Byong-Gu Ko

Wet Deposition of Heavy Metals during Farming Season in Taean, Korea

BACKGROUND: This experiment was conducted to investigate the distribution and burden characteristics of heavy metal in the rainwater sampled at Taean area, in the middle part of Korea, from April 2002 to October 2003. METHODS AND RESULTS: The relationship between concentration of heavy metal and other chemical properties in the rainwaters was also evaluated. Chemical properties in the rainwater were various differences with raining periods and years. It appeared that a weighted average pH values of rainwater was ranged from 5.0 to 5.1. Heavy metal con- centrations in the rainwater were ranked as Pb > Zn > Cu > Ni > As > Cr > Cd. As compared with heavy metal con- centrations of rainwater in 2002, Cu, Pb, and Zn were higher than other elements in 2003. There were positive corre- lation between major ionic components, such as NH4 + , Ca 2+ , Mg 2+ , K + , Na + , SO4 2- and NO3 - , and As, Cd, Zn, Cr, and Ni concentrations in rainwater. For heavy metal distribution of rainwater, the order of average enrichment factor was Cd > Pb > As > Cu > Zn > Ni > Cr, and these were relatively higher than the natural components such as Fe, Mg and Ca. The monthly enrichment factor were relatively high, from August to October at Taean. The monthly amount of heavy metal precipitation was high in the rainy season from July to August because of great influence of rainfall. CONCLUSION(s): The results of this study suggest that the heavy metals(Cd, Pb, As, Cu, and Zn) of rainwater is strongly influenced by anthropogenic sources rather than natural sources.

Correlation between Ground Water Quality Parameters and Total Coliforms in Livestock Farm

The main purpose of this study is to search the water factor which influences to occurrence of the total coliforms. Occurrences rate of the total coliforms and the E coli were 57.9% 10.5% in 2007 and 47.4%, 23.7% in 2008 respectively. According to the result which examines the correlation analysis and a regression analysis, most the water factor which is effect was (0.497, p(0.622, p. The predictable regression formula for appearance rate of the total coliforms was expressed as 0.462 + 0.028 [] - 0.644 [] - 8.889 [](R = 0.930, = 0.866, adjusted = 0.839, p](R = 0.622, = 0.387, adjusted = 0.351, p

Long-term Application Effect of Silicate Fertilizer on Soil Silicate Storage and Rice Yield

Monitoring of soil fertility and crop productivity in long-term application of silicate fertilizers is necessary to use fertilizers efficiently. This study was conducted to investigate effects of continuous application of silicate fertilizer for rice cultivation from 1969 to 2014. The treatments were no silicate fertilizer treatments (N, NC, NPK, and NPKC) and silicate fertilizer treatments (N+S, NC+S, NPK+S, and NPKC+S). The 46-yr input of 2 ton ha -1 yr -1 of silicate fertilizer increased pH 0.6 ~ 1.1 and exchangeable Ca 2.0~2.4 cmolc kg -1 in silicate fertilizer treatments (N+S, NC+S, NPK+S, and NPKC+S) compared with no silicate fertilizer treatments (N, NC, NPK, and NPKC) because silicate fertilizer included Ca component. Also, available silicate concentrations of silicate fertilizer treatments (N+S, NC+S, NPK+S, and NPKC+S) increased 169 mg kg-1 compared to no silicate fertilizer treatments. In Period II (’90~’14), the mean annual Si field balance varied from 62 to 175 kg ha -1 yr -1 in silicate fertilizer treatments, indicating continuous accumulation of soil Si. Silicon uptake and grain yield of rice had greater differences between N treatment and N+S treatment than other treatments. This showed that the application of silicate fertilizer had greater effect in nutrient-poor soils than in proper nutrient soils. Thus the application of silicate fertilizer led to improvement the fertility of soil and increasement of rice production for the lack of soil nutrients.

