• Journal of Korean Society on Water Environment
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• v.34 no.3
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• pp.316-327
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• 2018

Liquid fertilizers made from livestock manure contain high concentrations of nitrogen and phosphorus and thus are used as a fertilizer. However, excessive use of liquid fertilizer causes eutrophication of agricultural land and nonpoint source pollution. In this study, as a means of lowering the nutrient concentrations, struvite ($MgNH_4PO_4{\cdot}6H_2O$) production from the liquid fertilizer was investigated. When liquid fertilizers produced in Gyeonggido were analyzed, its characteristics differed by region and season, but the phosphorus concentration was commonly lower than that of nitrogen. When $K_2HPO_4$ and $MgCl_2$ were added to the liquid fertilizers, the optimal pH for struvite formation was pH 9.5. For environmentally friendly sources of magnesium and phosphate, ferronickel slag (FNS) and sewage sludge ash (SSA) were suspended in deionized water and extracted by sulfuric acid with various mass ratios. The optimum conditions for extracting FNS and SSA were 4.0 M sulfuric acid and 0.35 mass ratio of sulfuric acid to sewage sludge ash, respectively. For forming struvite, 0.233 L of SSA leachate (SSAL) was added into 0.3 L of liquid fertilizer containing 2,586 mg/L of ammonia and 110 mg/L of phosphate, pH was then adjusted to pH 9.5 using 10 M of NaOH. Afterwards 0.333 L of FNS leachate (FNSL) was added to this mixed solution. After a reaction for 1 hr at room temperature, the remaining concentrations of magnesium, ammonium, and phosphate were less than 50 mg/L, 500 mg/L and 150 mg/L, respectively, and 30 g of precipitates were obtained, most of which were struvite.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.404-411
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• 1988

This study was conducted to find out the optimum fertilizer level for two job's tear varieties. Heuksuk and Ewon from local cultivars at 18 compositions of fertilizer levels. Plant height was longest. number of tillers and leaves were increased. stem diameter was thickest, 100 grains weight. stem and grain yield were heaviest at the compositions of fertilizer amounts with N-P$_2$O$\sub$5/-K$_2$O were 18-9-9$\^$kg/ (3-2-2) per 10a. Plant height. number of tillers and leaves. stem diameter, 100 grains weight and stem yield showed significant difference between grain yield and showed positive correlation. Judging from the results reported above, in optimum fertilizer amounts for N-P$_2$O$\sub$5/-K$_2$O seemed to he 18-9-9$\^$kg/ (3-2-2) per 10a.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.119-131
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• 2017

This study evaluated the feasibility of recovering and recycling nitrogen (N) and phosphorus (P) from livestock excreta as struvite ($MgNH_4PO_4{\cdot}6H_2O$) in South Korea. Our experimental results showed that struvite precipitation was a very effective way to recover N and P from livestock excreta. Moreover, our study demonstrated that struvite precipitates from livestock excreta (SPL) contain higher concentrations of N, P, and magnesium (Mg) as compared to compost and liquid manure from livestock excreta. In addition, although SPL contain high concentrations of copper (Cu) and zinc (Zn), they meet the fertilizer criteria for concentrations of heavy metals. In South Korea, SPL cannot currently be used as a fertilizer due to legal constraints. Legal permission for SPL use would offer greater choice in livestock excreta management. In conclusion, recovery and recycling of N and P from livestock excreta as struvite can be an effective tool for managing nutrients in livestock excreta.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.471-477
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• 2010

Although the roles of calcium in plant are widely known, little is known about on an antagonistic effect of macro elements, oxalate biosynthesis and main shape of crystal in cucumber plant organs. Seeds of cucumber (Cucumis sativus cv. Ijoeunbackdadagi) were germinated in perlite tray supplied with distilled-deionized water. Seedlings were transplanted into aerated containers with a half strength of Ross nutrient solution. Ca levels treated in media were as follows; No-Ca, $Ca(NO_3)_2$ 0.25, 1.25 and 2.5 mmol $L^{-1}$, and $Ca(NO_3)_2$ 2.5 mmol $L^{-1}$ + $CaCl_210$, 25 and 50 mmol $L^{-1}$. Ca-deficient and -excessive conditions severely reduced cucumber growth, as compared to the control, and adversely affected an accumulation of macro elements (N, P, K, and Mg). Calcium favorably induced oxalate (acid-soluble) synthesis in leaves and roots of cucumber plant, but not in stem. Acid-soluble oxalate contents in leaves proportionally increased with Ca supply levels (0.91, P<0.001), however, this pattern was not observed in stem and roots. Ca-oxalate crystal formation and compositional analysis were examined using SEM-EDS technique in cucumber leaves. The main type of crystal revealed a prismatic crystal and main components were Ca, Na and Cl.

