• Journal of Plant Biology
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• v.19 no.2
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• pp.37-40
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• 1976

The experiment designed to obtain information relative to the favourable levels to apply N.P.K fertilizer was conducted at the hop garden of College of Agriculture, S.N.U. in 1975. The varieties used were 1-year-old Cascade, Hallertau and Shinshuwase. The design of the experiment was a split plot design with 3 replications. Yields were recorded as fresh weight of harvested cones in gram per split plot. The results obtained from the experiment were as follows: 1. The results from analysis of the data for 3 varieties indicated that significant increase in yield were found due to the application of 46g N, 20g P2O5 and 60kg K2O per plant, although higher level thn the above caused a remarkable reduction of yield. 2. The individual fresh weight of harvested cones was significantly increased with application of nitrogen, phosphorus and potash, regardless of fertilizer levels. 3. Analysis of variance for yields showed that there were no significant interaction between fertilizer level and variety, i.e., all varieties used might require the same fertilizer level.

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.2
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• pp.115-122
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• 2000

This study was carried out to determine a fertilization rate for productivity and nutritive value improvement of silage corn, using two kinds of composts, and to examine the potential possibility of utilization as an organic fertilizer. The experiment was conducted on the field plot at Gongiam, Kwangju, Kyunggi-Do for 3 years, from 1996 to 1998, and arranged in split-plot design with three replications. The main plots were two kinds of composts such as swine manure fermented with sawdust (SMFWS) and swine manure fermented without sawdust (SMF). Subplots were the nitrogen fertilization rates (0, 100, 200, 300 and 400kgN/ha/year). The dry matter (DM) yield increased as the nitrogen fertilization rate increased up to a rate of 300 kg N/ha, but decreased at rate of 400 kg N/ha. Dry matter yield in SMFWS treatment was higher than that of SMF treatment, but there was no significant difference between SMFWS and SMF treatments. Net energy for lactation (NEI) and total digestible nutrients (TDN) in corn increased as the fertilization rate of SMFWS and SMF increased, and crude protein (CP) content increased by the fertilization of SMFWS and SMF. No difference of CP, NEI and TDN was found between SMFWS and SMF treatments.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.102-108
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• 2006

It is very important to improve fertilizer use efficiency for the saving of fertilizers and for environmental purposes as well. However, there was no effective ways for the fertilization in the mid of growth under the plastic film mulching cultivation so far. For this, a Band Spotty Fertilization (BSF) machine was developed recently. So, we tried to establish a low input fertilization technique using this BSF machine in the vinyl mulching cultivation of onion (Allium cepa L.). Fertilization efficiency, soil properties, and crop yield were examined and compared among treatments from 2000 to 2001. The content of exchangeable K in soils were higher after fertilization but that of available $P_2O_5$ was lower than before the experiment in all plots. The content of nitrate-N was highest at the early growth stage, and higher in BSF plots than that of conventional fertilization (CF). BSF plot showed higher growth rate, and uptake amount of nitrogen of onion by 59-69% than that of CF. N use efficiency in BSF was higher in the order of two time-split application, one time-split application, and three time application. K use efficiency was high 13-17% BSF plots than that in CF($63kg\;ha^{-1}$) plots. The amount of residual N in soils was high by 8-14% in BSF plots compared to that in CF plots, and the loss of N was lowered 26-34% by BSF. Also, the amount of residual K in soils was high by 13-18% and the loss of K was low by 29-31% in BSF plots compared to that in CF plots. The yield of onions increased by 7-13% by BSF due to increased diameter and weight of bulbs. As the results, N fertilization efficiency increased by 22-42% by BSF.

• Applied Biological Chemistry
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• v.25 no.3
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• pp.150-154
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• 1982

Top-dressing pot experiment with $^{15}N$ urea was carried out by using three varieties. Two-split application was much better for Tongil line than 4-split. Fertilization efficiency (Fe), use efficiency (Eu) and absorbed fertilizer nitrogen efficiency (Ef) were much greater in 2-split than in 4-split. The order of Fe followed that of Ef. Grain yield and $^{15}N$ excess % among plant parts suggest that Tonsil line uptakes fertilizer nitrogen much in early stage and retranslocated well later. The order of soil nitrogen increment in plant per fertilizer nitrogen in plant $({\Delta}Ns/Nf)$ might be an index of soil nitrogen use efficiency due to fertilizer.

