• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.309-313
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• 1997

Field experiments were conducted on Jeonbug series (Fine silty, mesic family of Aeric Fluventic Haplaquepts), to study the effect of split application of N fertilizer in combination with rice straw on N use efficiency of dry-soil-direct seeded paddy rice. Treatments involved conventional application of N (in three splits; 40% at planting, 30% at five leaf stage and at heading stage) without rice straw, all basal application of N with straw application (5000 kg/ha), N application in two splits (70% at planting and 30% at heading stage) with rice straw application and N application in three splits (40% at planting, 30% at five leaf stage, 30% at heading stage) with application of rice straw. There was Zero N plot too for the estimation of N use efficiency. Seeding was done on dry soil and the filed was flooded 32 days after seeding. The fertilizer application rates were 160, 70, and 80 kg/ha of N, $P_2O_5$ and $K_2O$, respectively. The experiment was conducted for two years, in the same filed. The apparent use efficiency of fertilizer N by rice tended to be higher under the application of rice straw when N was applied in three splits. This, however, did not increase the yield of rice significantly. Even under the application of rice straw, the apparent N use efficiency was lower when N fertilizer was applied in one dose at the planting and in two splits. The lower N use efficiency in these cases, did not yield of rice significantly. The periodical analysis of mineral N in the soil suggested that higher mineral N in the soil at the early stages was responsible for the lower apparent N use efficiency.

• Journal of Crop Science and Biotechnology
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• v.10 no.2
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• pp.57-63
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• 2007

Due to the strong influence of nitrogen(N) on plant productivity, a vast amount of N fertilizers is used to maximize crop yield. Over-use of N fertilizers leads to severe pollution of the environment, especially the aquatic ecosystem, as well as reducing farmer's income. Growing of N-efficient cultivars is an important prerequisite for integrated nutrient management strategies in both low- and high-input agriculture. Taking maize as a sample crop, this paper reviews the response of plants to low N stress, the physiological processes which may control N-use efficiency in low-N input conditions, and the genetic and molecular biological aspects of N-use efficiency. Since the harvest index(HI) of modern cultivars is quite high, further improvement of these cultivars to adapt to low N soils should aim to increase their capacity to accumulate N at low N levels. To achieve this goal, establishment and maintenance of a large root system during the growth period may be essential. To reduce the cost of N and carbon for root growth, a strong response of lateral root growth to nitrate-rich patches may be desired. Furthermore, a large proportion of N accumulated in roots at early growth stages should be remobilized for grain growth in the late filling stage to increase N-utilization efficiency. Some QTLs and genes related to maize yield as well as root traits have been identified. However, their significance in improving maize NUE at low N inputs in the field need to be elucidated.

• Asian Journal of Turfgrass Science
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• v.6 no.1
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• pp.23-28
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• 1992

Urea, the major N source of world agriculture involves a serious urea-N loss through NH$_3$volatilization. Approaches to decrease N loss include using urease inhibitors in view of the environmental protection and the increase of urea-N efficiency. The purpose of laboratory researches was toassess the potential value of urease inhibitors to increase urea-N efficiency in soil and Kentucky blue-grass(Poa Pratensis L.) turf. The activity of urease inhibitors Phenyiphosphorodiamjdate(ppD) and N-(n-butyl) thiophosphoric triamjde(NBPT) measured to break-down ammonia volatilization. The soil and turf used in this project were from the fairway in one of the Korean gof course. The researches were carried out for two weeks to measure the urease activities on urea hydrolysis under four temperatures (10~ 40$^{\circ}C$) and for one week on turfgrass using forced-draft system. Results indicated that Urea-N involves considerable loss through gaseous NH$_3$ by urease activities in plant-soil systems. Urease inhibitors PPD and NBPT have potential value for increasing N use efficiency by reduing NH$_3$ volatilization. NBPT deserves futher evaluation as fertilizer amendment than PPD use of urea in turf industries.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1096-1103
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• 1999