Effects of Rice Straw Compost Application on Exchangeable Potassium in Long-term Fertilization Experiments of Paddy Soils

In an experiment conducted at the research field of the National Institute of Agricultural Science, we investigated the effects of mineral fertilizer and rice straw compost on exchangeable potassium and K balances, and rice grain yield under a rice single system. The treatments were no fertilization (No fert.), inorganic fertilization (N), inorganic fertilizer (N, P, K) plus rice straw compost at rates of 7.5, 15.0, 22.5, and 30.0 ton ㏊ -1 (NPKC7.5, NPKC15.0, NPKC22.5, and NPKC30.0, respectively). The inorganic fertilizers (N, P, K) were added with standard fertilizer application rate in which nitrogen (N), phosphate (P₂O₅), and potassium (K₂O) were applied with 75∼150 ㎏ ㏊ -1 , 70∼86 ㎏ ㏊ -1 , 75∼86 ㎏ ㏊ -1 , respectively. Exchangeable potassium for NPKC15.0 NPKC22.5, and NPK30.0 treatments was higher by 0.05~0.19 cmolc ㎏ -1 than thatof NPKC7.5 treatment. Increasing levels of rice straw compost resulted in an increase in the K balance from –19.9 ㎏ ㏊-1 yr -1 (No fert.) to 41.9 ㎏ ㏊ -1 yr -1 at NPKC22.5 treatment and 62.9 ㎏ ㏊ -1 at NPKC30.0 treatment.Continuous application of rice straw compost with NPK fertilizers affected significantly the rice grain yields. The result of the study imply that the application of more than 22.5 ton ㏊ -1 of rice straw compost with NPK fertilizers are recommended as the best fertilization practice for enhancement of crop production and K supplying power of soil in the continuous rice cropping system.

Calculation of GHGs Emission from LULUCF-Cropland Sector in South Korea

The land use, land-use change, and forestry (LULUCF) is one of the greenhouse gas inventory sectors that cover emission and removals of greenhouse gases resulting from land use such as agricultural activities and land use change. Particularly, LULUCF-Cropland sector consists of carbon stock changes in soil, N2O emissions from disturbance associated with land use conversion to cropland, and CO2 emission from agricultural lime application. In this paper, we conducted the study to calculate the greenhouse gases emission of LULUCFCropland sector in South Korea from 1990 to 2014. The emission by carbon stock changes, conversion to cropland and lime application in 2014 was 4424, 32, and 125 Gg CO2-eq, respectively. Total emission from the LULUCFCropland sector in 2014 was 4,582 Gg CO2-eq, increased by 508% since 1990 and decreased by 0.7% compared to the previous year. Total emission from this sector showed that the largest sink was the soil carbon and its increase trend in total emission in recent years was largely due to loss of cropland area.

Effect of Soil Respiration on Light Fraction-C and N Availability in Soil Applied with Organic Matter

Soil respiration has been recognized as a key factor of the change of organic matter and fertility due to the carbon and nitrogen mineralization. In this study, we evaluated the effect of soil respiration on the light fraction-C and inorganic N content depending on temperature in soil applied with organic matter. Soil respiration was calculated by using total CO₂ flux released from soil applied with 2 Mg ha -1 of rice straw compost and rye for 8 weeks incubation at 15, 25, 35°C under incubation test. After incubation test, light fraction and inorganic N content were investigated. Rye application dramatically increased soil respiration with increasing temperature. Q 10 value of rye application was 1.69, which was higher 27% than that of rice straw compost application. Light-C and NO₃-N contents were negatively correlated to soil respiration. Light-C in rye application more decreased than that in rice straw compost with temperature levels. These results indicate that temperature sensitivity of soil respiration could affect soil organic mater content and N availability in soil due to carbon availability. Also, light fraction would be useful indicator to evaluate decomposition rate of organic matter in soil under a short-term test.

Effect of Winter Crop Cultivation on Soil Organic Carbon and Physico-chemical Properties Under Different Rice-forage Cropping Systems in Paddy Soil

Soil organic carbon plays an important role on soil physico-chemical properties and crop yields in paddy soil. However, there is little information on the soil organic carbon under different forage cultivation during winter season in rice paddy. In this study, we investigated the soil organic carbon and physico-chemical properties in 87 fields of paddy soil cultivated with Barley, rye, and Italian ryegrass (IRG) as animal feedstock during winter season. Organic carbon was 12.9, 14.3, and 16.9 g C kg -1 in soil with barley, rye, and IRG cultivation, respectively. Among rice-forage cultivation systems, the rice+IRG cropping system was 19.5% higher than in the mono-rice cultivation. Bulk density ranged from 1.17 to 1.28 g cm-3 irrespective of cropping systems, and had strongly negative correlation with the soil organic carbon in the rice+IRG cropping system. Carbon storage in rice+IRG cropping systems was average 29.6 Mg ha -1 at 15 cm of soil depth, which was 20.4 and 10.3% higher than those of barley and rye cultivation. Increasing carbon storage in paddy soil contributed to the fertility for following rice cultivation. This results indicated that IRG cultivation during winter season could be an alternative and promising way to enhance soil organic carbon content and fertility of paddy soil.

