• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.408-419
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• 2006

A pot experiment was conducted for two years to evaluate the effects of purified Si fertilization combined with $^{15}N$ on the nutrient uptake, plant growth characteristics, and photosynthetic characteristics of rice in water melon cultivated soil. In 2002, plant height was positively affected at 25 DAT (Day After Transplanting) by Si fertilization in 100%N treatment. However, in 2003, plant height at 25 DAT was negatively affected by Si fertilization in low N level but it was reversed in high N level with initial increase of plant height. Tiller number per pot was positively affected by N and Si fertilization level, especially for high N fertilized treatment. Leaf color was positively affected by Si fertilizatlon in no N fertilized pots, however, Si was not effected in 50%N and 100%N fertilized treatments. N harvest index (NHI) increased with increased Si fertilization in no N plots, however it decreased with increasing of N fertilization level. Nitrogen use efficiency (NUE) decreased with increasing of fertilized N but Si fertilization increased NUE in 50%N plots, however, it was not different by the Si fertilization level in 100%N plots. In 50%N+200%Si plots, NUE was greatest with 130 and shoot N content was $16.2g-N/m^{2}$. N content ($g/m^{2}$) in rice plant increased with increasing Si fertilization in no N plots at panicle initiation stage, 50 and 100%N plots at heading stage and all N treatment at harvesting time. This was mostly more efficient in late growth stage than early growth stage. The concentration (%) of P and K increased with increasing N fertilization level at heading and harvesting but it was not significantly different by the Si fertilization treatment except a little decreasing with increasing Si fertilization level at heading. Potassium content was also not significantly related with N fertilization level except increasing with Si fertilization level at panicle initiation stage. Plant Ca content (%) decreased with increasing of Si fertilization at heading stage and Si fertilization increased Ca content at panicle initiation stage and heading stage and it increased with increasing of Si fertilization level. Photosynthetic activity was not directly related with Si fertilization amount, however, Fluorescent factors, Fv'/Fm' and PsII, were positively affected by Si fertilization level. In conclusion, N fertilization in Si 200% fertilized condition should be reduced by about 50% level of recommended N fertilization for rice cropping in green-house water-melon cultivated paddy field. However, improvement of Ps by Si fertilization could not be attributed to Ps activity in the same leaf area but because of increased total leaf area per pot improved fluorescent characteristics.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.278-285
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• 1993

This experiment was conducted to investigate the productivity in permanent orchardgrass grassland according to the urea fertilization levels of 0, 100, 200 kg N/ha and the animal excreta fertilization levels of 0. 40, 80, 160 kg N/ha on the basis of N contents respectively and NO$_3$-N content of the soil. The results were obtained as follows; 1. The productivity of grassland was significantly increased by the increase of the excreta fertilization levels until the urea-N level fertilization of 100 kg/ha but repressed and reduced by the increase to 160 kg/ha level of the animal excreta fertilization at urea-N fertilization level of 200 kg/ha. 2. Averaged seasonal productivity of the animal excreta N was decreased in first and third cutting time and was increased in second cutting time according to the increase of urea-N fertilization. 3. The increase of urea-N and animal excreta N increased the content of crude protein but the fertilization effect of urea-N was higher than that of animal excreta N. 4. The total yield of N was continuously increased at both of the urea-N and animal excreta N but the pure yield of N was decreased according to the increase of N fertilization and showed -63.1 kg/ha at the fertilization of the urea-N of 200 kg N/ha and animal excreta N of 160 kg/ha. 5. NO$_3$-N content of the soil of orchardgrass glassland established one year previously was no difference among the N variety and fertilization levels but was increased to the order of summer, autumn and winter. The highest content of NO$_3$-N was measured in winter with the value of 34.9 ppm.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.106-106
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• 2022

An appropriate amount of nitrogen fertilizer input during rice cultivation is essential for rice growth, quality control, and reduction of greenhouse gases in paddy fields. Therefore, it is necessary to develop a technology that can check whether an appropriate amount of fertilizer is applied in paddy fields. In this study, we tried to derive a method for diagnosing nitrogen fertilization level using spectroscopic diagnosis, physiological analysis, and molecular indicator genes. Nitrogen fertilization treatment was performed in a greenhouse by dividing into five treatment conditions: no fertilization (N0), low fertilization (N0.5), standard fertilization (N1.0), excessive fertilization (N1.5), and double fertilization (N2.0), respectively. Growth characteristics analysis was investigated by nitrogen fertilization conditions and growth stages, and the height of the canopy was analyzed using a laser scanner. Physiological and spectroscopic analyses were performed by analyzing chlorophyll and sugar contents and measuring SPAD and leaf spectrometer on rice leaves. In addition, real-time PCR experiment was performed to check the relative expression levels of several known nitrogen metabolism related genes. These results suggest that spectroscopic techniques can be helpful in diagnosing the level of nitrogen fertilization in rice paddy fields.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.388-392
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• 2016