A study was conducted to clarify the impact of recombinant porcine somatotropin (pST) on the efficiency of absorbed nitrogen use for protein deposition in growing pigs. Three levels of dietary crude protein (9.0, 11.5, 14.0% CP) were used. Each had either a sub-optimum or near optimum lysine: CP concentration (Low-lysine, 3.8 g/100 g CP and High-lysine, 5.5 g/100g CP) in order to achieve different metabolic efficiencies for nitrogen deposition (ca. 45 vs. 60%). Twelve crossbred female pigs $(59{\pm}4kg\;BW)$ were placed in metabolism cages and fitted with bladder catheters. Each pig received an excipient injection daily for the first 10-d, a pST (5 mg/d) injection for the second 10-d, and then excipient for the last 10-d. Pigs were randomly assigned to one of six dietary treatments (2 pigs/diet) and fed 4 times per d at $92g/kg\;BW^{0.75}$ $(3{\times}maintenance)$. Means for the excipient period were compared to means for the pST period. Urinary nitrogen (N) output declined in pST-treated pigs (p<0.01) irrespective of dietary protein content or lysine level. Nitrogen retention increased by an average of 11% (p<0.01) with pST treatment (726 vs. $803mg\;N/kg^{0.75}\;BW/d$). Forty-eight percent of the absorbed N was retained with Low-lysine diets, but this increased to 53% with pST injection (+11%, p<0.01). Pigs fed High-lysine diets retained 62% of absorbed N which increased to 69% with pST (+11% p<0.01). the addition of lysine improved N use by 27% (High vs. Low, p<0.01), but the effect of lysine and pST was additive (+40%). Therefore, pST improves N retention and the efficiency of apparently absorbed N use in growing pigs (>60kg). It does so with diets having the potential for either low or high efficiencies of N use (48% and 62%). More work is needed to determine if the partial efficiency of N use improves in direct proportion to pST dose since the improvement in protein deposition is a function of pST dose.

• 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.

• Molecules and Cells
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• v.23 no.1
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• pp.72-79
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• 2007

Demand for low-input sustainable crop cultivation is increasing to meet the need for environment-friendly agriculture. Consequently, developing genotypes with high nutrient use efficiency is one of the major objectives of crop breeding programs. This study was conducted to identify QTLs for traits associated with physiological nitrogen use efficiency (PNUE). A recombinant inbred population (DT-RILs) between Dasanbyeo (a tongil type rice, derived from an indica ${\times}$ japonica cross and similar to indica in its genetic make-up) and TR22183 (a Chinese japonica variety) consisting of 166 $F_8$ lines was developed and used for mapping. A frame map of 1,409 cM containing 113 SSR and 103 STS markers with an average interval of 6.5 cM between adjacent marker loci was constructed using the DT-RILs. The RILs were cultivated in ordinary-N ($N-P_2O_5-K_2O=100-80-80kg/ha$) and low-N ($N-P_2O_5-K_2O=50-80-80kg/ha$) (100 kg/ha) conditions. PNUE was positively correlated with the harvest index and grain yield in both conditions. Twenty single QTLs (S-QTLs) and 58 pairs of epistatic loci (E-QTLs) were identified for the nitrogen concentration of grain, nitrogen concentration of straw, nitrogen content of shoot, harvest index, grain yield, straw yield and PNUE in both conditions. The phenotypic variance explained by these S-QTLs and E-QTLs ranged from 11.1 to 44.3% and from 16.0% to 63.6%, respectively. The total phenotypic variance explained by all the QTLs for each trait ranged from 35.8% to 71.3%, showing that the expression of PNUE and related characters depends signify- cantly upon genetic factors. Both S-QTLs and E-QTLs may be useful for marker-assisted selection (MAS) to develop higher PNUE genotypes.

