• 한국농공학회논문집
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• 제55권2호
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• pp.21-27
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• 2013

The present study explored the way to desalinate seawater for agricultural irrigation using forward osmosis (FO) process using liquid fertilizer as draw solution. FO experiments were performed in a cross flow mode using flat sheet FO membrane. The effect of membrane orientation, flow rate, and draw solution concentration on the performance of forward osmosis was investigated by measuring water flux of forward osmosis membrane. The water flux when the draw solution was placed against the membrane active layer was lower than the water flux when the feed solution was placed against the membrane active layer. This results indicated that the decrease of effective osmotic pressure by dilutive internal concentration polarization was less than that by concentrative internal concentration polarization. Increasing flow rate from 66.7 to 133.1 $cm^3$/min resulted in increase of the water flux when the membrane active layer orient to draw solution and feed solution, respectively. The reduction of resistance to water flow increased water flux at higher flow rate. The water flux of FO membrane increased with increasing draw solution concentration from 10000 to 30000 mg/L. The water flux for $KH_2PO_4$ draw solution was similar to that for commercial fertilizer. Optimization of FO process would contribute to economically desalinate brackish water for agricultural use.

• 한국토양비료학회지
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• 제44권1호
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• pp.84-90
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• 2011

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt $V_{max}$ referring enzyme activity ($E_0$) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

• 한국물환경학회지
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• 제18권2호
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• pp.159-168
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• 2002

A lab-scale Reverse Osmosis(RO) membrane reactor was installed to investigate the membrane permeability, characteristics of membrane fouling at each conditions, and performance of elimination at different trans-membrane pressure(TMP) in the liquid fertilizer accumulated system. Experimental setup was divided to three different TMP conditions. As a result of experiment, permeability of RO membrane was proportional to the increase of TMP and temperature. After experiment was completed, two types chemical cleaning(remove the organic foulant and inorganic foulant) was done, and recover rate of permeability was each 99.8, 99.7 and 99.7%, respectively. From this experimental data, membrane fouling could be determined that the most of it was recoverable in this system, and major reason of fouling was concentration polarization. Elimination rate of solute substance in the liquid fertilizer indicated very stable(above 99%), except ammonia nitrogen, and the most stable elimination rate was investigated at the highest TMP condition (Run 3).

• Asian-Australasian Journal of Animal Sciences
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• 제7권1호
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• pp.57-61
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• 1994

The study was conducted at low lying areas in Pabna Sirajgong districts of Bangladesh. To observe the potentiality of bio-mass production two trials were conducted. In first trial maize intercropped with Khesari taking 15 experimental plots of each size $5m{\times}5m$ were arranged in 5 blocks having homogenous soil characteristics. The study showed that the bio-mass yield of sole maize and sole Khesari were 35.25 t/ha. and 56.80 t/ha. respectively and there was a significant difference (p < 0.01) among them. The results also showed that bio-mass yield of maize and Kherasi was higher ($70.04{\pm}6.25t/ha$, $98.88{\pm}10.77t/ha$ and $80.56{\pm}9.5t/ha$) compared to sole maize and sole Khesari and land equivalent ratio was also lower. For second trial, one hectare of land was divided into 16 experimental plots with 4 replications in each plot. Four levels of urea (0 kg/ha, 30 kg/ha, 45 kg/ha, and 60 kg/ha.) were applied to experimental plot. The seed rates were 98.8 kg/ha (farmer's practice), 86.45 kg/ha, 74.1 kg/ha and 61.75 kg/ha. average bio-mass yield of matikalai at different seed rates along with urea fertilizer ranged from 38.49 t/ha, to 65.35 t/ha. the highest seed rate along with highest fertilizer also correspond to the peak production (65.35 t/ha) and the lowest seed rate (61.75 kg/ha) along with the lowest fertilizer rate (30 kg/ha.) showed lowest production (38.49 t/ha.). Here, it was found that the bio-mass yield of matikalai increased with the incremental amount of seed, indicating significant effect (p < 0.05) of seed rates on the bio-mass yield of matikalai. On the other hand, fertilizer doses in different treatment combinations had significant effect (p < 0.05) on bio-mass yield. Two levels of seed rates at zero level of fertilizer were recommended : 86.45 kg/ha for the resource rich farmers and 61.75 kg/ha for the resource poor farmers.

