• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.276-282
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• 1982

To estimate the responses of sesame plant in growth and yielding traits to different soil drainage conditions, a pot trial was conducted by using of sesame variety "Suweon-9" were introduced with 5 different mixing combinations of clay and sea-sand soils as 0:100, 25:75, 50:50, 75:25, and 100:0 percents in volumetric ratio. Also two irrigation methods as 20mm/6 days interval and 10mm/3 days interval were detected. As a result, water drainage was linearly decreased with increament of clay contents. And the excess drainage condition(such as pure sand soil) required more irrigation, however in crop growths, no significant differences among various soil drainage conditions except the pure sand were recognized. On the other hand, number of capsules per plant, among other yielding components, was most contributed factor to the yield, which was effectively given from the soil mixed with clay and sea-sand as 75% and 25%, respectively. Therefore, much similar responses were also detected from the seed yields per a sesame plant. However, the number of seeds per capsule and maturity function were more effectively composed under the soil mixed with clay and sea-sand as 25% and 75% respectively better than under the soil of 75% and 25%. As a conclusion, the yielding responses of sesame plant was advanced more effectively at the soil conditions of water conserved type (e.g. 25%/75% in clay/sand ratio) than of water-draining type (e.g. 75%/25% in clay/sand ratio).nd ratio).

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.73-85
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• 2009

An investigation was conducted to get the basic data for establishing structural safety and environmental management of tomato greenhouses in Chungnam region. The contents of the investigation consisted of actual state of greenhouse structures and environmental control facilities. Most of greenhouses were arch type single-span plastic houses and they had too low height for growing tomatoes. Frameworks of multi-span greenhouses were suitable, but those of single-span were mostly insufficient. Every greenhouse had thermal curtain movable or covering fixed inside the greenhouse for energy saving, and heating facilities were mostly warm air heater. Irrigation facilities were mostly drip tube and controlled by manual operation or timer. Almost all of the greenhouses didn't install high level of environmental control facilities such as ventilator, air circulation fan, $CO_2$ fertilizer, insect screen, supplemental light, and cooling device.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.3
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• pp.207-211
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• 1984

A series of soil surveys was conducted in 102 high yielding paddies randomly selected. Each paddy field was the contest winner's in a county, a province or the nationwide during 1976 to 1979. The data on soils and yields of the paddies were evaluated to find out the better practices. Cultivation practices such as intermittent irrigation, deep ploughing and application of soil improvement materials were intensively carried out with the increasing rates of yield. But, the yield of rice in the high yielding paddies was not significantly different according to the paddy soil type or the suitability calss. About 70% of the high yielding paddies were distributed in loam and silty clay loam. The properties of top soil in the high yielding paddies were more improved as compared with the common paddies. The cultivated soil depth and nutrient holding capacity were thought of as the important soil factors for high yield.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.77-82
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• 2007

Volatilization of ammonia from N fertilizer is the major mechanism of N losses that occur naturally in all soils and is influenced by numerous soils, environmental and N fertilizer management factors. Vegetables are often damaged by $NH_3$ gas volatilized from the high rates of N fertilizer. We determined the rate of $NH_3$ volatilization from urea applied to surface of the alluvial soil (coarse silty, mixed, mesic family of Dystric Fluventic Eutrochrepts, Ihyeon series) as affected by fertilizer management factors such as rate of urea application, irrigation schedule and temperature. The $NH_3$ volatilization was triggered about 3 d after urea application and reached at maximum level in general within 15 days. Cumulative amounts of 3.0, 4.4, and 8.0 kg of $NH_3$ N after 17 d were volatilized at application rates of 200, 400, and $600kg\;N\;ha^{-1}$, respectively, which were equivalent to the N losses of 15.0, 10.9, and 13.0% of N applied. Masses of N volatilization were 5, 21, 75 and $87kg\;NH_3\;N\;ha^{-1}$ at 5, 8, 22, and 28, respectively. Total amounts of 21.3, 21.2, and $16.6kg\;N\;ha^{-1}$ were volatilized at control, 5 and 10 mm water irrigation before fertilization, respectively. However, those at 5 mm irrigation after fertilization were only $10.44kg\;N\;ha^{-1}$. Results showed that urea loss can be avoided by incorporating with the recommended level, applying when temperatures are low or irrigating immediately to carry the urea into soil.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.159-164
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• 1991