Effect of Food Waste Compost on Crop Productivity and Soil Chemical Properties under Rice and Pepper Cultivation

Food waste has recognized one of useful sources for potentially agricultural application to supply organic matter and nutrients in arable soil. However, there was little information on application of food waste compost related to the maturity and NaCl content in arable soil. This study evaluated the effect of food waste compost application on yield and fertility in soil under flooding and upland condition. The yields in rice and pepper cultivation decreased with increasing the rate of food waste compost application in soil (p -1 ) and pepper (204 g plant -1 ) were shown at 10 and 30 Mg ha -1 of food waste compost application, respectively. The N, P, and K contents in grain and plant residues increased by the application of food waste compost, there was no difference on Na/K ratio in plant tissue among the treatments. Application of food waste compost resulted in the increase of pH, EC, TC, available P contents in soil after crop harvest, especially, which was shown the increase of the CEC and exchangeable sodium percentage (ESP) contents in irrespective of water condition. In conclusion, application of food waste compost in soil was effective on the supply of the organic matter and nutrient. However, it might need caution to apply food waste compost for sustainable productivity in arable soil because of potential Na accumulation.

Evaluating Feasibility of Producing Fermented Organic Fertilizer with Vegetable Waste

Food waste (FW) has been recognized as a critical problem in Korea and many research was conducted to efficiently utilize or treat FW. Main purpose of this research was to evaluate a feasibility for producing fermented organic fertilizer with vegetable waste (VW). Three different organic materials (saw dust, coco peat, and waste mushroom media) were mixed with VW at the rate of 30, 40, 50% respectively. Total days of composting experiment were 35 days and each sub samples were collected at every 5 days from starting of composting. Result showed that inner temperature of composting was increased to 60±4°C within 5~10 days depending on varied organic materials and mixing ratio. Among different treatment, the highest increase of inner temperature was observed when 30% of saw dust was mixed with VW. After finishing composting experiment, maturity of each compost was evaluated with solvita and germination test. Maturity index (MI) of each treatment was ranged between 5~7 indicating that manufactured fertilizer was curing or finished stage. Calculated germination index (GI) was at the range of 57.83~101.16 depending on organic materials and mixing ratio. Both MI and GI showed that manufactured fertilizer was met for fertilizer criteria while control (VW only) was not adequate for composting. Overall, VW can be utilized for making organic fertilizer mixing with saw dust, coco peat and more research should be conducted to make high quality of organic fertilizer with vegetable waste.

Characteristics of Phosphorus Adsorption of Acidic, Calcareous, and Plastic Film House Soils

Continuous excessive application of phosphorus (P) fertilizer and manure in plastic film house soils can lead to an accumulation of P in soils. The understanding of P sorption by soils is important for fertilizer management. In this study, 9 samples were collected for acidic and calcareous soils as non-cultivated soil and plastic film house soils as cultivated soil Phosphorus sorption data of acidic soils fit the Langmuir equations, Freundlich equations in calcareous and plastic film house soils. In calcareous and plastic film house soils, the slope of isotherm adsorption changed abruptly, which could be caused P precipitation with CaCO₃. The calculated Langmuir adsorption maximum (S max ) varied from 217 to 1,250, 139 to 1,429, and 714 mg kg -1 for acidic soils, calcareous soils, and plastic film house soils with low available phosphate concentration, respectively. From this result, maximum P adsorption by the Langmuir equation could be regarded as threshold of P concentration to induce the phosphate precipitation in soil. Phosphate-sorption values estimated from one-point isotherm for acidic and calcareous soils as non-cultivated soils were comparable with the S max values calculated from the Langmuir isotherm.