• Korean Journal of Environmental Agriculture
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• v.33 no.1
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• pp.44-51
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• 2014

BACKGROUND: Water quality of rural areas are susceptible to agricultural nutrient input and supply such as chemical fertilizer and livestock manure. This study was conducted to evaluate the usefulness of nutrient (N and P) indices in understanding spatial variations of water quality across Chonnam province which is a typical agricultural region in Korea. METHODS AND RESULTS: The nutrient indices including chemical fertilizer supply, livestock manure production, and nutrient balance were correlated with water quality data (T-N, T-P, BOD, and COD) for the twenty-two districts of the province. Concentration of T-N were positively correlated with chemical fertilizer supply, livestock manure N production, and nutrient balance (P<0.05 or P<0.01). Meanwhile, T-P concentration was not correlated with these nutrient indices; however, there was a tendency that T-P concentration increases with livestock manure P production (P=0.06) and with nutrient balance (P=0.09). These results suggest that T-N concentration is susceptible to both chemical fertilizer and livestock manure; whereas T-P is likely to be affected by livestock manure rather than chemical fertilizer. The concentrations of BOD and COD were also positively (P<0.05 or P<0.01) correlated with livestock manure production. CONCLUSION: This study shows the usefulness of nutrient indices in understanding spatial variations of water quality and suggests that livestock manure rather than chemical fertilizer can be a more critical water pollution source and thus highlights the need for more attention to livestock manure treatments for rural water quality management.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.218-224
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• 2003

Magnesium hydroxide, which recently registered as a Mg fertilizer, is greatly different from magnesium sulfate in its solubility and effect on soil pH. In this study, the effects of magnesium hydroxide and magnesium sulfate on growth of chinese cabbage were compared at the application rate of $300kg\;MgO\;ha^{-1}$ in a Gyeongsan clay loam soil. Although magnesium hydroxide was effective in increasing number of leaf and fresh weight, overall effects of magnesium hydroxide and magnesium sulfate on the growth of chinese cabbage were not significantly different ($p{\leq}0.05$). Comparing the two magnesium fertilizer treatments, magnesium content of chinese cabbage was relatively higher in the magnesium sulfate treatment in the early stage of growth, but it was higher in the magnesium hydroxide treatment at harvest. Contents of Ca, P, and K in chinese cabbage were relatively higher in the magnesium hydroxide treatment than those in magnesium sulfate treatment. But, the differences in nutrient uptakes by chinese cabbage between the treatments were not significant ($p{\leq}0.05$). Therefore, magnesium hydroxide is expected to be used with nearly the same effects on crops as magnesium sulfate at the same application rate of Mg. Soil pH in the treatment of magnesium sulfate was lower than that of control treatment, but magnesium hydroxide could increase pH. Magnesium hydroxide can be used preferentially in acid and/or sandy soils, where magnesium sulfate can induce further soil acidification and leaching loss of Mg is often a severe problem.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.273-278
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• 2002

An efficient low-input system (LIS) for fertiliser use in rice cultivation is necessary to reduce fossil energy use and pollution. Japanese people like Japonica rice, especially cv. Koshihikari. However, it has very low lodging resistance in Japanese weather condition. Our objective was to develop a LIS with the minimum sacrifice of grain yield in rice. Koshihikari was grown using conventional fertilization as a control (CON) with 4 g N $m^{-2}$., 8g $P_2$ $O_{5}$ $m^{-2}$ and 8 g $K_2$O $m^{-2}$ as a basal fertilizer dressing. It was compared with a low fertilizer treatment (LF) with only 4 g $P_2$ $O_{5}$ $m^{-2}$ as a basal dressing in the first year and no basal phosphorus fertilizer in the second year. Chopped rice straw was incorporated into the soil before the cropping season in both years. Fertilizer of 4 g N $m^{-2}$ was top-dressed at 15 days before heading in CON plots and 30 days before heading in LF plots in both years. Lodging was significantly less in LF than in CON plots, however, no rice straw effect was found in low fertilized condition. Grain yields in LF plots were reduced by 15-16% below those of CON plots. Lower yields in LF plots were associated with a reduced number of spikelets per unit area. However, big spikelet size was acquired in LF by 10 days earlier N top dressing than CON plots. A close relationship was found between spikelet numbers and N content of the plant at heading, and between grain yield or shoot dry weight and N content of the plant at maturity. Regardless of the fertilizer application methods, N use efficiency for the number of spikelets, final total dry matter and grain yield was essentially identical among fertilizer treatments. The reduced growth and yield in the LF plots resulted from low absorption of nitrogen. Conclusively, LIS can drastically reduce chemical fertilizer use and facilitate harvest operations by reducing lodging with some yield reduction..

