• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.16-22
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• 1997

Determination of N mineralization and nitrification potentials of selected Piedmont soils of North Carolina requires a better understanding of the influences of incorporated plant residues. The net N mineralization and nitrification were significantly influenced by the soil types and by plant species. The net N mineralization and nitrification of soils mixed with plant residues were consistently increased with successional incubation periods. The net mineralization and nitrification ranged from $9.77{\mu}g/g$ to $143.80{\mu}g/g$, and from $5.31{\mu}g/g$ to $145.66{\mu}g/g$ during the incubation periods, respectively. The net N mineralization was more influenced by NO3-N than by NH4-N. Overall, the greatest proportions of net N mineralization and nitrification occurred in Chewacla and Wehadkee and lowest in Enon and Mecklenburg. For the plant residues, the net N mineralization and nitrification were observed to be lowest in corn and highest in soybean. In a low-input agricultural systems, soybean may be planted as cover crop which may improve the nitrogen status of selected Piedmont soils of North Carolina.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.431-437
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• 2015

Recently, assessment of nitrogen balance has been required for environmental agriculture. Nutrient management using organic matters in farmlands has been strongly required as a means of extending resource-cycling agriculture and reduction of nitrogen balance. Organic matters-derived nutrients and soil-available nitrogen should be necessarily considered to manage nutrient balance in soil-plant system. In this study, we reviewed the amount of N supply according to types of organic matter such as livestock compost and green manure in arable land. In case of applied livestock compost in soil, nitrogen mineralization was influenced by nitrogen amount of livestock manure and mixed materials. And nitrogen mineralization of green manure in arable land was influenced by types of crop and return period of green manure because of change of C/N ratio. Also, nitrogen supply by organic matter in arable land can be changed by environmental factors such as temperature, moisture in soil. Therefore, nitrogen supply according to C/N ratio of organic matter and analysis method for estimation of soil nitrogen supply availability should be evaluated to set up the nutrient management model.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.3
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• pp.196-201
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• 2018

Soil is the main nitrogen (N) provider for plants but N in soil is not all available to advanced plants. Mineralization is a critical biological process for transferring organic N to inorganic N that can be used by plants directly. To investigate the effect of different levels of soil temperature and water content to soil mineralization, a field experiment was established on three different sites (A, B and C). We measured soil temperature, moisture and electrical conductivity once daily after swine slurry application. Average soil moisture and temperature in site A is the highest among three sites (40.9% and $9.7^{\circ}C$, respectively). Following is in site C (37.3% and $9.6^{\circ}C$) and the lowest is in site B (28.0% and $9.0^{\circ}C$). Ammonium N (NH4+-N) and nitrate N (NO3--N) were determined on the first and fifth day after treatment. Compared with site B and C, site A always had the highest soil total N content (1.54 g N kg-1 on day one; 1.22 g N kg-1 on day five) and highest NO3-- N content (93.18 mg N kg-1 on day one; 16.22 mg N kg-1 on day five) and a significant decrease on day five. Content of NH4+-N in site B and C reduced while in site A, it increased by 6.7%. Results revealed that net N mineralization positively correlated with soil temperature (P<0.5, $r=0.675^*$) and moisture (P<0.01, $r=0.770^{**}$), suggesting that to some extent, higher soil moisture and temperature contribute more to inorganic N that can be used by plants.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.1
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• pp.29-37
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• 1977

The mineralization of soil nitrogen, amino acid composition of acid hydrolizable organic nitrogen of four Korean soils were investigated in comparison with four Japanese (Hokuriku district) soils which is similar in nitrogen content but different in characteristics of clay minerals. The mineralization rate and pattern were quite different between Korean and Japanese soils; Korean soils were low in amount of mineralized nitrogen but porduced much ammonium nitrogen during the later stage of incubation. In Korean soils the ratio of acid hydrolizable nitrogen to total; especially ${\alpha}$-amino nitrogen and hydrolizable ammonium nitrogen were low while hexosamine content was considerablly high (greater than 10%) In all soils the amount of mineralized nitrogen showed significant positive correlation with ammonium nitrogen and ${\alpha}$-amino nitrogen in acid hydrolizate. The amino acid composition of acid hydrolizate of paddy soils showed higher in basic amino acids and lower in acidic amino acids than those of up land soils (humic volcanic ash soil) from both countries. Alanine content was low in Korean soils. Proline showed increasing trend with nitrogen content but aspartic acid decreasing.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.33-40
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• 2014

This study were conducted to evaluate the N mineralization and nitrification rates and to estimate the losses of total carbon and nitrogen by runoff water in soils cooperated with organic composts and bio-char during corn cultivation. For the experiment, the soil texture used in this study was clay loam, and application rates of chemical fertilizer and bio-char were $230-107-190kg\;ha^{-1}$($N-P_2O_5-K_2O$) as recommended amount after soil test and 0.2% to soil weight. The soil samples were periodically taken at every 15 day intervals during the experimental periods. The treatments were consisted of cow compost, pig compost, swine digestate from aerobic digestion system, and their bio-char cooperation. For N mineralization and nitrification rates, it was shown that there were generally low in the soil cooperated with bio-char as compared to the only application plots of different organic composts except for 47 days after sowing. Also, they were observed to be highest in the application plot of swine digestate from aerobic digestion system. For loss of total carbon by run-off water, it was ranged from 1.5 to $3.0kg\;ha^{-1}$ in the different organic compost treatment plots. However, Loss of total carbon with bio-char could be reduced at $0.4kg\;ha^{-1}$ in PC treatment plot. Also, with application of bio-char, total nitrogen was estimated to be reduced at 4.2 (15.1%) and $3.8(11.8%)kg\;ha^{-1}$ in application plots of pig compost and swine aerobic digestate, respectively.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.805-819
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• 2017

