• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.344-355
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• 2003

Water quality model applicable paddy field was developed using field experiment during 1999 ${\sim}$ 2002. This model involves inputs from fertilization and sediment release as dirac delta function and continuous source function, respectively, and can simulate various processes such as ponded depth, surface drainage, total nitrogen concentration and total phosphorus concentration in a daily basis. The model was calibrated using data collected from field experiments which was irrigated with ground water and validated from field experiments which was irrigated with surface water. The nutrient concentration of surface water depended on the fertilization and dirac delta function can efficiently explain the valiance of nutrient concentration of surface water by fertilizer. As a result of calibration and validation, this model demonstrates good agreement. The model fit efficiencies ($R^2$) of ponded depth, surface concentration of TN and TP were 0.93,0.98 and 0.95, respectively for calibration, and those of TN and TP were 0.99 and 0.70, respectively for validation. We can apply lake and reservoir model to analysis paddy field considered with shallow ponded system, but it will need so many parameters and have much uncertainty. Fortunately, paddy field have a series of cultural practices yearly basis, such as irrigation-fertilization-forced drain-harvest with a similar time , so simple model may explain the mechanism for paddy field. Water quality model for paddy field developed in this study is simply, needs little parameters, but appeared high applicability to evaluate paddy filed drainage. We recommend this model to estimate nutrient loading from paddy field and establish best management practice.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.1
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• pp.24-30
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• 1986

This experiment was carried out in order to study the effect of fertilizer application and seasonal changes on the productivity of the native reed (Phragmites communis Trinius) on the reclaimed tidal flate in Chonnam province. The samples of reed were taken at about 30-days interval from May to October, 1982 and evaluated plant height, blade & sheath-stem ratio, grass yield, the feed compositions and in vitro dry matter digestibility (IVD). The results are summarized as follows: 1. Plant height, grass yield, crude protein content and in vitro dry matter digestibility of the reed were significantly increased by fertilizer application, and ADF content was significantly decreased. 2. According to the significance test of coefficience, there was a significant negative correlation (P<0.05) between in vitro dry matter digestibility and plant height, grass yield, and the content of crude fiber and ADF, but a positive correlation (P<0.05) between in vitro dry matter digestibility and blade & sheath-stem ratio, and the content of crude protein and crude fat.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.314-320
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• 1984

Effects of phosphorous fertilizer on the growth habit and yield of monoculm and branch types of two leading sesame varieties was investigated. The photosynthetic rate of at each growing stage was high at the flowering stage. The photosynthetic rate of monoculm sesame variety, Pungnyeon was high prior to flowering stage, while the Kwangsan variety, branch type was high after the flowering stage. The level of phosphate were most effective in increasing photosynthesis when standard level of fertilizer was applied in both varieties. Kwangsan variety showed higher photosynthetic rate per unit area, higher NAR, and CGR and higher LAR and RGR at the maximum flowering stage than the Pungnyoeon variety. Those characters attained maximum level when standard levels of phosphorous fertilizer were applied. The protein and oil content of seeds were higher in Kwangsan variety compared with Pungnyeon. However, the carbohydrate of seeds was high for Pungnyeon variety. The highest protein content was attained when standard level of fertilizer were applied. The oil content appeared to increase as the level of applied fertilizer increased. The results suggest that the vegetative growth and seed yields of sesame may be enough with present level of fertilizers. However, higher amount of phosphorous fertilizer may be required to increase the oil content of sesame seeds.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.349-355
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• 2008

The causes of salt accumulation in soils of plastic film houses nearby Sumjin river estuary in Mokdo-ri($127^{\circ}46'E\;35^{\circ}1'N$), Hadong, Gyeongnam, Korea were investigated in 2006. With chemical properties soils and water analyzed and fertilization status monitored, the study showed that mean salt concentration of soil was much higher at EC $4.3\;dS\;m^{-1}$ than the Korean average (EC $2.9\;dS\;m^{-1}$) in 2000s for plastic film house's soil with exchangeable Na $0.8\;cmol^+\;kg^{-1}$ and water-soluble Cl $232\;mg\;kg^{-1}$, and then might result to salt damage in sensitive crop plants. Salt concentration of ground water used as main irrigation water source contained very high EC with corresponding value of $2.6\;dS\;m^{-1}$. Particularly, increase of EC value was directly proportional with the increased pumping of ground water used as a water-covering system in order to protect the temperature inside plastic film houses from the early winter season. High Na and Cl portion of ions in water might had contributed to the specific ion damage in the crops. Secondly, heavy inputs of chemicals and composts significantly increased the accumulated salts in soil. Conclusively, salt accumulation might had been accelerated by use of salted-groundwater irrigation and heavy fertilization rate. To minimize this problem, ensuring good quality of irrigation water is essential as well as reducing fertilization level.

