Yeon-Kyu Sonn

Status and Changes in Chemical Properties of Paddy Soil in Korea

Soil chemical properties of agricultural soils in Korea were investigated at four-years interval in order of paddy, plastic film house, upland, and orchard soils since 1999. Paddy soil samples were taken from the surface 15 cm at 4,047, 2,010, 2,110 and 2,110 sites in all provinces of South Korea in 1999, 2003, 2007 and 2010, respectively. Soil chemical properties in Korea except Jeju province were measured. Soil pH and exchangeable calcium and available silicate contents increased with increasing the application rate of silicate fertilizer and with decreasing its application interval. Soil organic matter content also increased from in 1999 to in 2011. Average concentration of available phosphate in 2011 was higher than the upper limit of its optimal range for rice cultivation. However, exchangeable magnesium and available silicate contents were below the lower limit of their optimal ranges, which were 80% and 92% of them, respectively.

Responses of Lactuca Sativa (Lettuce) to Fertilization Rates at Various Soil Moisture Conditions at Protected Cultivation

This research was performed to test the hypothesis that the optimal fertilization rate for lettuce is various with soil moisture conditions. The experiment was conducted under a rainfall-intercepted facility in Suwon, South Korea from 2002 to 2003. Soil was irrigated at 30, 50, or 80 kPa of soil moisture tension at 15 cm soil depth in 2002 spring and fall and 20, 30, 50, or 80 kPa in 2003 spring. Fertilization was performed with four levels in spring for both years: none, 0.5, 1.0, and 1.5 times of the recommended N, P, and K fertilization rate. The irrigation amount increased with decreased irrigation starting point as soil moisture tension. The maximum yield was found at the lowest soil moisture tension in spring while irrigation at 50 kPa resulted in the greatest yield in fall. The yield responses of lettuce to fertilization rates were various with soil moisture condition. In spring, maximum yield was found at 1.0 or 1.5 times of the recommended fertilization rate at 20, 30, and 50 kPa irrigation while 0.5 or 1.0 times of fertilization rate resulted in the maximum yield in fall. Especially for 80 kPa irrigation in 2003 spring, yield was decreased by fertilization. It suggested that the optimum fertilization rate for lettuce is affected by soil moisture condition and that lower fertilization rate should be suggested when soil is managed in drier condition.

Implication of Soil Minerals on Formation of Impermeable Layers in Saprolite Surface-Piled Upland Fields at Highland

Farmers in highlands in South Korea pile up 20 to 30 cm of saprolites, mostly granite- or granitegneiss-weathered materials, on surface of arable lands every three to five years to compensate eroded soil and sometimes to discontinue soil-borne diseases. Immediate increases of infiltration and percolation rates are expected with coarse textured saprolites while soil drainage becomes poorer in a long-term. In this study, we analyzed mineralogical characteristics and micro-morphology of plow pan to investigate processes making impermeable layers. Soil samples were collected from plow pan, usually located at approximately 20 cm soil depth and at the lower part of piled saprolites, in arable lands in Hoenggye 5-ri, Daekwanryeong-myeon, Gangwon-do (N37.7, E128.7) in which saprolites were added 2, 4, and 8 years ago; saprolites were transported from similar areas. The saturated hydraulic conductivity decreased over time. Based on soil thin section pedography, quartz and feldspar accounted for a majority of minerals. The size of feldspar decreased and macropores became filled with clay or silt particles over time, which implies that macropores were packed with particles weathered from feldspar. The X-ray diffraction (XRD) analysis indicated that intensity of feldspar decreased over time and the reverse was true for kaolinite and illite, indicating that feldspar and mica weathering induced formation of kaolinite and illite. Conclusively, deteriorated drainage by formation of impermeable layers in farms with piled saprolites was caused by accumulation of clay minerals such as kaolinite and illite in macropores; illite and kaolinite can be formed by weathering of mica and eldspar, respectively.