A field microplot(D 20cm, L 85cm) experiment filled with Bonryang sandy loam soil (Typic Udifluvents) was conducted to obtain quantitative information on the movement of applied nutrients under diffetent soil moisture regimes and ladino clover cultivation. Chloride moved rapidly with soil water. When soil moisture tension was maintained at loer than 0.2 bar most of the Cl appeared to move outside the microplot 4 month after the microplot installation. Regardless of soil moisture condition, Cl was not detected in the soil due to the fast movement of the Cl beyond the microplot after 5.5 months Although large amount of P and water were applied to the soil of high available P during the field experiment, movement of P was negligible and most of P remained in thc place where applied due to the low solubility of the fused and superphosphate. Phosphate in the soil extracted by Bray No.1 solution and taken up by plant increased with soil moisture. Under the condition of irrigation at 0.2 bar, plant took up 23% of the applied P, and 24% of the P was extracted by Bray NO.1 solution, while plant took up 14% and 13% of the P was turned out to be Bray No.1 P. at thc nonirrigated condition after final harvest.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.159-167
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• 1997

To cope with the mass-production and supply of plug seedling, the supply of transplanters is necessary. In the study, a transplanting test was carried out to find the optimum working condition in the mechanizd transplantation and to acquire the basic data for the improvement of transplanters by the research and analysis of working capacity of the local manual transplanters. The size of hopper affected transplanting stand and rate. Re-irrigation was required for the transplanted seedlings because they wilt 1 day after the transplanting if soil compaction is incomplete. Consequently, back-forth-left-right compaction method was good for soil covering and compaction. It may be thought to increase the amount of irrigation water at the time of transplanting by double-irrigation mechanism, but it needs to increase the larger water tank which makes the operation uneasy. So, assuming the working model by 1 or 2 operators with the machine size as small as possible, it seemed that eliminating of automatic irrigation method was desirable in view of efficiency. Though semiautomatic transplanter needs some structural improvements, it seemed still suitable for transplanting of plug seedlings such as 45-day red pepper seedlings in 128-hole tray and 25-day Chinese cabbage seedling in 128-hole tray. If traveling speed of the transplanter is limited to less than 14 m/min, with the transplanting depth of 2~3cm and transplanting space of 30cm.

• Journal of Bio-Environment Control
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• v.9 no.1
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• pp.20-26
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• 2000

This study aims at analyzing physical and chemical properties of perlite substrate. Particles of substrate were divided into five categories In size: gravel, very-coarse, coarse, medium and fine grade. Particles of very-coarse and greater grades in perlite substrate occupied 98.5％ of total particles. The air phase of total particles was distributed between 76.8％ and 87.7％ with especially showing that of very-coarse grade was lower than that of coarse or smaller one. However, the liquid and solid phases were vice versa. The cation exchange capacity (CEC) measured was highest in the fine grade. In drainage experiments, the water being drained from the substrate increased with the ratio of drain area, and the 65~70％ of total water reduced within five minutes after irrigation. The drained volume was proportional to the depth of the substrate, which contained about 2mL.cm$^2$：by depth (cm). Due to quick reduction of the water in the substrate, the pF value increased in four minutes after irrigation and showed the highest negative correlation ($R^2$＝0.997) with the moisture content of the substrate. The physical and chemical properties including drainage characteristics analyzed in this study can be, therefore, utilized to control the moisture content of perlite substrate, efficiently.

• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.235-243
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• 2014