The objectives of fertilizer recommendation are to prevent the application of excessive fertilization and to produce target yields. Also, optimal fertilization is important because crop quality can be influenced by fertilization. In this study, yields and fertilizer use efficiency of Taro (Colocasia esculenta Schott) were evaluated in different level of NPK fertilization. N, P and K fertilizer application rates were 5 levels (0, 50, 100, 150, 200%) by practical fertilization ($N-P_2O_5-K_2O=180-100-150kg\;ha^{-1}$), respectively. In the N treatment, the yields of Taro tuber were about $33Mg\;ha^{-1}$ from 90 to $360kg\;ha^{-1}$ N fertilization. However, the ratio of tuber to total biomass decreased with increasing N fertilization rate. In the P and K treatments, yields of Taro tuber were the highest at $150kg\;ha^{-1}$ fertilization. Fertilizer use efficiency was decreased by increase of N and K fertilization. Crude protein of Taro tuber was the highest at practical fertilization. Sucrose content of tuber was influenced by phosphate application.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.6
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• pp.719-723
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• 2010

Ingestion of forage containing a large quantity of soluble oxalate can result in calcium deficiency and even death of livestock. Fertilization is one of the most practical and effective ways to improve yield and nutritional quality of forage. An experiment was conducted to determine the effects of nitrogen (N) fertilization (150, 300 and 600 kg/ha) across varying levels (150, 300 and 600 kg/ha) of potassium (K) on oxalate accumulation in napiergrass (Pennisetum purpureum). Application of N at 300 kg/ha produced higher dry matter yield than at 150 or 600 kg/ha, while K fertilization had no effect on yield. In general, N fertilization did not affect the soluble and total oxalate contents, but slightly affected the insoluble oxalate content. Soluble oxalate content showed an increasing trend and insoluble oxalate content showed a decreasing trend with increasing K level, but total oxalate content remained relatively constant. There were significant interactions between N and K fertilization for the content of soluble and insoluble oxalate fractions. The greatest increase in soluble oxalate content with N level at 300 kg/ha was found at the high level (600 kg/ha) of K application. The greatest increase in insoluble oxalate content with N level at 600 kg/ha was found at the low level (150 kg/ha) of K application. These results indicated the possibility of controlling the content of soluble and insoluble oxalate fractions in forage by fertilization.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.3
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• pp.97-106
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• 2006

The pollutant concentrations at experimental paddy plots with three (excessive, standard, reduced) different fertilization rates were investigated during 2001-2002 irrigation seasons. Mean concentrations of pollutants in ponded water were not significantly different among three experimental plots, but the T-N concentrations in percolated water significantly depended on fertilization rates. The T-N, T-P and $COD_{Cr}$, concentrations in ponded water during early irrigation season (late May to mid-June) were much higher than those during later irrigation season likely due to fertilization and low uptake by young rice crops. The T-N concentrations decreased but the concentrations of T-P and $COD_{Cr}$, increased three days after tillering fertilization. The removal rates of T-N by paddy plots were $0.13-0.16g/m^2{\cdot}d$ for an excessive fertilization plot, $0.08-0.25g/m^2{\cdot}d$ for a standard fertilization plot, and $0.03-0.34g/m^2{\cdot}d$ for a reduced fertilization plot three days after tillering fertilization. On the other hand, T-P and $COD_{Cr}$, were released three days after tillering fertilization.

• Asian Journal of Turfgrass Science
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• v.5 no.2
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• pp.69-73
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• 1991

This experiment was carried out in order to study the effect of nitrogen fertilization on the growth of Colonial bentgrass and thatch accumulation under no removing clipping residues. Nitrogen fertilization was applied as 4 levels, 10, 20, 25 and 20gN/m$^2$, respectively. The results were as follows : 1.Response of plant length and dry weight of thatch to N fertilization were significant differences between N levels. It suggested that N fertilization with no clipping residues greatly affected to the growth and thatch accumulation of colonial bentgrass.2.Plant length, the dry weight of clipping residues and coverage were obtained the highest values at 20g N. It was assumed that 20gN/m$^2$ is the limiting N level to obtain the favorable growth of Colonial bentgrass. 3.The dry weight of thatch and lignin content were increased with high nitrogen fertilization level. 4.The dry weight of thatch indicated positive significant correlation with lignin content. 5. The dry weight of thatch per N(THg/N) at 20g~25g/m$^2$ levels were obtained the lowest values than of other levels of N. It may be due to the stimulating of microbial activity by adequate to N fertilizers which increased mineralization of thatch.