• Korean journal of applied entomology
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• v.9 no.1
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• pp.7-13
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• 1970

1. Kum Nam Poong which is highly susceptible to bacterial leaf blight was used as the host plant throughout this experiment. Xanthomonas oryzae 6526 was inoculated on the top of upper leaves by single needle inoculation method. After 14 days, the enlarged spots were examined in the experimental pots. Each of 3 levels of nitrogen, phosphate and potassium pots were arranged at random with three replications. 2. The amounts of nitrogen fertilizer applied and the lesion development of bacterial leaf blight were positively correlated regardless of application of phosphate and potassium fertilizers. 3. The effect of phosphate fertilizer on the lesion development was not significantly different from standard level. The lesion development was stimulated when the amount of phosphate fertilizer was increased as twice as standard level. 4. The inhibitory effect of potassium fertilizer on leaf blight was maximum by applying standard level. The stimulative effect of potassium fertilizer on the lesion development, however, was noticed. when potassium fertilizer applied was increased as twice as the standard level. 5. The heading date and spike number of rice plant were significantly correlated with the lesion development, and such phenomena were depended on the amount of nitrogen fertilizer applied regardless of the other fertilizers applied in this experiment.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.390-396
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• 2015

Water shortage is becoming a serious problem of turfgrass management on sand green. Many superintendents in golf course in Korea have interested in use of irrigation of recycled water for turfgrass water management. This study was conducted to investigate the effect of greywater as an irrigation source on the growth and quality of creeping bentgrass green. Turfgrass was irrigated with tap water (TW) and greywater (GW), under with or without compound fertilizer application (nonfertilizer + TW, N-TW; non-fertilizer + GW, N-GW; fertilizer + TW, F-TW; fertilizer + GW, F-GW). The chemical properties of the green sand soil were not changed by irrigation. Turf color index, chlorophyll index, root length, clipping yield and nutrient uptake of GW treatment were similar to TW treatment. The growth and quality of turfgrass were more likely related with the fertilizer application than irrigation source or quality. These results indicated that GW could be used as alternative irrigation source on the sand greens of golf courses.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.2
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• pp.123-128
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• 1998

Legume winter cover crop hairy vetch(Vicia villosa Roth, HV) can supply mineral nitrogen for silage corn by HV cover killed. The purphose of this study was to understand changes of soil mineral N, yield and N uptake of silage corn by N level (0, 135kgFN/ha) and cover cmp(no cover crop: NCC, hairy vetch cover crop: HVC) at field of Crop Experiment Station in 1996. HV growth decreased soil mineral N concentration before seeding corn, but killed HV cover increased concentration of soil mineral N at surface soil (0~7.5cm) at six-leaf stage of corn. Total dry matter(DM) and N uptake of corn averaged over N level was more decreased in HVC than in NCC at silk stage, but N uptake of corn after silk was more increased in HVC than in NCC by N mineralized fiom HV killed, especially in OkgFNJha. N fertilization increased total DM and and N uptake of corn averaged over cover crop, especially more increased the DM and N uptake before silk stage. Early application of N fertilizer was recommendable in netillage silage corn using hairy vetch cover crop.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.460-464
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• 2007

This study was carried out to elucidate the proper split application method of nitrogen fertilizer for early dry seeding culture of rice in Honam plain area from 1997 to 1998 in Korea. Dongjinbyeo was selected as rice variety for this experiment. The rate of $160kg\;ha^{-1}$ of nitrogen was split as 40-30-30% of total nitrogen at three different application time combination ; T1) basal-5th leaf-panicle formation(PF) stage, T2) 3rd leaf-5th leaf-PF, and T3) 3rd leaf-7th leaf-PF. The content of $NH_4-N$ in soil at 5th leaf stage was higher in top dressing plots(T2, T3) compared with basal application(T1), at 7th leaf stage it was most in top dressed at 3rd leaf and 5th leaf stage, but there was no difference at heading stage. Amount of nitrogen uptake and nitrogen use efficiency was higher in the order of T3, T2 and T1(basal application). Spikelet number per unit area was more in the order of T3, T2 and T1, but rate of ripened grain and 1,000 grain weight were not significantly different among three nitrogen split application methods. Milled rice yields were higher in top dressed plots compared with basal nitrogen application plots. From the results of this experiment, reasonable nitrogen split application method for early dry seeding culture of rice could be 40-30-30% of total nitrogen at 3rd leaf, 7th leaf and panicle formation stage.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.331-337
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• 2023

Physiological disorders in pear fruit are mainly caused by problems during the growing season, such as lack of calcium in the soil, poor drainage, low porosity, vigorous pruning, and excessive fruiting. In this study, soil physicochemical properties and leaf characteristics were analyzed in pear orchards in four regions of Korea where chlorosis symptoms occurred to determine the causes of chlorosis. The color of chlorotic leaves was diagnosed using the naked eye or SPAD and Hunter values. The soil of the chlorotic orchard had a significantly higher soil pH than that of the regular orchard. Although adequate soil depth was not significantly associated with chlorosis, combined with over-fertilization of the soil with lime, it could potentially impair plant iron uptake. Chlorotic leaves had significantly lower iron and calcium contents and significantly higher magnesium contents than those of regular leaves. Therefore, the intensive occurrence of chlorosis during secondary shoot development around June and July when it is hot and humid may be due to impaired iron and calcium absorption, leading to physiological disorders. To solve this problem, avoiding the over-application of lime and applying foliar fertilizers containing chelated iron is recommended.

• Korean Journal of Medicinal Crop Science
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• v.4 no.3
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• pp.265-268
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• 1996

According to the research of the cultivation result of Gardenia for 5 years to investigate its cultivation conditions and problems, the development of the variety with early mature and high yielding is urgent and that of rooted cutting cultivation method by the experiment of rooted cutting, bed soil, growth regulator and cutting period are pressing. The development of cultivation method with planting year, planting density, supplementary period and amounts of supplementary of Gardenia planted on growing field are required and for the disease and insect pest control, the research of the cultivation method with disease and insect pest resistance is ne­eded by auxotrophic fertilizing and organic agricultural method, not by agriltural chemicals.