• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.3
• /
• pp.255-263
• /
• 1996

This study was conducted to evaluate the application effects of three different granular fused magnesium phosphate products on soybean in a volcanic ash upland soil(Namweon series) of Cheju island. They were two domestic products(Kyunggi Chemical Industrial Co., LTD, Pungnong Biryo Industrial Co., LTD) and an imported Chinese product that were manufactured from different added materials. A powder fused magnesium phosphate. a single superphosphate(water soluble phosphatic fertilizer) and a fused superphosphate(mixed water soluble phosphate and 2% citric acid soluble phosphate) were presented as check fertilizers. Yield of soybean was the highest in the Pungnong product of granular fused magnesium phosphate. the next was the Chinese product imported and the Kyunggi product was the lowest but there was no statistical significance among the three granular products of fused magnesium phosphate. There was no clear tendency between yield and yield components of soybean plant however, the effects on the number of mainstem nodes, number of branches nodes and number of pods per plant were observed in the increased yield treaments. Phosphate concentration in stems and pods of soybean plant at harvesting stage was higher than those in stems of soybean plant during growing period. Uptake amounts and recovery rates of phosphate in stems and pods of soybean plant at harvesting stage were similar with the yield increasing tendency on soybean. In the changes of soil pH at different periods, the application of phosphatic fertilizers was increased soil pH. Soil pH in Chinese product was higher than domestic products, but it was similar to single superphosphate. The available silicate concentrations of soil were higher in the plot of Pungnong product than Chinese product.

• Korean Journal of Organic Agriculture
• /
• v.15 no.2
• /
• pp.207-218
• /
• 2007

Coming with the well-being era, consumer's demand for safe agricultural products is increasing. So, it is urgent to develop an environment-friendly rice production system. Accordingly, this study was conducted to develop an environment-friendly rice production system by using Amo known as EM(effective microorganisms) and also known as being effective in environment-friendly rice production with several other environment-friendly agricultural materials. The highest number of tillers per hill was obtained from level 2 of EM treatment (48.8 tillers per hill), while the lowest was obtained from the control plot (41.0 tillers per hill). Leaf area per hill at heading stage was the highest in level 3 of EM treatment $(3228.5cm^2)$, while control was the lowest leaf area $(2264.7cm^2)$, which is 70.2% compared to the level 3 of EM treatment. The highest effective tillers was obtained from the control (63.7%), while the lowest effective tillers was obtained from the level 3 of EM treatment (55.4%), which were treated with higher amounts of environment-friendly agricultural materials. Level 3 of EM treatment showed the highest number of panicles per hill (20.9), while the control showed the lowest number of panicles per hill (19.3). In the spikelets per panicle, level 2 of EM treatment showed the highest number of spikelets (85.2), while the control showed the lowest number of spikelets (81.9) and there was a statistically significant difference among the three levels and control. The highest grain filling ratio was obtained from the control (85.0%), while level 3 of EM treatment was the lowest grain filling ratio and there were no great difference between treatment levels. Regarding the 1000 grain weight, the control showed the highest 1000 grain weight (21.7g), which is heavier by about 1g compared to treatment levels. Level 2 of EM treatment showed the highest rough rice yield per 10a, while level 3 of EM treatment was the lowest and they also showed a statistically significant difference among treatment levels.

