Effect of organic matter on the growth,nodulation, and nitrogen fixation of soybean grown under acid and saline conditions

Abstract

A field experiment was conducted to examine the effects of two organic materials (Bark and Tenporon composts) on the growth, nodulation and nitrogen fixation (measured as acetylene-reducing activity) of soybean plants (Glycine max L.) under acid and saline conditions. These organic materials were incorporated into acid and saline (induced by irrigating the soil with a NaCl solution) soils at 4% rate of application.

These composts tended to improve nodule formation in soybean under acid and saline conditions, especially in the plants treated with Bark compost. Acetylene-reducing activity was significantly (P<0.05) increased by these composts under acid condition.

These composts also tended to improve shoot growth under acid and saline conditions, presumably due to the improvement of the soil moisture status of the soils and nutrient uptake. These results suggest that the growth of soybean could be improved by the application of organic matter under acid and saline conditions.     

Evaluation of maturity of poultry manure compost by phospholipid fatty acids analysis

To study the influence of the physical properties of compost feedstock on some characteristics associated with maturity, two types of compost were made from poultry manure, rice husk, and rice bran. The bulk density of one type (PMC) was always higher than that of another type (NMC) during composting. In the case of PMC, the change in temperature, decrease in NH₄⁺, appearance of NO₃^–, and increase in germination indices (GI) with Japanese Komatsuna (Brassica campestris cv. Osome) were all more delayed than in NMC. As the composting process progressed, the proportion of branched (iso-, anteiso-, 10Me-) and saturated phospholipid fatty acids (PLFA) [BRANCHED FAMES (fatty acid methyl esters), biomarkers for gram-positive bacteria] gradually increased, then reached plateau. The high proportion of BRANCHED FAMES was maintained over a long storage period. The straight hydroxyl and saturated PLFAs (SOH-FAMES) initially increased, then disappeared with the progress of composting. The increase in BRANCHED FAMES and the decrease in SOH-FAMES were more delayed in PMC than NMC. The day on which the proportion of BRANCHED FAMES reached plateau and the proportion of SOH-FAMES dipped below 2 mol% coincided with the maturity stage based on the changes of physicochemical characteristics and GI. The composition of BRANCHED FAMES showed highly positive and negative correlation with GI and NH₄⁺, respectively. In the case of SOH-FAMES, inverse correlations were observed. This indicates that the proportion of BRANCHED FAMES and/or SOH-FAMES can be used as a tool for evaluating the maturity of poultry manure compost.     

Characteristics of bacteria in the forest soils under natural vegetation

Characteristics of the predominant bacteria isolated in November and May from the forest soils of both dry and wet types under natural vegetation were studied.

Although Gram-negative rods were the most abundant bacteria in both soil types and in both seasons, their contents were less and other bacteria especially spore-forming ones increased in May.

Among Gram-negative rods in the soil of the dry type in November, the most predominant was those with nonchromogenic rods motile with polar flagella which grew in a simple synthetic media containing glucose or p-hydroxybenzoate and ammonium as the sole carbon and nitrogen sources. In May, the ratio of the bacteria which require amino nitrogen or those with more chomplex nutritional requirement increased. In the soil of moderately wet type, the difference in kinds of bacteria between the two seasons was not so clear as that in the dry type.

Most of Bacillus species obtained in these soils were those requiring amino acids or other growth factors among which B. cereus was most abundant.     

Microorganisms in tile forest soils with different vegetation

Characteristic microfloras have been found to exist corresponding to the soil types. In cultivated soil, corynebacteria have been shown to be one of the dominant groups, and In grassland soil has been characterized by pseudomonads (1–3). In contrast, pine forest soil has been shown to contain Bacillus as a dominant genus (4).     

Nitrogen-Fixing Microorganisms in Paddy Soils X

During the study on the distribution of blue-green algae which was carried out to evaluate the practical significance of nitrogen fixation by blue-green algae in the nitrogen economy of paddy soils, some soils, in which the autochthonous algae could not grow vigorously, and as a matter of course, their nitrogen fixation was also Very poor notwithstanding every encouraging treatment such as fertilization by potassium phosphate, adjustment of soil reaction by calcium carbonate or inoculation of a nitrogen-fixing blue-green alga, were found.     

Chemical and bacterial changes in a forest soil percolated with some amino acids and leaf litter extract

Chemical and bacterial changes in the forest soil percolated with glycine and glutamate solution and leaf litter extract were studied.

When the forest soil was percolated with 25 mM glycine or glutamate, it took about 20 days for the number of bacteria to reach the maximum in number and the amino acids to be completely ellhausted, the rate being much slower than that in the cultivated soil. Supplementation of 0.01% yeast extract to the percolate much rnhanced the growth of bacteria and degradation of glycine. In this percolation the metabolic pattern of glycine was comparable to that in the cultivated soil except for the absence of an appreciable amount of nitrate formation.

Growth of bacteria in the forest soil was also rapid when percolated with leaf litter extract and only 3 days were sufficient for reaching the maximum number. Neither ammonia nor nitrate was detected throughout the percolation period and only change observed in the solution was a slight rise in pH.

Characteristics of bacteria enriched in the forest soil percolated will) glycine with and without yeast extract, and leaf litter extract were studied, No one group was dominant in the soil before percolation. Bacteria enriched by glycine were almost occupied with Gram-negative nonmotile rods with rather complex nutritional requirement regarded as Achromobacter, which were characteristically unable to utilize glycine as a sole nitrogen source. When the soil was percolated with glycine supplemented with yeast extract, enriched bacteria were composed of many kinds. The soil percolated with leaf litter extract was occupied with bacteria with simple nutritional requirement, which were regarded as Pseudamonas.