• Korean Journal of Weed Science
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• v.13 no.1
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• pp.1-6
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• 1993

The experiments were conducted in order to find out the response of algae as affected by fertilizer and salinity, and to determine the chemical control method of algae in 1991. The higher the nitrogen fertilizer level, the more the occurrence of a blue-green alga Oscillatoria concerning with soil flakes. An increase in phosphorus fertilizer level stimulated the growth of green alga Hydrodictyon, whereas an increase in nitrogen level caused its abrupt reduction due to the harmful effect at high concentration of nitrogen, The high level of nitrogen fertilizer also reduced the growth of Euglena, although the detrimental effect was less compared with that of Hydrodictyon. A blue-green alga Oscillatoria, a green alga Cladophora and a diatom Navicula were tolerant to salinity. Piperophos/dimethametryn was highly effective in controlling various algae such as a green alga Hydrodictyon, suspended unicellular green algae and Euglena species. A fungicide propineb and copper sulfate also effectively controlled Hydrodictyon.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.2
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• pp.119-125
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• 1974

Uptake amount, percent translocation to grain and grain yield efficiency of N. P. K. Si were investigated with N. P. K simple trials (countrywide, 1967~69) and other nitrogen fertiltzer field trials in relation to yield class. 1) Uptake rate with yield increase were similar in all nutrients but silica showed greater yearly variation. 2) In N. P. K simple trials showing very low nitrogen efficiency(46kg grain/ nitrogen uptake kg) it and percent translocation increased with yield increase. 3) Nitrogen efficiency deacreased with the increase of nitrogen uptake and the decreasing rate depends greatly on fertilizer forms and variety. Nitrogen efficiency was greater in sandy loam where yield was higher than in clay loam. 4) Nitrogen efficiency positively correlated with percent translocation. 5) In high yielding fields yield was attributed only to the increase of nitrogen uptake, keeping efficiency around 50. 6) Major factor for high yield is considered as the increase of nitrogen efficiency rather than nitrogen uptake. 7) Phosphorus efficiency in N. P. K. simple trials was considerably low, suggesting too much uptake due to soil reduction.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.4
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• pp.199-217
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• 1975

For the establishment of efficient method of potassium topdressing on rice the optimum time and amount were investigated and discussed on the basis of available data from nutriophysiological studies, soil characteristics and fertilizer trials in fields. The followings were pointed out. 1. According to yield rice plants require more potassium around heading under water culture. 2. Potassium involves in harvest index, filled grain ratio, grain weight and number of spikelets per panicle. 3. Potassium is lost after heading in most fields in spite of highest requirement during this period. 4. The higher $K_2O/N$ ratio in straw at harvest is, the higher the yield. 5. Relatively low efficiency of potassium fertilizer under the field condition may be due to improper application method rather than natural supply from soil and irrigation water. 6. Appropriate topdressing time appears at in effective tillering stage for the prevention of nitrogen excess and at 15 to 20 days after transplanting, ear formation stage and 5 days after heading for the prevention of soil reduction damage. Two times of topdressing for clayey soil and three times for sandy soil seems reasonable in practice together with nitrogen topdressing, 7. The reasonable ratio basal to topdressing of potassium fertlizer seems to be 2/3 and $N/K_2O$ ratio of fertilization for ear formation stage appeared also as 2/3.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.3
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• pp.134-141
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• 2005

Cultivation of winter cover crops and its soil utilization for summer main crops in slope upland is very important at the respects of diminution of soil erosion and non-point pollution source. The effects of cover crop, hairy vetch as no-tillage or conventional tillage on prevention of soil erosion and reduction of chemical nitrogen fertilization were investigated in the slope upland with whiter clover living mulch (partial tillage) in Suwon for three years and with rye (conventional tillage) in Hongcheon for two years, respectively. In Suwon, amounts of soil lost by rainfall runoff decreased as much as 90% by hairy vetch-no tillage (HV-NT), white clover-partial tillage (WF-PT) together with the decrease of rainfall runoff compared to winter fallow with conventional tillage (WF-CT). In addition, amounts of weed also decreased as much as 80-90% by HV-NT and WF-PT. Corn yield decreased much at the plot of WF-PT mainly due to competition for soil water and nutrients between clover and corn at the early corn growth stage. On the contrary, corn yield increased by HV-NT compared to WF-CT regardless of weed control. In Hongcheon, amounts of soil eroded during winter season before corn seeding were reduced as much as 95% by cultivation of hairy vetch and rye compared to winter fallow. Amount of soil eroded during waxy corn growing season was reduced as much as 98% by HV-NT compared to WF-CT. Also, soil incorporation of hairy vetch and rye as green manure with conventional tillage at corn seeding time could reduce soil erosion as much as 70% compared to no soil cover with conventional tillage. Ear yields of waxy corn were increased 10% higher at hairy vetch green manure (HV-CT) without nitrogen fertilizer, 20% higher at HV-NT with standard nitrogen fertilizer, respectively than WF-CT. But ear yields of waxy corn were decreased by rye green manure (R-CT) and HV-NT at the condition of no nitrogen fertilizer. It was concluded that hairy vetch was better as winter cover crop to reduce both soil erosion and chemical nitrogen fertilizer simultaneously in slope upland than other cover crops.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.97-101
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• 1999