• The Journal of Engineering Geology
• /
• v.25 no.4
• /
• pp.533-545
• /
• 2015

Spatial and seasonal variations in hydrogeochemical characteristics and the factors affecting the deterioration in quality of shallow portable groundwater in an agricultural area are examined. The aquifer consists of (from the surface to depth) agricultural soil, weathered soil, weathered rock, and bedrock. The geochemical signatures of the shallow groundwater are mostly affected by the NO₃⁻ and Cl⁻ contaminants that show a gradual downward increase in concentration from the upper area, due to the irregular distribution of contamination sources. The concentrations of the major cations do not varied with the elapsed time and the NO₃⁻ and Cl⁻ ions, when compared with concentrations in background groundwater, increase gradually with the distance from the upper area. This result suggests that the water quality in shallow groundwater deteriorates due to contaminant sources at the surface. The contaminations of the major contaminants in groundwater show a positive linear relationship with electrical conductivity, indicating the deterioration in water quality is related to the effects of the contaminants. The relationships between contaminant concentrations, as inferred from the ternary plots, show the contaminant concentrations in organic fertilizer are positively related to concentrations of NO₃⁻, Cl⁻, and SO₄²⁻ ions in the shallow portable groundwaters, which means the fertilizer is the main contaminant source. The results also show that the deterioration in shallow groundwater quality is caused mainly by NO₃⁻ and Cl⁻ derived from organic fertilizer with additional SO₄²⁻ contaminant from livestock wastes. Even though the concentrations of the contaminants within the shallow groundwaters and the contaminant sources are largely variable, it is useful to consider the ratio of contaminant concentrations and the relationship between contaminants in groundwater samples and in the contaminant source when analyzing deterioration in water quality.

• Korean Journal of Soil Science and Fertilizer
• /
• v.20 no.2
• /
• pp.185-192
• /
• 1987

A green house experiment was conducted to find out the acetylene reducing and $N_2$-fixing activity from photosynthetic and aerobic heterotrophic nitrogen fixing microorganisms in submerged paddy soil under different agricultural locality, soil series, soil texture, soil type, and drainage condition in which samples taken from without nitrogen treatment plot of NPK trials on 16 sites of the farmer's field. The results obtained were summarized as follows: 1. The highest acetylene reducing activity was observed at 7 days after incubation in the light condition (photo synthetic microbes+heterotrophic bacteria) while it was observed at 35 days incubation in the dark condition (heterotrophic bacteria). 2. Among the soil series, photosynthetic nitrogen fixing activity was pronounced more in Jangae, Ogcheon and Hwadong series while lower was obtained in Buyong and Daejeong series. Aerobic heterotrophic nitrogen fixing activity was high in Buyong and Daejong series. 3. Estimated amount of $N_2$-fixation from acetylene reducing activity was equivalented to 3.0 mg in light condition and 4.9 mg/100g/105 days in dark condition. 4. Among the agricultural locality, photosynthetic nitrogen fixing activity was high in rather warm southern part while heterotrophic nitrogen fixing activity was predominated more in mountainous area and Chungcheong continental. 5. Photosynthetic nitrogen fixing activity was predominated in high productive soil while aerobic heterotrophic nitrogen fixing activity was pronounced more in crose coarse sandy soil. 6. The soils properties of high photosynthetic nitrogen fixing activity were constituted of poorly or imperfectly drained clay or clay loam soil while heterotrophic nitrogen fixing activity was pronounced more in well to moderately well drained sandy or sandy loam soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.6
• /
• pp.372-379
• /
• 2006

This study was carried out to improve chemical properties of salt-accumulated plastic film house soil. Compressed expansion rice hull was applied at 0, 2.5, 5.0, $7.5Mg\;ha^{-1}$, and drip irrigation was initiated at -33 kilopascals (kPa) of soil water potential and ceased adjusted up to -10 kPa. Another treatment was the application of inflated rice hull at $5.0Mg\;ha^{-1}$ with drip irrigation starting at soil water potential -20 kPa and adjusted to -10 kPa. Lettuce(Lactuca sativa L.) was cultivated at sandy loam soil with $5.1dS\;m^{-1}$ of electrical conductivity (EC). $EC_w$(1:5) of plots treated with $5.0Mg\;ha^{-1}$ of inflated rice hull and irrigated at the point of -20 kPa and -33 kPa of soil water potential was reduced by 26% and 24% less than untreated control plot, respectively. Soil $EC_w$(1:5) has close relationship with $Cl^-$ as well as $NO_3{^-}-N$ and $SO{_4}^{2-}$ in the soil. Total nitrogen in leaf of lettuce was deficient in the earlier growth stage. The yield of lettuce increased by 6% by the application of inflated rice hull of $5.0Mg\;ha^{-1}$ with drip irrigation starting at -33 kPa of soil water potential. It decreased 4% when the drip irrigation was stated at -20 kPa of soil water potential. The amount of water used for irrigation was reduced with the increasing application of inflated rice hull. The watering initiated at the point of -33 kPa was more economical compared with starting at -20 kPa.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.5
• /
• pp.808-813
• /
• 2011

