• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.188-190
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• 2000

We explored changes in soil nitrogen (N) availability in a thinned (control, light, moderate, and heavy thinning) Larix leptolepis plantation determined by using ion exchange resin bags. Nitrogen availability varied among measurement periods, however, total available N (ammonium plus nitrate) concentrations did not change significantly in the 1 year since thinning. We found higher N availability in summer and fall than in winter.

• The Korean Journal of Ecology
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• v.15 no.3
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• pp.297-309
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• 1992

The growth of digitaria adscendens and eleusine indica, annual weeds common in japan, was experimentally analyzed under varying untrient conditions. compared with e. indica, d. adscendensshowed a higher the two under high nitrogen availability. Higher net assimilation rate(nar) in d. adscendens than e. india was responsible for high RGR in D. adscendens under the low nitrogen availability. The different of NAR in the two species was induced not by leaf nitrogen content but by nitrogen use efficiency. Under unfertilized conditions nitrogen uptake rate(nur) was greater in d. adscendens than e. indica. Specific absorption rate in two species was similar, but root mass was greater in d. adscendens than e. indica.d. adscendens allocated more dry matter to roots than e. india earlier stage of seedlings. The contributed to higher rot mass and in turn resulted in higher nur in d. adscendens than that in e. india. It is concluuded that the larger allocation of dry matter to roots at early seedling stage in d. adscendens plays an important role in obtaining nitrogen for the continuation of growth under low nitrogen availability.

• KSBB Journal
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• v.13 no.4
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• pp.391-398
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• 1998

The effect of culture medium copper availability on the specific growth rate(${\mu}$) and carbon conversion efficiency (CCE) was sutided for an obligatory methanotroph Methylosinus trichosporium OB3b under various combinations of carbon and nitrogen sources. Methane or methanol was used as a carbon source, and nitrate or ammonium was used as a nitrogen source. Medium copper availability determined the intracellular location or kind of methane monooxygenase (MMO), cell-membrane (particulate or pMMO) when copper was present and cytoplasm (soluble or sMMO) when copper was deficient. When methane was used as a carbon source, copper-containing medium exhibited higher ${\mu}$ and CCE than copper-free medium regardless of the kind of nitrogen source. When methanol was used as a carbon source, however, the effect of copper disappeared. Ammonium gave the higher ${\mu}$ and CCE than nitrate for both methane and methanol. Those observation suggest that there exist an important difference in energy utilization efficiency for methane assimilation between sMMO and pMMO.

• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.242-248
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• 2001

Changes in land-use can affect soil organic matter content and fertility. We compared total soil carbon and nitrogen concentrations, soil respiration, and nitrogen availability under three land-use types in central Korea; conversion of old rice field to natural willow-maple (Salix-Acer) forest, conversion of old field to artificial Korean pine (Pines koraiensis) forest, and indigenous oak (Quercus spp.) forest. After 20 years of fallow the area of rice field conversion to forest had higher soil carbon and nitrogen concentrations in the soil depth of 0-10cm and 10-20cm than the areas of field conversion to Korean pine forest and indigenous forest. In general, soil carbon and nitrogen concentrations decreased with soil depth. Organic matter accumulation as a balance of input and decomposition seemed to be higher in the soil of previous rice field, and carbon and nitrogen accumulation was largely confined to the topsoil. Soil respiration rates were greatest at the area of rice field conversion to forest, and appeared to be related to soil carbon and soil moisture. Soil nitrogen availability measured by the ion exchange resin bag method differed significantly among land-use types; soil inorganic nitrogen ($NH_4{^+}+NO_3{^-}$) and ammonium availability were highest in the soil under indigenous oak forest followed by conversion of old field to artificial Korean pine forest and conversion of old field to natural willow-maple forest.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.979-982
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• 2003

