Byung-Koo Ahn

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.

Effect of Liquid Pig Manure and Synthetic Fertilizer on Rice Growth, Yield, and Quality

We have researched the changes in nutrient content in each phase of fermentation in crops treated with liquefied pig fertilizer, and have determined the best method for applying livestock excrement to cultured crops. In the execution of this experiment, rice was cultivated to full maturity at a paddy field in Jeollabuk-Do Agriculture Research and Extension Services(Jeon-buk series) from 2007 to 2008. The rice plant nitrogen absorption quantity change, according to the growth stages of the cultivated rice, was 20.3% in the rice treated with the liquid pig manure and 22.2% the chemical fertilizer at highest congelation. The chemical fertilizer showed a higher absorption quantity than the liquid manure compost. The nitrogen density at highest congelation was 1.5% in the chemical fertilizer, and 1.8% in the pig manure liquid compost not a significant difference. The stem height at harvest time was 73.8 cm in the crops treated with the liquid pig manure compost. Those treated with the chemical fertilizer, yielded a height of 4.2 cm less than the crops treated with the liquid pig manure compost. The yield was 507 kg/10a in the liquid pig manure compost treated rice, compared with the chemical fertilizer, which showed a value of 1.2% lower. The protein content was 6.3% in the rice treated with the chemical fertilizer, but 6.4% in the rice treated with the liquid pig manure compost. This is not a significant difference. However, the lodging rice plant treated with the chemical fertilizer control showed a protein content of 6.8%, which was even higher than the normal rice. The head rice ratio in the brown rice and the polished rice ended up to be lower in the crop treated with the liquid pig manure than that treated with the chemical fertilizer, Quality, the palatability value, was similar in both groups. The above result indicate that, the effect of liquid pig manure compost corresponds to the effect of chemical fertilizer, when each are scattered uniformly.

Changes in Chemical Properties of Paddy Field Soils as Influenced by Regional Topography in Jeonbuk Province

We investigated the changes in chemical properties of paddy field soils at 300 different sampling sites containing 4 topography in Jeonbuk province, Korea. The soil samples were collected 43.0% from local valley and fans, 39.3% from fluvio-marine deposits, 15.0% from alluvial plains, and 2.7% from diluvium sites. The optimal values of soil properties in the total soil samples were as follows: 65.3% of total samples in soil pH value, 48.3% of total samples in cation exchange capacity (CEC) value, and 22.3% of total samples in available phosphorus content, whereas the deficient values of soil properties were 63.3% of total samples in soil organic matter (SOM) content, 75.7% of total samples in available silicate content, and 61.3%, 51.0%, and 59.3% of total samples in exchangeable , , and concentrations, respectively. There were different soil types in the paddy fields: that is, 34.4% immature paddy and 33.6% sandy paddy in the local valley and fans, 57.8% sandy paddy in the alluvial plains, 47.4% normal paddy in the fluvio-marine deposits, and 75.7% immature paddy in the diluvium. Soil textures were also different: 53.5% loam in the local valley and fans, 37.8% sandy loam in the alluvial plains, and 55.1% silty loam in the fluvio-marine deposits. Soil pH and SOM contents were not different among the different topographical sampling sites. However, the mean value of available phosphorus content, 224 mg , was exceeded optimal values in the diluvium. The contents of exchangeable cations were optimal in all the sites, except exchangeable contents in the local valley and fans. The contents of available silicate ranged between 112 and 127 mg in all the sites, which were lower than optimal value. In addition, soil pH values were proportionally correlated to the order of available silicate, exchangeable , , , CEC, and exchangeable . The contents of SOM were proportionally correlated to the order of CEC, available , exchangeable , and available silicate. The contents of heavy metals, Cd, Cr, Cu, Ni, Pb, and Zn, were only 10% of the threshold levels of the metals, and As content was about 20 to 30% of the threshold level.

Applications of Nutrient-Controlling and Growth-Regulating Chemicals to Enhance Yield of Once-Over Harvest Red Pepper (Capsicum annuun L.)

