• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.92-98
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• 2021

BACKGROUND: Unintentional residual pesticide in soil derived from preceding crops and the transfer to succeeding crops was considered a critical barrier for positive list system (PLS). Thus, an uncertain risk is predicted for ethoprophos applied at cultivation of preceding crop (Korean cabbage) to succeeding crop (spinach). METHODS AND RESULTS: Ethoprophos was treated on soil following the recommended dose and 5 times dose according to the safe use guidelines for Korean cabbage after seeding. On the 4 days after harvesting of preceding crop, spinach was sowed. The initial residual amounts of ethoprophos on soil (7.081-19.493 mg/kg) were decreased to 3.832-7.218 mg/kg until the harvest of Korean cabbage, and then finally decreased to 0.011-0.079 mg/kg after spinach cultivation. The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03% and distributed to root (0.150-0.903 mg/kg) and shoot (0.021-0.151 mg/kg), respectively. The residual amounts of uptake and translocation from preceding crop cultivated soil to spinach edible part were found to be below LOQ. CONCLUSION: The plant back internal (PBI) for ethoprophos is not recommended during sequential cultivation of leafy vegetables, since the residual amounts of ethoprophos in spinach were less than MRL (0.02 mg/kg).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.416-425
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• 2020

This study evaluated the productivity of early maturity silage corns during continuous monocropping and the possibility of expanding forage production. Continuous monocropping of three silage corns, such as Kwangpyeongok (medium maturity), Sinhwangok (early maturity), and Sinhwangok2 (early maturity) was planted twice, in April and July from 2018 to 2019 at Suwon. The number of days from the sowing date to the silking date was 78 for the preceding crop and 52 for the succeeding crop. The number of days from the silking date to the harvesting date was 26 for the preceding crop and 46 for the succeeding crop. The sums of the temperature from the sowing date to the silking date were 1,512℃ for the preceding crop, 1,246℃ for the succeeding crop. The sums of the temperature from the sowing date to the harvesting date were 2,198℃ for the preceding crop and 1,951℃ for the succeeding crop. The dry matter yield of the preceding crop (1,637 kg/10a) was similar to that of the succeeding crop (1,565 kg/10a). The dry matter yields of Sinhwangok2 (1,673 kg/10a), Sinhwangok (1,660 kg/10a) and Kwangpyeongok (1,579 kg/10a) were similar to those of the preceding crop. The dry matter yields of Sinhwangok (1,669 kg/10a) and Kwangpyeongok (1,651 kg/10a) were similar to those of the succeeding crop and Sinhwangok2 (1,374 kg/10a) was the lowest among the three corn varieties. The total digestible nutrients (TDN) yield of the preceding crop (1,135 kg/10a) was similar to that of the succeeding crop (1,037 kg/10a). The TDN yields of Sinhwangok2 (1,183 kg/10a), Sinhwangok (1,158 kg/10a), and Kwangpyeongok (1,063 kg/10a) were similar to those of the preceding crop. The TDN yields of Sinhwangok (1,150 kg/10a) and Kwangpyeongok (1,100 kg/10a) were similar for the succeeding crop and Sinhwangok2 (970 kg/10a) was the lowest among the three corn varieties. The total dry matter yields of Sinhwangok (3,329 kg/10a) and Kwangpyeongok (3,230 kg/10a) were similar, but Sinhwangok2 (3,047 kg/10a) was the lowest among the three corn varieties. The total TDN yields of Sinhwangok (2,307 kg/10a), Kwangpyeongok (2,162 kg/10a), and Sinhwangok2 (2,152 kg/10a) were similar. It was concluded that Sinhwangok and Sinhwangok2 have high TDN yields as well as early maturity, and therefore are advantageous for direct continuous monocropping.

• Korean Journal of Environmental Agriculture
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• v.40 no.3
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• pp.203-210
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• 2021

BACKGROUND: Pesticides can persist in soil due to multiannual uses. To decrease the concerns for potential carry-over of such residues from treated soil during preceding crop cultivation to non-target crops grown in rotation, an uptake study of procymidone was conducted under the actual cultivation conditions in Korea. METHODS AND RESULTS: Procymidone was sprayed twice by foliar application with recommended and double dose according to the safe use guidelines for Korean cabbage up to 14 days before harvest. Arable land was kept fallow for 4 days after harvesting Korean cabbage, and spinach was cultivated as a succeeding crop. Initial residues in soil were 5.670-14.175 mg/kg that were degraded to 3.098-4.555 mg/kg until harvest of Korean cabbage, and then persisted at 1.026-1.300 mg/kg by spinach harvest. Procymidone residues in edible part of succeeding crops from soil uptake were in range of 0.020-0.048 mg/kg for recommended dose and 0.055-0.116 mg/kg for double dose. Root concentration factor (RCF) values of procymidone at different concentration ranged from 0.053 to 0.123, and translocation factor (TF) ranged from 0.176 to 0.768 for spinach. The value of TF was higher than RCF, indicating that the capability of translocation to shoot was relatively higher than that of root uptake and accumulation. CONCLUSION: Procymidone applied on Korean cabbage can be carried-over to spinach and detected at a level similar to MRL (0.05^T mg/kg). Therefore, this study suggests a follow-up study for establishment of plant back interval (PBI) of succeeding crops reflecting the actual agricultural conditions as this study.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.14
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• pp.173-189
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• 1973