Nutrient Balances and Soil Properties Affected by Application of Soybean and Barley Residues

An accurate analysis of nutrient balance in different cropping systems is necessary for improving soil fertilities, causing higher crop yields and quality. This study was carried out to investigate the nutrient balance, changes in soil properties, and their effects on crop yield in long-term field cultivation under mono- and rotation-cropping systems (MCS and RCS, respectively). The analytical results of the soil properties showed that the application of mineral fertilizers alone in the MCS leads the reduction of soil CEC, exchangeable Ca, and microbial biomass C and N. Compared with the MCS of soybean, the RCS of soybean and barley significantly improved the soil properties, which increased crop yield. It might be due to the barley residue added to the RCS soil. Mean nutrient balances for 4 years were ?55.9 kg N, +34.7 kg P₂O?, and ?0.3 kg K₂O ha -1 for the MCS and +19.7 kg N, +107.4 kg P₂O?, and ?48.6 kg K₂O ha -1 for the RCS, respectively. These nutrient imbalances mean that conventional fertilizer recommendations were inadequate for maintaining soil nutrient balance. From these results, we can conclude that the crop rotation may change comprehensive physical, chemical, and biological soil properties. These changes could affect the nutrient balance and then the crop yield.

Sulphamethazine in poultry manure changes carbon and nitrogen mineralisation in soils

ABSTRACT Antibiotics are newly emerging organic pollutants in manure, soil, vegetables and water. Animal manure application might be leading to the accumulation of antibiotics in the farmland. However, the effect of sulphamethazine (SMZ) on the soil microbial community was scarcely investigated. This study was aimed to evaluate the impact of SMZ on poultry manure, on the structure and function of microbial community, carbon mineralisation, and changes in nitrogen forms in soil via an incubation experiment lasting 56 d. The treatments consisted of poultry manure at 1% wt (PM), PM containing 20 mg kg−1 SMZ (PM + 20SMZ) and PM containing 100 mg kg−1 SMZ (PM + 100SMZ), along with the untreated soil (control). Solid phase extraction was performed to measure the SMZ concentration in soils using high-pressure liquid chromatography. The cumulative CO2-C was increased in all treated soils over the incubation period compared to the control. The PM + 100SMZ had the highest increase in cumulative CO2-C from the soil at 56 d of incubation. The treatment of PM + 20SMZ showed a short-term decrease in nitrification rate in the soils at 1 d by altering the microbial community composition with 17% dissimilarity and decreasing the abundance of bacteria compared to PM-treated soil. The PM + 100SMZ increased C mineralisation in the soil.

Impacts of Soil Texture on Microbial Community of Orchard Soils in Gyeongnam Province

Soil management for orchard depends on the effects of soil microbial activities. The present study evaluated the soil microbial community of 25 orchard (5 sites for sandy loam, 7 sites for silt loam, and 13 sites for loam) in Gyeongnam Province by fatty acid methyl ester (FAME) method. The average values for 25 orchard soil samples were 270 nmol g -1 of total FAMEs, 72 nmol g -1 of total bacteria, 34 nmol g -1 of Gram-negative bacteria, 34 nmol g -1 of Gram-positive bacteria, 6 nmol g -1 of actinomycetes, 49 nmol g -1 of fungi, and 7 nmol g -1 of arbuscular mycorrhizal fungi. In addition, silt loam soils had significantly low ratio of cy17:0 to 16:1ω7c and cy19:0 to 18:1ω7c compared with those of loam soils (p < 0.05), indicating that microbial activity increased. The average soil microbial communities in the orchard soils were 26.7% of bacteria, 17.9% of fungi, 12.6% of Gram-negative bacteria, 12.5% of Gram-positive bacteria, 2.5% of arbuscular mycorrhizal fungi, and 2.2% of actinomycetes. The soil microbial community of Gram-negative bacteria in silt loam soils was significantly higher than those of sandy loam and loam soils (p < 0.05).

Comparison of Soil Pore Properties between Anthropogenic and Natural Paddy Field Soils From Computed Tomographic Images