This study was conducted to reduce the dependability of farmers on chemical fertilizers for rice cultivation. Soil chemical and biological properties were monitored before experiment and at the time of harvesting. The results showed that EC, available $SiO_2$, and exchangeable $Ca^{2+}$ were decreased at the time of harvesting while pH, OM, and exchangeable $K^+$ and $Mg^{2+}$ were remain unchanged, compared with soil before experiment. Population of aerobic bacteria, Bacillus sp., and fungi were also increased at the time of harvesting in the paddy field, compared with before fertilization, in the treatment of 50% soil-testing fertilizer+ 50% compost. Concentrations of N, P, and K in rice leaves increased with the fertilizers application, maximum increase was recorded in 50% soil-testing fertilizer+ 50% compost. Non-significant difference was observed in the morphological parameters of rice among the treatments. The chlorophyll contents of rice leaf increased in a similar fashion up to 60 days, thereafter, sharp decrease was observed in all the treatments. Maximum yield (per 10a) was recorded in the field treated with 50% soil-testing fertilizer+ 50% compost followed by standard applied fertilizer, 70% soil-testing fertilizer+ 30% compost, soil-testing fertilizer and unfertilized plot. Amylose content showed non-significant difference within the treatments. Protein content increased with the use of fertilizers and best protein content was recorded in the treatment of 50% soil-testing fertilizer+ 50% compost. It was concluded that the amount of the chemical fertilizer used was directly proportional to the protein content of rice grain. However, the palatability of rice grown in unfertilized field was better than the treatments but minimum yield was obtained. Hence, the treatment of 50% soil-testing fertilizer+ 50% compost, was the best among the fertilizer combinations for rice cultivation as supported by the yield, protein and palatability index.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.3
• /
• pp.457-464
• /
• 2011

Livestock manure compost (LC) generally contains high content of phosphorus, therefore can be a substitute for phosphorus fertilizers. In this experiment of the cultivation of lettuce in green house, the possibility of LC as a subsitute for phosphorus fertilizer was investigated and the fertilizer efficiency of nitrogen and potassium in LC as compared with chemical N fertilizer (urea) and K fertilizer (potassium chloride) was examined. In proportion to the increase in the application rate of nitrogen fertilizer, soil pH declined, whereas EC and $NO_3$-N content became higher. The application of LC appeared to increase the soil content of organic matter, available phosphate, exchangeable calcium, magnesium and sodium more than that of chemical fertilizer. Supplementation of the K fertilizer by the lack amount from the application of LC resulted in the same exchangeable potassium content in soil with NPK plot in which N, P and K fertilizers were applied by the amount of soil test recommendation. The relationship between soil $NO_3$-N content and nitrogen application rate from fertilizer and compost showed as y=0.57717a+0.19760b+74.65 ($R^2$=0.6347) in which y is the soil $NO_3$-N content (mg $kg^{-1}$), a is nitrogen application rate from fertilizer and b is nitrogen application rate from compost (kg $ha^{-1}$), respectively. From this equation, the supply ability of $NO_3$-N into soil of LC exhibited about 34% (pig manure compost 37.0, chicken manure compost 34.7, cattle manure compost 23.3) of nitrogen fertilizer (urea).