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1016-1022
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• 2011

Application of silicate fertilizers is typically practiced with several year's interval to amend soil quality and improve rice productivity at the paddy field in Korea. Most of silicate fertilizers applied in Korea is slag-originated silicate fertilizer. Some water soluble silicate fertilizers are manufactured and commercially available. The objective of this study was to assess changes of soil chemical properties in paddy field by applying slag-originated silicate fertilizer and water soluble silicate fertilizer. Field experiment was conducted on a silt loam paddy soil, where four levels of each silicate fertilizer were applied in soil at the rate of 0, 1, 2, 4 times of the recommended levels. Application of slag-originated silicate fertilizer increased soil pH, while no significant pH increase occurred with the treatment of water soluble silicate fertilizers. Soil pH increased 0.4~0.5 with the 1 time of recommended level of slag-originated silicate fertilizer. Available $SiO_2$ contents also significantly increased with the treatment of slag-originated silicate fertilizer at 15 and 35 days after treatment, while decreased after 60 days after treatment possibly due to rice uptake. Exchangeable Ca, Mg and available phosphate contents in soil increased with application of slag-originated silicate fertilizer, while a little increases for them were shown with the application of soluble silicate fertilizer. $SiO_2$/N ratios in rice straw for 1 time of recommended level of slag-originated silicate fertilizer was 11.5, while that of control was 8.4, which was much lower value. Throughout this study, soil application of slag-originated silicate fertilizer enhanced soil chemical properties, while water soluble silicate fertilizer application in soil needs further study resulting in a little effects on soil property.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.2
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• pp.70-75
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• 1981

The ammonia volatilization from two different soils, an acidic normal soil and a neutral tidal soil applied with different nitrogen sources was investigated through a laboratory incubation experiment conducted at about $30^{\circ}C$ for 18 days. Results obtained were summerized as follows; 1. The ammonia volatilizat ion was increased by the urea application that increased soil pH. 2. Ammonium sulfate and ammonium chloride did not raise reduced soil pH over 7.30 and showed little ammonia volatilization keeping the $pK_b$ value of 4.72-3 3. An organic fertilizer (Miweon Co. made) raised pH of the tidal land soil little more than ammonium sulfate or ammonium chloride ; however, it did not increase the ammonia volatilization as much as from other fertilizer treatment plots of the same pH, which may mean that the organic fertilizer is effective in reducing ammonia volatilization. 4. It seemed that easier volatilization of ammonia from urea may occor in ordinary soil low in original pH than from tidal soil by the application of urea which may mean that if the pH of soils are the same, greater volatilization would result from the former than the latter. 5. Application of raw straw to tidal soil lowed pH and reduced ammonia volatilization.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.436-441
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• 2015

The chemical properties of paddy fields in Gyeonggi province were monitored every 4 years from 1999 to 2015 in order to provide basic information for soil fertility management of paddy fields. In 2015, the soil chemical properties of paddy fields were 5.9 in pH, $23g\;kg^{-1}$ in organic matter (OM), and $84mg\;kg^{-1}$ in available phosphate (Avail. $P_2O_5$). Exchangeable (Exch.) potassium (K), calcium (Ca) and magnesium (Mg) were 0.30, 5.1 and $1.3cmol_ckg^{-1}$, respectively, and available silicate (Avail. $SiO_2$) was $129mg\;kg^{-1}$. In the long-term analysis, the contents of Avail. $SiO_2$, Exch. Ca and pH of paddy soils showed increasing tendency. However, Avail. $P_2O_5$ and Exch. K tended to decrease, and there were no significant changes in the contents of OM and Exch. Mg. Paddy soil within appropriate pH range increased from 44% in 1999 to 76% in 2003, 84% in 2007, 63% in 2011, and 80% in 2015. But soil within appropriate range of Exch. Ca tended to decrease, showing 36% in 1999, 42% in 2003, 38% in 2007, 37% in 2011 and 32% in 2015. In case of Avail. $SiO_2$, soil within appropriate range increased from 14% in 1999 to 17% in 2003, 18% in 2007, 16% in 2011, and 31% in 2015. As a result, paddy fields with less in nutrient level need to be more fertilized based on soil analysis. And the application of silicate fertilizer is strongly recommended to those of paddy fields in need. Also soil management such as the cultivation of green manure crop or application of rice straw will be necessary to increase the organic matter content of paddy soil.