The followings are the results obtained in a series of experiments concerning of the varieties, the short-day-treatment, the fertilizer application, and the planting space of soybean, which were carried out to investigate the methods best suited for cultivating green soybean as the preceding crop of the rice. in the paddy-field in the middle parts of Korea at the practice farm attached to Agriculture College of Kon Kuk University in 1972. 1. Though the varieties of soybean was planted on the hot-bed on March 15 and then set in the main plot, none of them did flower within May 15, which is the limit time of flowering in growing soybean as the preceding crop of the rice in the paddy-field without the short-day-treatment being applied during raising seedlings. 2. The earliest-maturing variety groups such as HOKKAl#l, WASEMIDORI, YAEHUSANARI, MIT AKARAHAKUCHO, and VERDE flowered within May 15 by the short-day-treatment during raising seedlings. 3. The optimum hours of the day length was known to be 7 to 9 in the medium-maturing and late-maturing variety groups and 7 to 11 in the early-maturing and the earliest-maturing variety groups in the case of appling the short-day-treatment for 10 days from the beginning of the primary regular compound leaf development. 4 The optimum days in appling the short-day-treatment for 11 hours a day was recognized to be about 10 days regardless of the maturity of varieties. 5. Reduction of days required to flower by the short-clay-treatment, that is, light-sensitivity was remarkably higher in the medium-maturing and the late-maturing variety groups than in the earliest-maturing and the early-maturing variety groups. 6. The yield showed an increase of about 17 per cent in the case of appling the standard amount of nitrogen(4.0 kg/10 a), but it tended to reduce on the contrary in appling the increased amount of nitrogen. 7. The application of increased amount of phosphate had less significant effect on the yield increase than in the case of application of its standard amount( 4.0 kg/l0 a). 8. When the number of transplantation plant was changed from 54 to 130 per 3.3 $m^2$, the yield in 130 plant plot was about two times so higher than in 54 plant plot that the effect of close planting cultivation on the yield was proved to be remarkable. 9. Conditions possible for cultivating green soybean as the preceding crop of the rice in the paddy-field in the middle parts of Korea are turned to be as follows: (a) to plant the earliest-maturing-variety groups on the hot-bed on March 15. (b) to apply the short-day-treatment by 11 hours a day for 16 days from April 16, which is about the time when the primary regular leaf begin to develop. And it was, found to be a most remarkable in the increased yield that apply nitrogen 4.0 kg, phosphate 4.0 kg, and potassium 6.0 kg per 10 a as basic manuring totally and apply the close planting by 130 plants per $3.3{m^2}$(50 cm $\times$ 5 cm).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.335-342
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• 2023

To achieve self-sufficiency in domestic wheat (Triticum aestivum L.), an increase in high-quality wheat production is essential. Given Korea's limited land area, the utilization of cropping systems is imperative. Wheat is compatible with a double cropping system along with rice, soybeans, and corn. Data on alterations in wheat quality following summer crop cultivation is required. This study investigated the impact of cultivating preceding crops such as rice, soybeans, and corn in a wheat cropping system. The analysis focused on the influence of these preceding crops on wheat growth, quality, and soil characteristics, elucidating their interrelationships and impacts. While there were no differences in growth timing and quantity during wheat growth, a significant variance was observed in stem length. Protein content, a key quality attribute of wheat, displayed variations based on the intercropped crops, with the highest increase observed in wheat cultivated after soybeans. Soil moisture content also exhibited variations depending on the intercropping system. The wheat-rice intercropping system, which requires soil moisture retention, resulted in greater pore space saturation in comparison to other systems. Moreover, soil chemical properties, specifically phosphorus and calcium levels, were influenced by intercropping. The highest reduction in soil phosphorus content occurred with soybean cultivation. These findings suggest that intercropping wheat with soybeans can potentially enhance wheat quality in domestic varieties.

• Journal of Climate Change Research
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• v.5 no.2
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• pp.109-125
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• 2014

Suitable climate condition is essential for stable growth of crops which directly leads to an increase in crop production. Preceding domestic researches mostly used crop models to predict grain or crop yield in relation to climate change. However, the use of various models and input data based on foreign background lowered the reliability for result. Therefore in this study, we evaluated domestic applicability by comparing and analyzing various crop models developed abroad. In addition, we selected models based on the possibility of acquiring input data and suggested domestic applicability.