• Korean Journal of Agricultural Science
• /
• v.13 no.1
• /
• pp.103-112
• /
• 1986

This study was carried out to prevent the entwining of rice straw on rotary shaft and blade where rice straw was spreaded on paddy field as an organic source before rotary tilling. The rotary tillage was conducted in the paddy field having the soil moisture contents of 30%, 39%, 59% in dry basis and spreaded rice straw (450kg/10a) of 30cm, 45cm, 90cm length with the edged curve angles of rotary blade of $30^{\circ}$, $40^{\circ}$, $50^{\circ}$, $55^{\circ}$ at Yuseung area. And the test were performed on the plot which has width of 30cm and 5cm length and the quantity of entwined rice straw was analized. The test results were summarized as the followings. 1. Entwining phenomenon of rice straw was decreased as the blade edged curve angle increased. The edged curve angle of rotary blade must be determind by considering the characteristics of soil cutting resistance, tilling torque and entwining phenomenon of rice straw. But according to the entwining phenomenon of rice straw only, the edged curve angle of rotary blade should be bigger than $55^{\circ}$ for design. 2. Amount of entwining rice straw was minimized when soil moisture contents was 30 percent (d. b.). It would be better that rotary tillage is performed when soil moisture contents is lower than 30 percent in dry basis. 3. Amount of entwining rice straw was minimized when the length of rice straw was 30cm with $55^{\circ}$ edged curve angle. Therefore, it would be better to chop rice straw as 30cm. 4. Entwining phenomenon of rice straw was decreased as the forward speed decreased. To decrease the entwining rice straw, rotary tillage should be done with forward fist gear (0.35m/s).

• Korean journal of applied entomology
• /
• v.46 no.1 s.145
• /
• pp.109-115
• /
• 2007

This study was carried out to determine occurrence and damage of golden apple snail, Pomacea canaliculata on water seeding area in Jeonnam province. The density of golden apple snail maintained hlgh until October 2003, but quickly decreased from November. They overwintered only in a portion of the water canals but could not find in dried paddy field. They reproduced from May and June in the canal water and paddy field, respectively. Feeding time of golden apple snail on rice seedlings was 235.2 seconds, feeding length of that was 8.4cm. When golden apple snail fed rice seedlings, the stem remain only 2.5cm from areal part which could not recover. The more density of golden apple snail, the fester feeding rate. Density and number of eggs laid of golden apple snail after overwintering was higher on bank around of paddy field than on middle of that. The percent of shell size after over wintering was higher in small (below 25mm) than big (over 36mm). But in case of Boseong area, the slze was reverse because the soil has soft mud. The survival rate of overwintering golden apple snail was lower than that of breeding. They did not move when the temperature changed rapidly, but the temperature increased they start to move. They dead almost below $-3^{\circ}C$. The damage of rice by golden apple snail in the direct water seeding was 20%. In machine transplanting, rice damaged only fore-end of leaf and recovered subsequently. When golden apple snail release in direct water seeding field, the percent of damage was 5.6% in immediately release plot. The later release, the lower damage.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.3
• /
• pp.201-205
• /
• 2000

Eleven runoff $plots(3{\times}15\;m)$ were built on a sloping field of a high plateau in Kangwon Province, Korea. The plots were treated with different tillage, residue covers and fertilizers, corn and potato were cultivated, and sediment discharge was measured from the plots for 3 years. Agricultural management practices were monitored around the plots to develop adequate best management practices. The least sediment occurred from the plots with no-till and 100% residue cover $(corn,\;0.1{\sim}2.2\;t/ha/year)$ and with contour tillage and vinyl sheet cover plots $(potato,\;0.1{\sim}0.2\;t/ha/year)$. The largest sediment was measured from the plots with up-and-down till and no cover ($11{\sim}33$ and $16{\sim}31\;t/ha/year$ from corn and potato plots, respectively). The type of organic and commercial fertilizers seemed not to affect sediment discharge. Sediment discharge from contour plots were largely dependent on the collapse of ridges due to the flush of water stored in furrows. The sediment discharge from contour corn and potato plots with no residue cover was $10{\sim}27$ and $16{\sim}24\;t/ha/year$, respectively. No-till with residue cover, vinyl cover for tuber crops, construction of furrow dam, frost heave research, furrow and ridge tillage with furrow dam after tuber crop harvest, limited stalk harvest of row crops, use of winter cover crops, and other common best management practices were recommended to minimize the sediment discharge from a high plateau sloping land culture.