No-till direct seeding cultivation of rice has major advantages such as saving of labor and cost by eliminating tillage, preparation of seed bed and trans-planting procedure compared to the conventional transplanting cultivation. A field experiment was conducted to evaluate the effects of straw treatment and nitrogen levels on the rice growth in no-till direct-seeding cultivation. Rice straw, vetch straw, and the mixture of both of the straws were mulched on the surface of soil before seeding while 4 levels of nitrogen fertilizer, 0, 7, 9, and 11 kkg/10a respectively, were applied at 3 split times, 3-weeks after sowing, 5-weeks after sowing and the panicle initiation stage. Mulching of vetch straw significantly reduced seedling establishment of rice which may be attributed to low oxidation-reduction potential of soil by vetch mulching treatment. Vetch straw increased the concentration of soil ammonium leading to an extension of the greenish leaf to panicle initiation stage. Agronomic nitrogen use efficiency (AD $E_{N}$) in heavy-mixed straw mulching plots was lower than other treatments. Grain yield and AU $E_{N}$ in the vetch treatment were less affected by fertilized N levels. Conclusively, it is suggested that heavy straw mulching was not efficient for rice seedling establishment and nitrogen usage.e.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.5
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• pp.381-387
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• 2003

Winter hairy vetch (HV) can be used as green manure with conventional tillage system (CT), in which chemical N fertilizer required for cultivation of sub-sequent com could be fully saved, or as cover crop with no-tillage system (NT) in which soil could be protected from erosion, control of weed, and the reduction of N fertilizer application. This experiment was carried out to compare the enrichment of soil mineral nitrogen (SMN) at corn root zone, and the changes of com growth and N uptake according to HV amounts (winter fallow, above-ground HV removed, intact HV, and HV added from aboveground HV removed) under two tillage systems in the upland field of National Crop Experiment Station, Suwon, Korea in 1996. HV cultivation during winter decreased SMN a little at com planting. HV incorporation with CT increased SMN rapidly during early growth stage according to rapid decomposition of Hv. SMN by HV cover with NT was increased slowly and its increase was higher in the surface soil (soil layer 0-7.5cm) compared to deep soil layer 7.5-22cm. Com growth and N status at corn silking stage, com yield and N uptake at harvest were increased in proportion to aboveground HV amounts regardless of tillage system. Average hairy vetch nitrogen (HV-N) uptake efficiency by com was 10% higher with CT than with NT in which average HV-N uptake efficiency was 43 %. Corn yields were not different between two tillage systems, but corn N uptake was increased by 33 kgN/ha more with CT than with NT due to the increase of corn N concentration. The increase of SMN and com N uptake from HV cover with NT could not be disregarded though those with CT were higher than with NT

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.95-101
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• 2006

This study was conducted to establish a low-input fertilization technique and increase of fertilization efficiency using the band spotty applicator(1999-2000) during the cultivation of mulching for chinese cabbage(Brassia campestris L.). The obtained results such as nitrogen efficiency, yield and soil improvement after cultivation of chinese cabbage were as follows. The content of $NO_3-N$ in soil increased in band spotty fertilization(BSF) by increasing application rate from the beginning stage to the middle stage. The content of total nitrogen increased but content of organic matter, available phosphate and exchangeable potassium decreased in comparison with the soil before experiment. Growth rate of Chinese cabbage increased in band spotty fertilization plot and uptake amount of nitrogen fertilized for chinese cabbage increased by increasing of the application rate. N use efficiency was higher by 5-21% in band spotty fertilization plot than in conventional fertilization(CF) plot. Yield of chinese cabbage increased by 16% in 70% band spotty fertilization plot and increased by 20% in 100% band spotty fertilization plot. It was found that 70% band spotty fertilization was more effective as fertilization method to reduce both environmental pollution and chemical nitrogen fertilizer in plastic film mulching cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.35-41
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• 1987