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.167-172
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• 2013

A Two-year field experiment was carried out in 2009 and 2010 to evaluate the effects of different densities of wild oat and nitrogen (N) rates on oilseed rape yield and yield components. Experimental design was split plot with three replications. Increased nitrogen rates up to 150 kg N/ha caused an increase in oilseed rape grain yield in weed-free plots (4.26 t/ha; 1t = $10^3kg$), while even at the lowest density of wild oat (15 $plants/m^2$), increasing N fertilizer only up to 50 kg/ha led to a significant increase in grain yield. Wild oat growth was favored by high levels of N. Intraspecific competition reduced biomass, 100-seed weight and number of tillers of wild oat. Both lower N rate and intraspecific competition had negative effect on wild oat growth but the weed was still able to produce a considerable number of tillers and vigorous seeds. It showed that wild oat possess a notable adaptive plasticity and can allocate a greater proportion of its resource toward reproductive organs even under resource shortage conditions and, thus, it may increase the competitive ability of the weed over the crop.Our results suggest that effective weed management should be done to prevent wild oat seed production in crops preceding oilseed rape as well as to control the weed at early season in oilseed rape fields.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.211-215
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• 2000

Lipid extraction preceding fatty acid methyl esters preparation for gas-liquid chromatography is time-consuming and cumbersome. We performed one-step extraction/methylation method with a mixture of methanol-heptane-benzene-DMP-H$_2$SO$_4$ without prior fat extraction. The simultaneous digestion and lipid transmethylation takes place at 8$0^{\circ}C$ in a single phase. After cooling till room temperature, two phases are formed. The upper one of the phases contains the fatty acid methyl esters ready for GLC. The fatty acid composition of major industrial crops obtained by the one step extraction/methylation method (method 1 and 2) was almost identical with the fatty acid composition of the pure fats extracted with hexane by the Soxtec instrument (method 3). Due to its simplicity, speed, and reduced organic solvent the one-step extraction/methylation method (method 1 and 2) should be useful to determine overall fatty acid composition, especially in situations where many samples have to be analyzed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.51-55
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• 1979

The effects of vernalization and darkness on flower initiation were reviewed by using naked barley varieties. The dark effects were pronounced on flower induction even at 25$^{\circ}C$. There were no differences in flowering responses among varieties. The effects of vernalization and darkness combined with 25$^{\circ}C$were 100% and 60% respectively which showed a significant difference. When the alternation of darkness with light was taken as first and last the flowering rate was 92 percent. When it was intercalated by light treatments the flowering rate was 91 per cent. Thus the effects of vernalization and darkness seems to differ.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.4
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• pp.308-315
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• 2003

A field experiment was conducted to investigate the performance of three legume species in a zero-tillage, non-fertilized rice field in a temperate zone. Before the experiment for 5 years, from 1995 to 1999, plant growth patterns of three legume species grown as over-wintering (October-May) cover crops on a paddy field were maintained to study N balance and $\textrm{N}_2$ fixation. Decrease in plant density accelerated from after winter to flowering from 1,090, 320, and 5 to 732, 232, and 6 plants $\textrm{m}^{-2}$ in Chinese milk vetch (CMV), white clover (WC), and hairy vetch (HV), respectively. Total dry weights of plants above-ground level were 0.05, 0.11, and 2.43 g $\textrm{plant}^{-1}$. in WC, CMV and HV respectively but steeply increased at ripening up to 0.77, 2.33, and 26 g $\textrm{plant}^{-1}$. The root dry weight of HV and CMV rapidly increased while in WC, root dry weight increased slightly towards flowering. The highest nodule numbers were recorded in CMV to April thereafter WC produced the highest. Nodule size was distributed within 7mm in CMV but it was larger in HV varying from 1 to 10mm. Shoot N (g $\textrm{m}^{-2}$) greatly increased from over-wintering to flowering in CMV, HV and WC and it ranged from 1.66, 0.5 and 1.92 to 12.6, 3.1 and 13.02 g $\textrm{m}^{-2}$, respectively. After wintering, the initial shoot N content (%) was more in CMV. Root N content (%) was constant or slightly decreased in HV and WC. Soil total N in the control plot (clean fallow) was the highest on Mar. 2 then decreased rapidly to flowering. Soil N content was constant in HV plots whereas it was low in WC plots for the entire growth period except just after winter. Maximum nitrogenase activities were 9, 37.8, and 131 mol $\textrm{C}_2\textrm{H}_4$ $\textrm{plant}^{-1}$ $\textrm{hour}^{-1}$. in CMV, HV, and WC, respectively. Nitrogenase activity showed a direct correlation with nodule number, size and fresh weight. As a cover crop preceding a rice crop, CMV is more suited to colder regions due to its earlier ripening characteristics. Hairy vetch and WC are recommended for regions with a mild winter and a long summer owing to their late ripening and great N fixation activity.