Human influence on soil formation has dramatically increased with human civilization and industry development. Increase of anthropogenic soils induced researches on the anthropogenic soils; classification, chemical and physical characteristics of anthropogenic soils and plant growth from anthropogenic soils. However there have been no comprehensive analyses on soil pore or physical properties of anthropogenic soils from 3 dimensional images in Korea. The objectives of this study were to characterize physical properties of anthropogenic paddy field soils by depth and to find differences between natural and anthropogenic paddy field soils. Soil samples were taken from two anthropogenic and natural paddy field soils; anthropogenic (A_c) and natural (N_c) paddy soils with topsoil of coarse texture and anthropogenic (A_f) and natural (N_f) paddy soils with topsoil of fine texture. The anthropogenic paddy fields were reestablished during the Arable Land Remodeling Project from 2011 to 2012 and continued rice farming after the project. Natural paddy fields had no artificial changes or disturbance in soil layers up to 1m depth. Samples were taken at three different depths and analyzed for routine physical properties (texture, bulk density, etc.) and pore properties with computer tomography (CT) scans. The CT scan provided 3 dimensional images at resolution of 0.01 mm to calculate pore radius size, length, and tortuosity of soil pores. Fractal and configuration entropy analyses were applied to quantify pore structure and analyze spatial distribution of pores within soil images. The results of measured physical properties showed no clear trend or significant differences across depths or sites from all samples, except the properties from topsoils. The results of pore morphology and spatial distribution analyses provided detailed information of pores affected by human influences. Pore length and size showed significant decrease in anthropogenic soils. Especially, pores of A_c had great decrease in length compared to N_c. Fractal and entropy analyses showed clear changes of pore distributions across sites. The topsoil layer of A_c showed more degradation of pore structure than that of N_c, while pores of A_f topsoil did not show significant degradation compared with those of N_f. These results concluded that anthropogenic soils with coarse texture may have more effects on pore properties than ones with fine texture. The reestablished paddy fields may need more fundamental remediation to improve physical conditions.

Effects of Oyster Shell Lime on Barley Growth and Soil Microbe in an Upland Soil

Oyster shell has a high content of CaCO3 to be used as a acidic soil amendment. To enhance productivity of barley and soil microbe in an upland soil, oyster shell and calcium-magnesium carbonate were selected as a soil amendments in this study. A field experiment was treated no treatment (hereafter, control), oyster shell lime 3.09 Mg ha -1 and 2.38 Mg ha -1 , and calcium-magnesium carbonate 2.38 Mg ha -1 as amount of lime requirement in silt loam soil. The yield of barley from the oyster shell lime treatment was the highest. The protein content of barley was the highest of 11.1% in the calcium-magnesium carbonate, followed by 10.7% for the control, 10.6% for the oyster shell lime 3.09 Mg ha -1 , and 10.4% for the oyster shell lime 2.38 Mg ha -1 . Soil pH value was higher than that of control in harvesting stage. In addition, the population of soil bacteria was highest in oyster shell lime 2.38 Mg ha -1 , actinomycetes was highest in calcium-magnesium 2.38 Mg ha -1 .

Investigation of Heavy Metal Concentrations in Paddy Soils of Gyeongnam Province

Investigation of Heavy Metal Concentrations in Paddy Soils of Gyeongnam Province Young-Han Lee†, Yeon Kyu Sonn1†, and Yong Sik Ok* Gyeongsangnam-do Agricultural Research and Extension Services, Jinju 660-3703, Republic of Korea. National Academy of Agricultural Science, RDA, Suin-ro 150, Gwonseon-gu, Suwon 441-707, Republic of Korea. Biochar Research Center, Department of Biological Environment, Kangwon National University, Chuncheon 200-701, Republic of Korea.

Analysis of Catena on Representative Soils derived from Granite and Granite Gneiss

Soil catena can be characterized by some properties, such as drainage levels and soil textures. Characteristics of soil catena are different drainage levels from a summit to the direction of gravity and similar soil textures. Therefore this study was performed GIS (Geographic information system) and statistical analyses using perimeters from soil series in order to characterize quantitatively and objectively soil distributional properties in Korea. The total of 16 soil series from representative granite and granite gneiss originated soils were selected among inland soils from detailed soil maps (1:25,000 scale) in Rural Development Administration (RDA) and analyzed. After the detailed soil maps were merged by soil series unit, perimeters were measured from one soil series to neighboring soil series using functions of table join, merge, dissolve, buffer, and clip in ArcGIS (10.1). The covering ratio of each soil series unit was calculated from neighboring perimeters by soil series and applied to clustering analysis. Soils that were analyzed were the total of 16 soil series; 7 of sandy loam and 9 of clay loam. As a result, analyzed soil series adjoined complicatedly such as Hyocheon series adjoined 26 series and Jisan did 276 series. The results of the clustering analysis showed that soils were clustered by soil textures except a few soil series. This study applied only one property that was a length of neighboring soil series to GIS and statistical analyses. These results were compared to existing soil groups that were classified by new-soil taxonomy, texture, soil type and drainage level. It showed that these analyses can provide soil characteristics by soil texture. Based on this study, there is a need to investigate further objectively and quantitatively in statistical analyses of soil series.