Nitrate nitrogen was absorbed dominantly among the inorganic nitrogen nutrients by tobacco plant. Transport and reduction of $NO_3-N$ in plant tissue were the important metabolism for supplying synthetic N compounds to developing tissues during growth period. Under field and environment-controlled condition tobacco plants were grown and seperated to leaf tissues at stalk positions for investigation of nitrogen transport and assimilation ability during period of rapid vegative growth. The results of studies were summarized as follows: 1. $NO_3-N$ absorbed from roots was transported as inorganic nitrogen through the vascular tissue of leaf veins as resulting from the high $NO_3-N$ ratio of the nitrogen content in leaf veins, but these ratios in mesophyll tissue of the same leaf laminae decreased remarkably in disregard of higher accumulation of nitrogen being compared to midvien. 2. Mesophyll tissue of mature leaves appeared higher value of nitrate reductase activity (NRA) comparing with other tissues, stem, leaf vien, and meristmatic tissue at emergence point with young leaves. 3. Matured leaves at lower position being reducing nitrate nitrogen vigorously observed thick laminae and kept high amount of water in them. 4. Mature leaves of young plant reduced $NO_3-N$ vigorously for supply synthetic N compounds to meristmatic tissues at growing point by the reason of narrow and few leaves at young stage, but in advancing growth period NRA of mature leaves along upper position reached to lower value. This appearence attributed to distribution of organic-N compound demanding for growth to increasing numbers of wide leaves.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.368-373
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• 2014

Ammonia loss from urea significantly hinders efficient use of urea in agriculture. The level of nitrous oxide ($N_2O$) a long-lived greenhouse gas in atmosphere has increased mainly due to anthropogenic source, especially application of nitrogen fertilizers. There are reports in the literature showing that the addition of zeolite to N sources can improve the nitrogen use efficiency. This study was conducted to evaluate nitrous oxide ($N_2O$) and ammonia ($NH_3$) emission by mixed treatment of urea and zeolite in upland crop field. Urea fertilizer and zeolite were applied at different rates to study their effect on $N_2O$ emission during red pepper cultivation in upland soils. The $N_2O$ gas was collected by static closed chamber method and measured by gas chromatography. Ammonia concentration was analyzed by closed-dynamic air flow system method. The total $N_2O$ flux increased in proportion to the level of N application. Emission of $N_2O$ from the field increased from the plots applied with urea-zeolite mixture compared to urea alone. But urea-zeolite mixture treatment reduced about 30% of $NH_3$-N volatilization amounts. These results showed that the application of urea and zeolite mixture had a positive influence on reduction of $NH_3$ volatilization, but led to the increase in $N_2O$ emission in upland soils.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.306-314
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• 2021

The application of organic fertilizer could be accompanied by potential hazards to soil and humans due to trace metals. Livestock manure compost·liquefied fertilizer is a well-established approach for the stabilization of nutrients and the reduction of pathogens and odors in manures, which can be evaluated as compost·liquefied. In this study, the livestock manure compost·liquefied fertilizers produced at 333 liquid manure public resource centers and liquid fertilizer distribution centers were collected from May to December 2019. The nutrient content (nitrogen, phosphorus, and potassium), physicochemical properties, and heavy metal content were investigated. The livestock manure compost·liquefied fertilizer was measured using a mechanical maturity measurement device. The organic matter, arsenic, cadmium, mercury, lead, chromium, copper, nickel, zinc, E. coli (O157:H7), Salmonella, etc. of the livestock manure compost·liquefied fertilizers were analyzed. The average heavy metal content in the livestock manure compost·liquefied fertilizer was as follows: Cr 2.9 mg/kg (0.2~8.7 mg/kg), Cu 20.4 mg/kg (1.6~74.1 mg/kg), Ni 1.3 mg/kg (0.4~4.2 mg/kg), and Zn 79.8 mg/kg (3.0~340.7 mg/kg). Although large-scale organic fertilizer plants and resources recycling centers produce good organic (liquid) fertilizers with proper components, it is necessary to standardize livestock manure compost·liquefied fertilizer in order to facilitate efforts to turn livestock manure into useful resources.