• 한국초지조사료학회지
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• 제23권2호
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• pp.77-80
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• 2003

본 시험은 제주지역에서 지렁이(100%) 시비량 차이(0, 100, 200, 300, 400, 500 및 600kg/10a)에 따른 신나리 열무의 생육반응 및 수량을 검토하고, 지렁이분 적정시비량을 구명하기 위하여 2002년 11월 7일부터 2003년 3월 8일까지 시험하였다. 초장은 무비구에서 500kg/10a 시비구까지 30.3cm에서 37.77cm로 커졌고, 그 이상의 시비구에서는 작아졌으나 200kg/10a에서 600kg/10a 시비구까지는 유의한 차이가 없었다. 엽수, 엽폭 및 근경은 초장 반응과 비슷한 경향이었다. 근장은 처리구간에 큰 차이가 없었고, 엽록소 함량은 시비량이 증가함에 따라 증가하였다. 총생체중(지상부중+근중)은 무비구에서 200kg/10a 시비구까지는 2,949kg/10a에서 4,561kg/10a로 유의하게 증가되었고, 300kg/10a에서 500kg/10a 시비구까지는 5,096kg/10a에서 5,707kg/10a로 증가되었다가 600kg/10a 시비구에서 4,873kg으로 감소되는 경향이었다. 그러나 300kg/10a 시비구에서 600kg/10a 시비구까지는 통계적으로 유의한 차이가 없었다. 지상부 생체중과 근중은 총생체중 반응과 비슷한 경향이었다.

• 한국작물학회지
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• 제46권4호
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• pp.289-295
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• 2001

Experiments were conducted to find out the optimum level of slow release N fertilizers when total amounts of nitrogen required throughout the growing season in paddy were applied in the soil of seedling box. To evaluate the emergence rate and growth of rice seedlings, five levels of Meister (MS) 10, MS S10, and latex coated urea (LCU) which are equivalent to 0, 40, 60, 80, and 100kg N h $a^{-l}$ were mixed in soil of the seedling box. Emergence rate differed depending on the fertilizers and N levels; in MS 10 plots the emergence rate was 40.8% at 40kg N h $a^{-l}$ and no seedlings were emerged at the higher levels, in MS S10 plots higher than 80% at all the N levels, and decreased with the N levels from 70.0% at 40 kg N h $a^{-l}$ to 59.5% at 100kg N h $a^{-l}$ of LCU. Seedling started to wilt at 40 kg N h $a^{-l}$ of MS 10 and 80 and 100 kg N h $a^{-l}$ N of LCU on the 8th day after sowing, while seedling growth was normal at all the levels of MS S10. Field performance of rice was evaluated at the 0, 30, 60, 90, 120kg N h $a^{-l}$ of MS S10 applied in the soil of seedling box and N was not applied in paddy. Grain yield at 90 and 120kg N h $a^{-l}$ of MS S10 was similar to conventional urea split application (120 kg N h $a^{-l}$), but significantly higher compared to 30 and 60kg N h $a^{-l}$ of MS S10. Fertilizer N recovery decreased with N levels and the N recovery at 90 kg N h $a^{-l}$ of MS S10 and conventional urea split application were 62.2 % and 44.2%, respectively, with similar grain yield. The optimum level of MS S10 to be applied in seedling box seems to be about 90 kg N h $a^{-l}$ considering grain yield, price of fertilizer, labor applying fertilizer, and fertilizer N recovery.d fertilizer N recovery.

• 한국토양비료학회지
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• 제20권3호
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• pp.285-299
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• 1987

질소비료(窒素肥料)의 효율(效率)을 높임에 있어서 시용시기(施用時期)와 시비위치(施肥位置)는 두가지 중요(重要)한 기술적(技術的) 수단이다. 이 두 수단들 가운데 어떤 것이 더 중요(重要)하냐 하는 것은 시비량(施肥量)에 따라 다르다. 즉 시비량(施肥量)이 적을 때에는 분시회수(分施回數)를 늘림보다는 기비(基肥)를 어떤 위치(位置)에 시용(施用)하느냐가 중요(重要)하고, 시비량(施肥量)이 많을 때에는 시비위치(施肥位置) 못지않게 어떻게 분시(分施)하느냐도 중요(重要)하다. 대체(大體)로, 아직 열대지역(熱帶地域)의 농가(農家)에서는 시비량(施肥量)이 낮은 편이므로, 분시회수(分施回數)보다는 시비위치(施肥位置)를 적절하게 하는 것이 중요(重要)하다. 이제까지 얻어진 연구결과(硏究結果)들을 검토해 보면, 질소비료(窒素肥料)의 시비위치(施肥位置)에 있어서, 수도작(水稻作)에서는 심층시비(深層施肥)가 유효(有效)하고, 밭농사에 있어서는 토층중(土層中) 측조시비(側條施肥)가 유효(有效)하다는 결론(結論)을 도출(導出)할 수 있다. 그러나 수도작(水稻作)에 있어서의 심층시비(深層施肥)는 적절(適切)한 시비기(施肥機)가 사용(使用)되지 않는 한(限), 농가(農家)에서의 실천(實踐)이 특(特)히 어렵다. 밭농사의 경우 토층중(土層中) 측조시비(側條施肥)는 수도작(水稻作)에서의 심층시비(深層施肥)에 비(比)해 실천(實踐)하기가 비교적(比較的) 용이(容易)하다. 수도작(水稻作)에서 완전(完全)한 심층시비(深層施肥)가 곤란(困難)한 조건(條件)에서는 차선책(次善策)으로 전층시비(全層施肥)를 권장해 봄직하다. 금후(今後)의 연구방향(硏究方向)으로, 수도용(水稻用) 간이(簡易) 심층시비기(深層施肥機)의 개발(開發)과, 농민이 쓰기에 편(便)하고 효율(效率)이 높은, 그러면서도 생산(生産)이 까다롭지 않은 신질소비료(新窒素肥料)의 개발(開發)을 들수 있을 것이다.