• Environmental Engineering Research
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• v.13 no.4
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• pp.171-176
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• 2008

Studies on visible-light-driven photocatalysis of air pollutants at indoor air quality (IAQ) levels have been limited. Current study investigated visible-light derived photocatalysis with N-doped and S-doped titanium dioxide ($TiO_2$) for the control of benzene at indoor levels. Two preparation processes were employed for each of the two types of photocatalyst: urea-Degussa P-25 $TiO_2$ and titania-colloid methods for the N-doped $TiO_2$; and titanium isopropoxid- and tetraisopropoxide-thiourea methods for the S-doped $TiO_2$. Furthermore, two coating methods (EDTA- and acetylacetone-dissolving methods) were tested for both the N-doped and S-doped $TiO_2$. The two coating methods exhibited different photocatalytic degradation efficiency for the N-doped photocatalysts, whereas they did not exhibit any difference for the S-doped photocatalysts. In addition, the two doping processes showed different photocatalytic degradation efficiency for both the S-doped and N-doped photocatalysts. For both the N-doped and S-doped $TiO_2$, the photocatalytic oxidation (PCO) efficiency increased as the hydraulic diameter (HD) decreased. The degradation efficiency determined via a PCO system with visible-light induced $TiO_2$ was lower than that with UV-light induced unmodified $TiO_2$, which was obtained from previous studies. Nevertheless, it is noteworthy that for the photocatalytic annular reactor with the HD of 0.5 cm, PCO efficiency increased up to 52% for the N-doped $TiO_2$ and 60% for the S-doped $TiO_2$. Consequently, when combined with the advantage of visible light use over UV light use, it is suggested that with appropriate HD conditions, the visible-light-assisted photocatalytic systems can also become an important tool for improving IAQ.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.11a
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• pp.135-136
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• 2000

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.842-847
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• 2005

In recent railroad markets, the use of steel sleepers is gradually increased due to various advantages in resistance for impact as well as economical efficiency for production, construction. maintenance and recycle. The typical steel sleepers which are successfully used in railroad markets are n-type of Corus Inc. in England and Y-type of ThyssenKrupp Gft Gleistechnik in Germany. Both types have merits and demerits in safety and economical efficiency. In 1990, n-type steel sleeper was developed in Korea, but was failed in putting into practical use, due to the subsidence into the ballast by Jive loads and welding crack, etc.. In this paper, in order to develop optimal shape of n-type steel sleepers for domestic rail mads, parametric studies for cross section, thickness, are performed.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.138-143
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• 2011

BACKGROUND: This study was conducted to investigate growth and yield of organically grown rice under a typhoon during a fall. The treatments included NPK chemical fertilizer, compost, oilcake, oilcake 2X, hairyvetch, and vetch+rye. METHODS AND RESULTS: Nutrient applications were made at rates equivalent to approximately 0.9 kg of actual N per acre. Oilcake and hairyvetch treatments had the lowest C:N ratio, but compost had the highest C:N ratio of 34:1. Rice treated by organic nutrient sources had great growth and development at the beginning of the growing season but had depressed growth and yield at the harvest. Oilcake 2X-treated rice in early growing season, especially, showed better growth and development than rice treated by other nutrient sources but was severely lodged at the harvest season due to the typhoon. Compost treatment with high C:N ratio slowly released inorganic N and produced poor rice growth and yield; however, it recued rice lodging. N uptake was the greatest for the oilcake 2X and vetch+rye treatments but the lowest for the compost, which was the similar pattern to the N use efficiency; the greatest and lowest N use efficiency was observed for the oilcake 2X (55%) and compost (5%), respectively. CONCLUSION(s): Rice lodging should be prevented by reducing the excessive nitrogen supplement, resulting from the lower C:N ratio of the organic materials as well as prevented by the radical midsummer drainage. Vetch+rye treatment with 25:1 of C:N had optimum vegetative growth and reduced rice lodging, which increased N use efficiency and yield.