solution containing a high level of ammonium nitrogen developed the symptom of ammonia toxicity. To make clear the mechanism of ammonia toxicity, comparative studies on the absorption and the assimilation of ammonium- and nitrate-nitrogen in higher plants at young stages of growth were carried out.

Drying effect on mineralizations of microbial cells and their cell walls in soil and contribution of microbial cell walls as a source of decomposable soil organic matter due to drying

Abstract 1) The mineralization of several kinds of microbial cells added to soil were accelerated considerably by the drying effect. 2) When microbial cells were roughly divided by mechanical procedure into two parts, i.e., cytoplasmic and cell wall substances, and separately added to soil with or without drying previously, the former was mineralized very quickly both with and without drying previously and its mineralization was not accelerated by the drying effect. The latter without drying previously was mineralized rather slowly, and the latter with drying previously was mineralized very quickly and remarkably. Furthermore, the former with and without drying previously left hardly any residual matter in soil, but the latter without drying previously left considerable residual matter because of making a complex resistant to microbial decomposition with colloid materials such as clay minerals and humus, and mineralization of the residual matter was remarkably accelerated by the drying effect. 3) From the...

Factors affecting immobilization and release of nitrogen in soil and chemical characteristics of the nitrogen newly immobilized III. Transformation of the nitrogen immobilized in soil and its chemical characteristics

Abstract The immobilization and release process of nitrogen and the chemical characteristics of newly immobilized-, subsequently released-, and residual-N were studied in soils receiving KNO3 labelled with 15N together with glucose, straw, and cellulose. Immobilization of nitrogen proceeded rapidly and reached its maximum at incubation periods of 3 days to 8 weeks or more, varying with the kind of carbon sources added. Following the maximum tie-up of nitrogen a rapid release began. After 20 weeks the immobilized nitrogen was released at a considerable rate for each carbon source. At the period of maximum immobilization of nitrogen added to soil there was a clear difference in the percentage distribution of various forms of organic nitrogen between applied-N and native-N. The former was higher in amino acid N and unidentified N and lower in nonhydrolyzable N than the latter, and almost the same in hexosamine N and ammonium N as the latter. With regard to all carbon sources the principal form of organic nit...

Factors affecting immobilization and release of nitrogen in soil and chemical characteristics of the nitrogen newly immobilized IV. Chemical nature of the organic nitrogen becoming decomposable due to the drying of soil

Abstract This study deals with the effect of air-drying or oven-drying a soil and remoistening it on the flush of decomposition of soil organic nitrogen and with a comparison of the chemical nature of the nitrogen mineralized between the newly immobilized nitrogen in a soil receiving glucose and KNO3 labelled with 15N and the native organic nitrogen in the soil. Mineralization of soil organic nitrogen was remarkably accelerated through the effects of both air-drying and oven-drying, and the effect was much greater in the latter than in the former. The immobilized-N was made much more susceptible to mineralization than the native-organic N through the effect of air-drying or oven drying. In the course of mineralization of the native-organic N, air-drying enhanced the decrease of amino acid N, in particular after 6-weeks incubation. Also, oven-drying intensified the decrease of all the forms of N for the same incubation periods; the decrease was most remarkable in the forms of amino acid N, unidentified N, ...

Studies on the environmental conditions controlling nitrification in soil: I. Effects of ammonium and total salts in media on the rate of nitrification

Abstract It is well known that the loss of nitrogen from the cultivated field principally occurs in the following two ways: (a) denitrification of nitrate, (b) leaching down of nitrate by percolating water. The problem of nitrification in soil is very important in connection with the efficient use of nitrogenous fertilizers applied to both the paddy- and the upland-field.

Relationship between an accumulation of soil organic matter becoming decomposable due to drying of soil and microbial cells

Abstract The purpose of this experiment is to make clear the relationship between an accumulation of soil organic matter becoming decomposable due to drying of soil and microbial cells. The results are summarized as follows: 1) The accumulation of soil organic matter becoming decomposable due to drying occurred in the decomposition process of organic matter applied to soil, and its quantity clearly increased with an increase of microbial cells. Further, the accumulation increased in company with an increase ofreimmobilization during the decomposition process of organic matter applied to soil. 2) The accumulation of the decomposable soil organic matter was clearly recognized during the decomposition process of microbial cells in soil. The accumulation rate was higher in newly immobilized organic matter of Boil than in native soil organic matter. 3) It was suggested that microbial cells and their cell walls considerably contribute as a source of the decomposable soil organic matter.

Characterization of the organic nitrogen becoming decomposable through the effect of drying of a soil

Abstract Numerous experiments (1, 9, 13, 16, 20, 23) have been reported that drying causes a flush of decomposition of soil organic nitrogen. The magnitude of the flush depends on the pF value at which the soil was dried (9), and the higher the pF value, the larger the magnitude of the flush.

Chemical fractions of organic nitrogen in acid hydrolysates given from microbial cells and their cell wall substances and characterization of decomposable soil organic nitrogen due to drying

Abstract 1) The major part of organic nitrogen fractions in acid hydrolysate which is mineralized through the decomposition process of cells of B. subtilis in sand for 2 weeks was the form of amino acid N, but the form of amino sugar N was hardly mineralized. Their cytoplasmic substances were mineralized quickly, but their cell wall substances comparatively slowly. When the latter, however, was pretreated with ultrasonic or oven-drying treatment, their mineralization was accelerated. The mineralization rate of the form of amino sugar N was remarkably high. 2) The major part of the decomposable organic nitrogen fractions due to the ultrasonicating or oven-drying effects in acid hydrolysates given from microbial cells and their cell wall substances was the forms of amino acid N and amino sugar N. The accelerating effect of oven-drying pretreatment on the mineralization of the form of amino sugar N was larger than that of ultras on icating pretreatment under this experimental conditions. 3) The amino acid co...

Studies on the organic nitrogen becoming decomposable through the effect of drying a soil

Abstract Numerous experiments (2, 7, 9–14,16) have been reported that drying a soil and rewetting it results in a flush of decomposition of soil organic matter and a flush of ammonium and then of nitrates. And if the soil is taken through a number of such cycles of drying, rewetting and incubation, the amount of nitrogen to be mineralized falls off slowly as the number of cycles through which it is carried increases. The magnitude of the flush is larger in lowland soils than in upland ones. Among lowland soils it is largest in the ill-drained paddy. In rough figures, abut 10 per cent of the organic nitrogen is decomposed through one cycle of drying and rewetting in the ever-flooded paddy in Japan. No completely satisfying reason can yet be given for this flush of decomposition, nor is it known what fraction of the organic matter is involved.