• 한국작물학회지
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• 제46권2호
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• pp.125-129
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• 2001

Eight vermiculite-based root media prepared with addition of complete fertilizer (2 g/L; N-$P_2$$O_5$-$K_2$O, 10-10-14) for potatoes (Solanum tuberosum L.) and a commercial root medium were evaluated in 2000 to develop the root media suitable for potato plug seedling production. The eight media consisted of various ratios of vermiculite, perlite, peatmoss, and compost. In addition, four rates (0, 1, 2, or 4 g/L) of the complex fertilizer for potato were added to a root medium (70% vermiculite, 10% perlite, 10% peat moss, and 10% compost by volume) to determine the optimum addition rate of the complex fertilizer for plug seedlings. Compost addition to the media increased plant height, the number of leaves per plant, and top and root fresh weight of 15-day old plug seedlings. The seedlings raised in root media containing compost produced significantly higher total tuber yield. Addition of the complex fertilizer to root media enhanced seedling growth and increased the number of tubers per plant and tuber yields. The results suggest that root media containing 50% vermiculite, 0 to 20% peat moss, 10% perlite, 20 to 40% compost, and 2 g/L complex fertilizer for potato appear suitable for potato plug seedling production.

• Environmental Engineering Research
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• 제21권1호
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• pp.29-35
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• 2016

This study evaluated the fertilizing value of struvite deposit recovered from swine wastewater in cultivating lettuce. Struvite deposit was compared to complex fertilizer, organic fertilizer and compost to evaluate the fertilizing effect of struvite deposit. Laboratory pot test showed that the struvite deposit better enhanced lettuce growth in comparison to commercial fertilizers. It was revealed that the growth rate of lettuce was simultaneously controlled by phosphorus (P) and magnesium (Mg). Moreover, nutrients such as nitrogen (N), P, K, calcium (Ca) and magnesium (Mg) were abundantly observed in the vegetable tissue of struvite pot. Meanwhile, struvite application led to the lower accumulation of mercury (Hg), lead (Pb), chromium ($Cr^{6+}$) and nickel (Ni). In addition, no detection of cadmium (Cd), arsenic (As) and nickel (Ni) in the lettuce tissue was observed in struvite application pots. The experimental results proved that the optimum struvite dosage for lettuce cultivation was 0.5 g struvite/kg soil. The column experiments clearly showed that ammonia nitrogen was more slowly released from struvite deposit than from complex fertilizer. Consequently, it was concluded that the struvite deposits recovered from swine wastewater were effective as a multi-nutrient fertilizer for lettuce cultivation.

• 아시안잔디학회지
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• 제11권2호
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• pp.97-104
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• 1997

The objective of this study was to observe the differences in growth of creeping bentgrass turf to 'polymer coated urea fertilizer' and 'uncoated urea fertilizer', and to analyze durability of fertilizer effect with the 'polymer coated urea'. The experiment was initiated on June 3, 1996, at the Iowa State University Horticulture Research Station, north of Ames, Iowa. The experiment was conducted on an area of 'Penneagle' Creeping bentgrass(Agrostis palustris) maintained at fair-'way mowing height (1.3cm). The study was repeated at the same arrangement beginning on July 25, 1996. Visual quality data, clipping fresh and dry weight, and nitrogen(N) content in the clippings were taken weekly. Quality of the turf increased with increasing N rate. While quality ratings were higher for turf receiving polymer coated urea than for turf receiving uncoated urea at several times following treatment, but not significant. Fresh and dry clipping weights were quite variable during the trial. Visual quality rating and clipping yields improved with increasing rates of N but these differences were not statically significant between polymer coated and uncoated urea treatment. The durability of fertilizer efficiency in polymer coated urea was not last longer compare with uncoated urea from two weeks after treatment. Higher rates of N application increased the concentration of N in tissue but no significant differences between turf plots receiving polymer coated and uncoated urea. Key words: Polymer coated urea, Creeping bentgrass, Fertilizer, Turfgrass.