• KCID journal
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• v.14 no.1
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• pp.57-66
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• 2007

Temporal changes in total nitrogen (T-N) and phosphorus (T-P) concentrations in paddy floodwater in response to fertilization under rain-shielding pot and small-scaled field conditions were investigated. On the basis of the changing patterns, suggestions for the use of fertilization factors, such as days after fertilization, in developing models for the estimation of T-N and T-P loads from paddy fields were made. Total N concentration was susceptible to fertilization, showing a peak concentration right after fertilization followed by a decreasing pattern with the elapse of days after fertilization. The decreasing pattern of T-N concentration followed the first- order kinetics, indicating that the models are likely to be an exponential equation using days after fertilization as an independent variable. Comparison between the pot and field experiments conducted with soils different in soil fertility revealed that indigenous soil N concentration significantly affected T-N concentration, and this suggests that soil N status can be used as the second variable for the models. Meanwhile, temporal changes in T-P concentration did not respond to P fertilization as sensitively as T-N. In combination with other published results, our study suggests that rainfall intensity and other factors associated with farming activities that are likely to cause disturbance of soil particles containing P may be used as possible variables for the models.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.3
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• pp.274-282
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• 1992

Annual forage crops have been increasingly important for conpensating insufficient forage production of perennial pastures took place for short interval. This experiment was conducted to determine the effect of sward composition and NㆍP fertilization on forage production and intercompetition of subterranean clover-Italian ryegrass and berseem clover-Italian ryegrass. The two clovers were grown in the field at the clover/ryegrass ratios of 0/100, 25/75, 50/50, 75/25 and 100/0 where no, N (200 kg /ha), P (50 kg /ha) or NㆍP fertilization was done. Each crop was separated after harvest and drying. Relative Crowding Coefficient (RCC), aggressivity and Relative Yield Total (RYT) were analyzed on the basis of the harvested dry matter of each crop. Berseem clover-ryegrass mixtures produced greater yield than subclover-ryegrass mixtures as a result of higher yields of the two component species. In the former forage yield was increased with increased rate of clover up to 75%, while in the latter the highest yields were obtained at more than 50% of the clover. In the mixtures N stimulated the growth of ryegrass, whereas P did only that of subclover. The two clovers produced more forage than the companion grass under no and only P fertilization although the reverse result was true under N or NㆍP fertilization, but the annual forage yield was decreased in the order of N and P, N, P, and no fertilization. The mixture yields were overyielded compared to the Expected Yield. Although generally RCCs and RYTs of subclover were higher than those of berseem clover in the mixtures differing the composition rate or under no and only P fertilization, those of the former clover were lower under N or NㆍP fertilization. In the clover-ryegrass mixtures, ryegrass acted as an aggressor and became more aggressive under P fertilization.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.105-110
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• 2013

This study was carried out to investigate the effect of nitrogen (N) fertilization on the forage growth, production and quality of native reed (Phragmites communis) grasses. Field experiments were conducted in Cheonan and in Ansan, 2012. Treatments were control (no N fertilization), 50 kg/ha and 100 kg/ha in Cheonan plots (fertilization on April $30^{th}$, and harvest on June $21^{st}$). Treatments in Ansan plots were control (no N fertilization) and 60 kg/ha (fertilization on May first, and harvest on August first). Forage growth and leaf colors were improved in N fertilized plots. However, the drymatter (DM) percentage was slightly decreased with N fertilization. Forage yields, in terms of DM, crude protein (CP) and digestible DM (DDM), were significantly increased with N fertilization in both sites. In Cheonan, DM, CP and DDM yields per ha were 4,026 kg, 235 kg and 1,850 kg, respectively, in the control plot, and were 4,658 kg, 306 kg and 2,388 kg, respectively, in the N 50 kg plot, and 5,622 kg, 446 kg and 3,143 kg, respectively, in the N 100 kg plot. In Ansan, DM, CP and DDM yields per ha were 2,802 kg, 177 kg and 1,288 kg, respectively, in the control plot, and were 3,876 kg, 294 kg and 1,853 kg, respectively, in the N 60 kg plot. Forage quality in terms of CP content, in vitro DM digestibility (IVDMD) and relative feed value (RFV) were also increased with N fertilization in both sites. In Cheonan, the CP content, IVDMD and RFV were 5.85%, 45.96% and 64.5 (grade 5), respectively, in the control plot, 6.58%, 51.27% and 72.3 (grade 5), respectively, in the N 50 kg plot, and 7.94%, 55.91% and 72.7 (grade 5), respectively, in the N 100 kg plot. In Ansan, the CP content, IVDMD and RFV were 6.30%, 45.98% and 70.2 (grade 5), respectively, in the control plot, and 7.59%, 47.80% and 78.3 (grade 4), respectively, in the N 60 kg plot. In conclusion, N fertilization of 60~100 kg/ha was desirable for greater forage production, with a higher quality of native Phragmites communis achievable. This should only be applied if the fertilization area is not located at a riverside/streamside or in riparian land where there is a high risk of water pollution by fertilization.