This research was conducted to investigate the influence of leaching fractions (LF) in each irrigation or fertigation on plant growth and changes in chemical properties of root media during the production of seedling grafts of tomato. Two root media containing Sphagnum peat moss plus vermiculite (5:5, v/v, PV) and coir dust plus vermiculite (5:5, v/v, CV) were formulated and pre-planting fertilizers were incorporated during formulation. Then, each medium was packed into 50 cell (volume 33 cc) and 105 cell (volume 18 cc) trays and the rootstock (cv. J3B Strong) and scion (cv. Sunmyung) were grown, respectively. The seedlings were grafted at 31 days after sowing and then the cut seedling grafts (Sunmyung scion/J3B Strong rootstock) were planted into 50 cell plug trays containing each of the two root media. After induction of the graft union and new adventitious roots for 7 days, the seedling grafts were fed with fertilizer solution once a week containing 4 different N concentrations (0, 50, 100, $200mg{\cdot}L^{-1}$). When determined after 31 days from seed sowing, the highest fresh weights of the root stock seedlings were obtained with 0.75 LF in PV (8.96g/seedling) and CV (7.11g/seedling) mixes. The EC of the both mixes were 0.93 and $1.09dS{\cdot}m^{-1}$, respectively. The fresh weights of the scion seedlings 31 days after seed sowing were 4.29g with 0.50 LF in the PV and 3.13g with 0.50 LF in the CV. The root medium ECs of the two treatments were 0.76 and $1.34dS{\cdot}m^{-1}$, respectively. Fresh weights of the seedling grafts grown for 31 days were greatly influenced by post-planting fertilizer concentrations. The heavier plants were obtained in $100mg{\cdot}L^{-1}$ N treatment than any other treatments in same mixes. The substrate ECs in these two treatments were 0.98 and $1.93dS{\cdot}m^{-1}$, respectively, indicating that the desirable range of soluble salts in soil extracts is higher in the CV mix than the PV mix. Results of this study suggest that optimum EC range is different in each medium and LF need to be adjusted differently for each root medium to produce high quality seedling grafts of tomato.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.247-252
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• 2011

Electrical conductivity, drainage, and irrigation amount of nutrient solution are important factors for determination of the mixing ratio of fresh and reused nutrient solutions in closed-loop soilless culture. Generally a fixed mixing ratio is applied in commercial scale greenhouses using solar radiation-based irrigation system. Although it ensures continuous supply of fresh nutrient solution in the mixing process, occasional discharge of the drainage is inevitably required. This study was conducted to compare the nutrient replenishing effect under different mixing processes and to investigate appropriate mixing process. For this experiment, a fixed mixing ratio (FR), modifiable mixing ratio (MR), and open-loop (OP) as control were applied. Mixing ratio was determined by a set value of EC for dilution of collected drainage in FR and the set values of 1.0 and $2.0dS{\cdot}m^{-1}$ were used as treatments (FR 1.0 and FR 2.0), respectively. In MR, mixing ratio was determined based on EC and volume of drainage within irrigation volume per event. The volume of drainage stored in the drainage tank tended to increase in FR 1.0. Although such trend was not observed in FR 2.0 and MR, the volume of drainage stored in MR was lower than that in FR 2.0. The ion balance of $Mg^{2+}:K^+:Ca^{2+}$ or $SO^{2-}_4:NO^-_3:PO^{3-}_4$ in the drainage and reused nutrient solution changed within a narrow range regardless of treatment.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.497-503
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• 2022

This study was conducted to investigate the horticultural media + decomposed granite + reused rock wool in the following mixing ratio: Control = 100:0, M1 = 80:0:20, M2 = 60:30:10, M3 = 40:30:30, M4 = 30:40:30, M5 = 0:50:50 (reused rockwool : decomposed granite : horticultural media) and develop the physicochemical properties and the growth of 'Sulhyang' strawberry runner plant. In the physical aspect of the horticultural media, statistical differences were recognized that the bulk density and particle density were lower in the control and M1. But the bulk density and particle density were high in the M3, M4, and M5, because it had high mixing ratio between recycled rock wool and decomposed granite. EAW and WBC showed a similar tendency. The air porosity and total porosity were higher in control and M1 than M3, M4, M5. Exchangeable cation (K⁺, Ca²⁺, Na⁺, Mg²⁺) and base replacement capacity (CEC) were higher in control and M1, than M2, M3, M4, and M5. As a result of the cultivation of 'Sulhyang' runner plant, the plant length was long in M2, 32.1 cm and smaller than M5 to 28.4 cm. However, if the crown diameter, which is the growth indicator of the runner plant, all 6 treatments were formed 11.23 mm-12.03 mm, which is considered to be suitable for the growth of the runner plant. There wasn't a statistical difference between the weight and dry weight of the root. As a result, the growth difference of the seedlings by the horticulture media was similar. Therefore, considering the physical properties of the horticultural media, it was judged that the air porosity and total porosity would be improved when the recycled rock wool and the decomposed granite were properly mixed rather than the use of the horticultural media as a single medium, which would be advantageous for irrigation management.