Two rapeseed meal samples (Sample A, hybrid 5900 and sample B, double low rapeseed No.4) obtained from China and one Canola meal sample obtained from a local crushing plant in Canada were used to investigate the amino acid degradability of rapeseed/Canola meal in rumen and amino acid digestibility of ruminal incubation residues by precision-fed rooster bioassay. Results show that in ruminal incubation the degradation rate of non amino acid nitrogen in crude protein is higher than that for amino acid nitrogen in crude protein, the results also suggest that the degradation rate of amino acid nitrogen in Chinese rapeseed meal sample B was lower than that for Canadian Canola, but that in Chinese rapeseed meal sample A is much close to that for Canadian canola meal. For all amino acids the digestibility of the bypass or residual protein as measured by the precision-fed rooster bioassay tended to be lower for Chinese rapeseed meal sample A than for sample B or Canadian canola meal which had similar digestibility values. However following a calculation of total amino acid availability, involving the digestibility of amino acids in the rumen and rooster bioassay the results are less contradictory. Results indicated that in traditional roasting-expelling process, heat treatment, especially dry heat treatmeat could decrease amino acids degradability in rumen of rapeseed/canola meal, but also may decrease total availability of amino acids of rapeseed/canola meal.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.1
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• pp.159-164
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• 1992

The present study was done to examine whether inoculated and established bacteria in the digestive tract of germ-free (GF) chickens affect growth performance, energy availability, nitrogen utilization and neutral detergent fibre (NDF) digestibility of the host bird fed a high-fibre diet. Gnotobiotic (GB) chicks were made from GF birds by co-inoculating with Ruminococcus albus, and Staphylococcus warneri, only the latter of which was established in the chicken gut. No difference was detected among conventional (CV), GF and GB birds in body weight gain, food intake or food efficiency from 7 to 21 d of age. The amount of nitrogen retained was larger in CV than in GF and GB chicks. DE and ME values of the diet and NDF digestibility were higher in CV birds than in GF and GB counterparts. It was concluded, therefore, that the established bacterium S. warneri did not give any beneficial effects on the host bird as judged by growth performance, energy availability, nitrogen utilization, and NDF digestibility.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.358-365
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• 2019

We measured the body composition, including bone mineral density (BMD) and food resource availability using dual energy X-ray absorptiometry and the carbon and nitrogen stable isotope ratios of body condition of 4 anuran species(Hyla japonica, Glandirana rugosa, Pelophylax nigromaculatus, Lithobates catesbeianus) in South Korea. Additionally, the carbon and nitrogen stable isotope ratios were employed to determine the food resource availability of anurans. We figured out the relationship between the body composition, including BMDs and food resource availability. The body composition and BMDs did not differ between male and female while there was difference among the species. Food resource availability and BMDs were the highest in L. catesbeianus, the lowest in H. japonica. BMDs tended to increase with higher food resource availability. Body composition and BMDs, which represent the body condition of an individual, can be used as an ecological indicator to assess the stability of the habitat of anurans.

• Journal of Plant Biology
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• v.22 no.3
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• pp.63-69
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• 1979

The plant growth and net production, the nitrogen uptake and recycling, the nitrogen mobility and allocation to each organ, and the nitrogen utility from the Italian rye grass field during the population development were analyzed in comparison with different clipping treatments. The maximum dry matter standing crop and nitrogen quantity of harvest increased significantly, however, the annual amounts of dry matter and nitrogen assimilation showed little variations with increasing clipping frequencies. Plants treated with frequent clippings allocated relatively more nitrogen to leaves and less to roots during the experimental period. The amount of recycling of nitrogen decreased considerably due to frequent clippings. The annual averages of nitrogen utility indices changed in inverse relation to the nitrogen availability; such as 63, 58, 44 and 35 for C, A, M and J plots, respectively.

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.191.1-191
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• 1995

No Abstract, See Full Text

• Environmental Engineering Research
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• v.15 no.3
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• pp.157-161
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• 2010

Forest soils are often nitrogen-limited, and nitrogen input to forest soils can cause substantial changes in the structure and functions of a soil ecosystem. To determine the effects of nitrogen input on methane oxidation and the microbial enzyme activities, manipulation experiments were conducted using nitrogen addition to soil samples from Mt. Jumbong. Our findings suggested that the addition of nitrogen to the soil system of Mt. Jumbong did not affect the microbial enzyme activities. Conversely, the addition of nitrogen affected the rate of methane oxidation. Inorganic nitrogen in soils can inhibit methane oxidation via several mechanisms, such as substrate competition, toxic effects, and competition with other microbes, but the inhibitory effects are not always the same. In this research, seasonal changes were found to produce different inhibitory factors, and these different responses may be caused from differences in the methantrophic bacteria community structure.