The cultivation of once-over harvest pepper cultivars might be very valuable to Korean farmers who still depend on traditional hand-harvesting method. Thus, we conducted this experiment to obtain important information for enhancing the productivity of once-over harvest red pepper fruits by supplying several nutrient-controlling and growth-regulating chemicals, such as KH 2 PO 4 , SiO 2 , and 2-chloroethylphosphonic acid (ethephon). Adequate fertilization was provided in each treatment plots. In this study, two once-over harvest pepper cultivars, Saengryeg No. 211 and 213 (SR 211 and SR 213), and one regular piecemeal harvest pepper cultivar, Kangryegdaetong (KRDT), were cultivated to evaluate the productivity of pepper fruit as affected by above chemicals. The distribution of macro- and micro-nutrients in pepper fruits among the cultivars were different in term of N, B, Cu, and Fe concentrations. In particular, the concentration of B in SR 213 was about 2 times higher than that in SR 211 and KRDT. However, overall red pepper productivity of SR 211 was markedly higher (2.91~3.38 Mg ha -1 ) than that (1.68~2.37 Mg ha -1 ) of SR 213. Also, the productivity of matured red pepper was significantly influenced by the treatments of KH 2 PO 4 , SiO 2 , and ethephon. The yield indices for matured red pepper fruits were the highest with the treatment of KH 2 PO 4 or SiO 2 with ethephon, which were 113~116% for SR 211 and 147~150% for SR 213. Thus, the applications of KH 2 PO 4 or SiO 2 with ethephon would be suggested to enhance the productivity of matured red pepper fruit.

Response of Microbial Distribution to Soil Properties of Orchard Fields in Jeonbuk Area

This study was conducted to investigate impacts of soil properties on microbial distribution in Jeonbuk orchard fields. Soil samples were collected from 110 sites cultivated with different fruit plants. The population of aerobic bacteria and fungi and the content of soil microbial biomass carbon (C) were found to increase with increasing silt content in the soils. Different activity of dehydrogenase was not observed among the different textures of soil. Microbial distribution, amount of microbial biomass C, and dehydrogenase activity in the soils were not significantly different among the topographic sites. However, in pear and grape fruit plant fields, coliform group of bacteria was found in relatively higher population, 133.0x10 3 CFU g -1 and 107.4x10 3 CFU g -1 , respectively. Microbial groups were simplified and their density was reduced with increasing the cultivation periods of fruit plants. The soil microbial distribution was proportionally correlated with some of soil properties such as soil pH, soil organic matter (SOM) content, and exchangeable Mg content; in particular, the population of Bacillus sp. was proportionally correlated with soil pH and exchangeable Mg content. The amounts of microbial biomass C and the dehydrogenase activity in the soils were significantly correlated with the contents of SOM and exchangeable Ca ion (p<0.01).

Impacts of Organic Farming System on the Soil Microbial Ecology in No-till Paddy

The seasonal changes were evaluated in the soil microbial populations by selected media in an organic farming system (OFS) with no-till management compared to those in a conventional farming system (CFS) with tillage and synthetic amendments in a flooded paddy from 2009 to 2010. The populations of aerobic bacteria and fungi in the OFS were significantly higher than those in the CFS at the harvesting stages, whereas those of Gram-negative bacteria was significantly higher in the OFS than in the CFS before the submerging stages. In addition, populations of aerobic bacteria, Gram-negative bacteria, and fungi tended to rapidly decreased after the submerging stages may be due to insufficient oxygen. Gram-negative bacteria should be considered as potential factor responsible for the microbial population differentiation observed between the OFS and the CFS in flooded paddy fields.

Assessment of Water Quality and Pollutant Loads on Agricultural Watershed in Jeonbuk Province

This study was conducted to evaluate water quality and pollutant loads on small agricultural watershed in Jeonbuk province. The EC level of investigated watershed ranged from 0.07 to 0.52 dS/m, BOD level ranged from 0.1 to 5.0 mg/L, and level ranged from 0.6 to 17.7 mg/L. As above, contents of water quality indicators covered wide range, but each indicator was alike in mean content every other year. The contents of EC, were decreased in rainy season, but the contents of BOD, , T-N and T-P were not greatly different as compared to dry season. And high content of SS showed substantial sediments near the surface flow out and influence on water system in rainy season. The pollutant loads measured in terminal of watershed were kg/day for BOD, kg/day for T-N and kg/day for T-P. The pollutant loads of BOD, T-N and T-P in rainy season increased several times as compared to dry season. In rainy season, watershed with more than 30% in the proportion of paddy field to land showed relatively low discharge and pollutant loads in comparison to watershed with less than 30%. The discharge of watershed in rainy season increased 5.7times compared with the dry season in watershed with less than 30% in the proportion of paddy field to land, whereas was only 2.3times in watershed with more than 30%. The correlation coefficient() of regression between discharge and pollutant loads of T-N were higher than those of BOD and T-P.