• Clinical and Experimental Reproductive Medicine
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• v.42 no.2
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• pp.45-50
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• 2015

Objective: Artificial oocyte activation (AOA) is an effective method to avoid total fertilization failure in human in vitro fertilization-embryo transfer (IVF-ET) cycles. AOA performed using a calcium ionophore can induce calcium oscillation in oocytes and initiate the fertilization process. We evaluated the usefulness of AOA with a calcium ionophore in cases of total fertilization failure in previous cycles and in cases of severe male factor infertility patients with non-motile spermatozoa after pentoxifylline (PF) treatment. Methods: The present study describes 29 intracytoplasmic sperm injection (ICSI)-AOA cycles involving male factor infertility at Cheil General Hospital from January 2006 to June 2013. Patients were divided into two groups (control, n=480; AOA, n=29) depending on whether or not AOA using a calcium ionophore (A23187) was performed after testicular sperm extraction-ICSI (TESE-ICSI). The AOA group was further split into subgroups according to sperm motility after PF treatment: i.e., motile sperm-injected (n=12) and non-motile sperm-injected (n=17) groups (total n=29 cycles). Results: The good embryo rate (52.3% vs. 66.9%), pregnancy rate (20.7% vs. 52.1%), and delivery rate (10.3% vs. 40.8%) were lower in the PF/AOA group than in the control group. When evaluating the effects of restoration of sperm motility after PF treatment on clinical outcomes there was no difference in fertilization rate (66.6% vs. 64.7% in non-motile and motile sperm, respectively), pregnancy rate (17.6% vs. 33.3%), or delivery rate (5.9% vs. 16.7%) between the two groups. Conclusion: We suggest that oocyte activation is a useful method to ensure fertilization in TESE-ICSI cycles regardless of restoration of sperm motility after PF treatment. AOA may be useful in selected patients who have a low fertilization rate or total fertilization failure.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.3
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• pp.215-222
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• 2016

Nitrogen (N) fertilizer management is one of the important aspects of economic production of sorghums in sustainable agriculture. The aim of the study was to evaluate the effects of different N application rates and its split N application methods on productivity, growth characteristics, N accumulation, N use efficiency (NUE), and feed value of Sorghum ${\times}$ Sudangrass hybrids. Treatments consisted of five N application rates (0, 150, 200, 250, and $300kg\;ha^{-1}$) and two split N application methods (40% in basal N, 30% at the growing stage, and 30% after the first harvest vs. 50% in basal N and 50% after the first harvest). Plant height, leaf width, and stem diameter were increased ($p{\leq}0.05$) with increasing N fertility rates at each harvest. Chlorophyll content (expressed as SPAD values) was the highest at a rate of $300\;kg\;N\;ha^{-1)$ (first harvest, 46.32; second harvest, 33.09). It was the lowest at zero N (first harvest, 21.56; second harvest, 18.5). Total N, N uptake, and NUE were increased with higher N rates. Split N application had little effect on total N, amount of N uptake, or NUE. Total dry matter yields were the highest ($21,715\;kg\;ha^{-1}$) at a rate of $300\;kg\;N\;ha^{-1}$. It was the lowest ($10,054\;kg\;ha^{-1}$) at zero N. Our results suggest that more than $300\;kg\;N\;ha^{-1}$ can improve dry matter yield to be above 116% compared to zero N, thus enhancing the agronomic characters of sorghums. However, no significant effect had been found for split N application. Further work is needed to determine the optimal N levels and the effect of split N application rates.

• Weed & Turfgrass Science
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• v.7 no.1
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• pp.76-86
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• 2018

Turfgrass species were evaluated for their rooting and foliar characteristics, and their interaction with the soil. The rooting system was divided into three compartments, one above another, such that the top and bottom compartments of the root system could be supplied with a nutrient deprived solution. Exposure of parts of the roots to nitrate deprivation caused a localised retardation of root initiation and extension, compared with zones receiving the full supply of nutrients. This resulted in considerable modification to root form, coupled with a significant depression in foliar growth. The extension of roots was the least affected by the deprivation of potassium. Phosphate and calcium deprivations gave rise to similar responses in root and foliar formation. Results from this study showed that external concentrations of nitrogen, phosphorus, potassium and calcium are required by the root system in varying amounts for optimal growth of roots. Turfgrass coverage and turf quality ratings further reinforced these findings. No significant difference was observed between the different grasses examined here. All three species responded similarly to the deprivation of the various nutrients. Results from this study confirmed that targeted fertilization programs are beneficial and can help reduce cost, chemical usage and prevent leachate and contamination.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.2
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• pp.124-130
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• 1986