The study was carried out to develop a mathematical model for evaluating the effect of organic fertilizers in organic rice production systems. A function to simulate the nitrogen mineralization process in the paddy soil has been developed and integrated into ORYZA2000 crop growth model. Inorganic nitrogen in the soil was estimated by single exponential models, given temperature and C:N ratio of organic amendments. Data collected from the two-year field experiment were used to evaluate the performance of the model. The revised version of ORYZA2000 provided reasonable estimates of key variables for nitrogen dynamics and crop growth in the organic rice production systems. Coefficient of determination between the measured value and simulated value were 0.6613, 0.8938, and 0.8092, respectively for soil inorganic nitrogen, total dry matter production, and rice yield. This means that the model could be used to quantify nitrogen supplying capacity of organic fertilizers relative to chemical fertilizer. Nitrogen dynamics and rice growth simulated by the model would be useful information to make decision for organic fertilization in organic rice production systems.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.253-258
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• 2005

It is necessary to determine a nitrogen supplying capacity (NSC) of soil for sustainable agriculture. NSC has been decided by directly detecting N mineralization potential (NMP) and inorganic nitrogen or by indirectly approximating from organic matter and chemical properties of soil. NMP is best method for NSC but it takes long period. A study was conducted to find a short-term incubation method using pepsin through 1) determining NMP of 3 upland and 3 paddy soils, 2) establishing analytical condition of pepsin digestion by comparing to NMP, 3) validating with relations to N requirements for maximum yield of rice. NMPs of 6 soils were ranges from $63mg\;N\;kg^{-1}$ to $156mg\;N\;kg^{-1}$. The pepsin digestion method of soil nitrogen was established by determining amino nitrogen from digesting 5 g of soil for 30 minutes by 0.02% pepsin. This method was so highly correlated with a maximum rate of nitrogen fertilizer that it could be used for determining NSC in paddy soil.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.60-66
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• 1984

Immobilization and mineralization of the tracer nitrogen $^{15}(NH_4)_2SO_4$ applied in submerged soil condition with compost and rice straw to coarse loamy and clay soils were studied at different amounts of applied nitrogen. About 90-, 60-, and 50% of added nitrogen were immobilized at the 10 days of incubation when 0.8-, 1.6-, and 2.4mg of fertilizer nitrogen were added with compost and rice straw in both of coarse loamy and clay soils, respectively. Especially, more pronounced immobilization took place in coarse loamy soil than clay soil. Results obtained from nitrogen fraction showed that the mineral nitrogen was increased with addition of rice straw in clay soil than coarse loamy soil. The amount and index of aminosugar-N and humin-N were variable between soil series and organic matter. Especially, more pronounced amounts of amino acid-N and unknown-N were observed with application of rice straw in coarse loamy soil and compost in clay soil, respectively.

• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.419-427
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• 1999

To clarify the soil N dynamics, the relationship between soil N and vegetation recovery after volcanic eruptions was investigated in two stands dominated by black locust(Robinia pseudo-acacia L.) on volcano Mt. Showa-Shinzan, northern Japan, from August 1999 to July 1996. No significant differences were observed between the two stands with respect to soil chemical properties and soil extractable N. At both stands, total N concentration were high in spring and declined through the summer and fall. The peaks in concentrations of extractable $NH_4{^+}$ and $NO_3{^-}$ occurred in July at both stands. $NH_4{^+}$ mineralization showed a conspicuous peak in June and July throughout the study period. Extractable $NO_3{^-}$ concentration and nitrification rates at the two stands during the study period were relatively high. Negative values for $NH_4{^+}$ mineralization at both stands were found in August. Extractable $NH_4{^+}$ and $NO_3{^-}$ concentrations were correlated positively with soil organic matter, and nitrification rates were controlled by $NH_4{^+}$ mineralization and extractable $NH_4{^+}$ concentration at both stands.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.124-132
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• 2019

BACKGROUND: Silver grass (Miscanthus sinensis) No. 1 was developed for production of bio-ethanol, and for the purpose the silver grass growing sector was established in Geumgang basin, Iksan, Jeonbuk, in 2011. However, the other application potentials except for using as the bio-energy resources should be considered because of the drop in international oil prices. Therefore, there is the necessity of a scientific basis to use the silver grass instead of rice straw as the organic matter source that is used for improvement of soil quality in the plastic film house. METHODS AND RESULTS: The silver grass was applied at 5, 10, 15 and 20 Mg/ha and tilled before the watermelon was planted in the plastic film-house. The control plot was treated with 10 Mg/ha with rice straw, and watermelons have been cultivated for 3 years(2017~2019). Soil aggregation, soil chemistry, and the growth characteristics were investigated, when the watermelon was harvested every year. Soil aggregation levels at the 2nd and 3rd year of watermelon harvest were similar from the plot applied with the silver grass at 5 Mg/ha and the control plot, and increased in the silver grass treated plots with more than 10 Mg/ha. However, there was no statistically significant difference between the plots. The nitrogen mineralization of silver grass in the control plot tended to be similar to the 5 Mg/ha plot, but the silver grass treated plots with over 10 Mg/ha showed low nitrogen mineralization. Soil EC on harvest stage was proportional to the applied mass of the silver grass, but pH was in inverse with the applied mass. Soil organic matter content, available phosphate, and exchangeable cations increased with the continued use of silver grass. Watermelon weight found to be the best on more than 15 Mg/ha of silver grass, and the sugar content was highest when 10 Mg/ha was treated. CONCLUSION: The use of the silver grass at 10 Mg/ha annually as the organic source was effective in replacing rice straw while growing fruits and vegetables on the plastic film house.