Effects of Expeller Cake Fertilizer on Soil Properties and Tah Tasai Chinese Cabbage Yield in Organic Greenhouse Farm

BACKGROUND: To evaluate the application level of expeller cake fertilizer(ECF), we have investigated soil chemical properties, leaf mineral contents and yield of tah tasai Chinese cabbage in a plastic film greenhouse. METHODS AND RESULTS: Five levels of fertilizer were applied as 0%(ECF 0), 50%(ECF 50), 75%(ECF 75), 100% (ECF 100) and 150%(ECF 150) by base 1,848 kg/ha of ECF. In 2012, tah tasai Chinese cabbage was planted on April 28 in a silt loam soil and harvested on July 12. Commercial yields were measured 10 times from May 10 to July 12. Electrical conductivity (2.24~3.09 dS/m), available (484~581 mg/kg) and exchangeable cations(, and ) were tended to increase by the application of ECF. However, the range of those was not significant. The contents of T-N, K, Ca and P of tah tasai Chinese cabbage leaves were 62.2~66.5 g/kg, 44.3~48.7 g/kg, 5.1~5.9 g/kg and 5.6~6.2 g/kg, respectively. The nitrogen utilization rate of tah tasai Chinese cabbage was 39.4~51.6%, and it was decreased with increased application amount of ECF. The yield of tah tasai Chinese cabbage was 9,806 to 12,730 kg/ha on the basis of application amount of ECF and it was not increased in spite of increased ECF. CONCLUSION: The optimum dose of application of ECF for cultivation of tah tasai Chinese cabbage was ranged from 924 kg/ha(as ECF 50) to 1,386 kg/ha(as ECF 75). Environment-friendly and economical amount of applied fertilizer is more important than yield for cultivation of tah tasai Chinese cabbage.

Effect of Expeller Cake Fertilizer Application on Soil Properties and Red Mustard (Brassica Juncea L.) Yield in Soil of Organic Farm of Plastic Film Greenhouse

To evaluate the application level of expeller cake fertilizer (ECF), we have investigated soil chemical properties, leaf mineral contents and yield of red mustard in plastic film greenhouse. Four levels of fertilizer were applied as 50% (ECF 50), 75% (ECF 75), 100% (ECF 100) and 150% (ECF 150) by base of ECF. In 2010, red mustard was planted on April 28 in silt loam soil and harvested on July 7. Commerical yields were measured 12 times from May 14 to July 7. Electrical conductivity (), available () and exchangeable cations (, and ) were tended to increase by the application of ECF. However, the range of those was not so big increasing amount. The content of T-N, K, Ca and P of red mustard leaves was , , and , respectively. The nitrogen utilization rate of red mustard was 38~52%, and it was decreased with increased application of ECF. The yield of red mustard was 13,670 to on the basis of application amount of ECF and the yield did not increased in spite of increased ECF. The optimum dose of application of ECF for cultivation of red mustard was from (ECF 50) to (ECF 75). Environment-friendly and economical amount of applied fertilizer is more important than yield for cultivation of red mustard.

Management of Recycled Nutrient Resources using Livestock Waste in Large-Scale Environment-Friendly Agricultural Complex

This experiment was carried out to investigate soil properties and the requirement of livestock manure compost in a large-scale environment-friendly agricultural complex (EFAC), Gosan, Wanju-gun, Jeonbuk. Total cultivation area of major crops was 2,353 ha. This complex area included different types of environment-friendly cropping sections (402.9ha) and livestock farming including 21,077 Korean beef cattle, 1,099 dairy cow, and 32,993 hog. Amount of livestock waste carried in to Resource Center for Crop and Livestock Farming (RCCLF) was 32 Mg per day and the production of manure compost was 9,600 Mg per year. The manure contained 1.4% total nitrogen (T-N), 2.7% phosphorus as , 2.1% potassium as , 0.9% magnesium as MgO, 2.5% calcium as CaO. Amount of compost used in the EFAC was 6,588 Mg per year. Soil pH values in the EFAC were varied as follows: 78.1% of paddy field soil, 58.2% of upland soil, 60.3% of orchard field soil, and 62.1% of greenhouse soil were in proper range. For the content of soil organic matter, 41.7% of paddy field soil, 46.5% of upland soil, 40.5% of orchard field soil, and 81.4% of greenhouse soil were higher than proper range. The content of available phosphorus was mostly higher than proper value on the different fields except upland soil. The contents of exchangeable , , and were also exceeded in the orchard field and greenhouse soils. In addition, microbial population, especially aerobic bacteria, in the EFAC was higher than that in regular farming land.