To find out the optimum split application ratios of fertilizer nitrogen and potassium in the newly opened pasture at spring, a field experiment was conducted. Two levels of nitrogen and potassium application and three split application ratios of both fertilizer were treated by split design with 4 replications. The experiment was carried out from March, 1984 to October, 1985 on the experimental field of the Livestock Experiment Station in Suweon. The results obtained are summarized as follow: 1. Total DM yield was not showed signigicant difference among split application ratios of nitrogen and potassium. 2. DM yield of grasses was 4,854 kg/ha in heavy basal application of N and $K_2$O (160 kgN: 140 kg $K_2$O/ha), it was significantly increased by 16% than of conventional dressing (80 kg N: 70 kg $K_2$O/ha). But there was almost no difference in dry matter among N and $K_2$O split application ratios. 3. Dry matter yield of legume in heavy basal dressing was decreased by 23% than that of conventional dressing. In the methods of NK application, dry matter yield of legume was tended to decrease by 3% with equal application and 9% with heavy dressing in autumn, when compared with that of heavy dressing in spring. 4. There was no significant difference in dry matter yield of native species between different basic fertilization levels, but dry matter yield of native species was decreased by 6% with equal application and more increased by 11% with heavy dressing in autumn, when compared with the yield of heavy dressing in spring. 5. In aspect of the botanical composition, the percentage distribution of grasses was increased and the ratio of legume was greatly decreased by heavy dressing at basal fertilization. Also for good maintenance of botanical composition, it is suggested that the equal split application of N and $K_2$O was desirable.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1004-1008
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• 2012

The importance of environment-friendly agriculture is being magnified as a new growth engine industry in pursuit of low carbon, green growth policies. Since 2010, the Korean government has been promoting the supply of customized fertilizers which were manufactured based on chemical properties of agricultural soils. This aims focused to improve the efficiency of fertilizer used and to protect the agricultural environment. In order to provide technical supports for pushing ahead with the environment-friendly agriculture policies, we have estimated the effects of customized fertilization (CF) on growth and yield of rice and fertilizer reduction compared to conventional fertilization (farm practice fertilization) and single-element fertilization. In rice plant growth and rice yield, no statistically significant difference between the three fertilization treatments was observed. The fertilizer reduction rate with CF compared to conventional fertilization of investigated farms was on average 17%, which covered 6% through 33%. With split ratio, CF 70 reduced the amounts of fertilizer ingredient by 5% compare to CF 50. This paper shows that the customized fertilizer application reduced the amounts of fertilizer used in rice cultivation without decrease of yields.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.350-358
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• 1998

To determine the optimum application of fertilizers for the cultivation of tomato in plastic film house, eighteen soils which contained different salt contents were taken from four different areas under plastic film house cultivation, Youngdong, Boeun, Cheongweon county, and Cheongju city. The dry weight and the amount of N, P, and K uptakes of tomato in the plot with no fertilization were considered as the factors representing the fertility of the soil. The differences in the dry weight and in the amounts of N, P, and K uptakes of plants between the plots with fertilization and with no fertilization were considered as the factors representing the total effect of fertilizer and the effects of fertilizer N, P, and K, respectively. These factors of soil fertility and fertilizer effects were estimated by correlation and regression with the chemical properties of the soil in order to find the critical levels and recommended method for optimum fertilization of tomato. The standardized partial regression coefficients of inorganic nitrogen ($NO_3-N+NH_4-N$) contents in soil for the factors of fertility ranged from 247 to 1,159, showing the best, while those of the others ranged from 0.02 to 4.02. Those of inorganic nitrogen ($NO_3-N+NH_4-N$) contents in soil for the electrical conductivity were also the best and were ranged from 35.2 to 36.0 compared with the values of less than 1.0 of the others. These results demonstrate that the content of inorganic nitrogen in the soil is the best index for both soil fertility and electrical conductivity of the soil. The critical level of inorganic nitrogen ($NO_3-N+NH_4-N$) in the soil for maximum productivity with zero value of fertilizer effects for tomato, estimated through Cate-Nelson split method was $220mg\;kg^{-1}$. This was the same value as evaluation for the cultivation of chinese cabbage. In conclusion, for optimal application of fertilizer in plastic film house, 1) no fertilization is recommended when the contents of inorganic nitrogen in the soil is more than $220mg\;kg^{-1}$; however, 2) in the case of less than $220mg\;kg^{-1}$ of inorganic nitrogen content in the soil, the optimal level of fertilization could be estimated through the regression equation between fertilizer effects and content of inorganic nitrogen in the soil.