• Korean Journal of Soil Science and Fertilizer
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• v.35 no.1
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• pp.1-11
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• 2002

Root distribution was monitored in the root zone of corn fields on several soil series in central Illinois during three growing seasons in order to find the effect of soil series and tillage system on root growth. A minirhizotron technique was used to videotape each soil profile in weekly intervals to a depth of 75 cm under conventional tillage (CT) and no tillage (NT) systems of cultivation. Root distribution near soil surface generally increased during the early stages of the growing season, but declined as surface soil moisture was depleted in late summer. Even though root distribution was not significantly different between soil series in this experiment. differences in root distribution between soil series were associated with the increases in root-available water storage capacity. Root population in the top 30 cm of NT plots. where increased water infiltration rates and saturated flow of soil moisture into the subsoil, was generally higher than that of CT plots in Illinois corn fields. Foots appeared in the deeper layers later in the growing season, with root penetration into subsoil layers occurring as much as 2-3 weeks earlier on the NT plots than in CT plots. In conclusion, root distribution was significantly affected by the tillage systems, but not different by soil series.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.6
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• pp.836-842
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• 2009

The objectives of this study were to evaluate potential benefits of intercropping of corn with runner bean for a smallsized farming system, based on land equivalent ratio (LER) and silage yield and quality of corn intercropped with runner bean (Phaseolus vulgaris L.), in arid conditions of Turkey under an irrigation system. This experiment was established as a split-plot design in a randomized complete block, with three replications and carried out over two (consecutive) years in 2006 and 2007. Seven different mixtures (runner bean, B and silage corn sole crop, C, 10% B+90% C, 20% B+80% C, 30% B+70% C, 40% B+60%C, and 50% B+50%C) of silage corn-runner bean were intercropped. All of the mixtures were grown under irrigation. The corn-runner bean fields were planted in the second week of May and harvested in the first week of September in both years. Green beans were harvested three times each year and green bean yields were recorded each time. After the 3rd harvest of green bean, residues of bean and corn together were randomly harvested from a 1 $m^{2}$ area by hand using a clipper when the bean started to dry and corn was at the dough stage. Green mass yields of each plot were recorded. Silages were prepared from each plot (triplicate) in 1 L mini-silos. After 60 d ensiling, subsamples were taken from this material for determination of dry matter (DM), pH, organic acids, chemical composition, and in vitro DM digestibility of silages. The LER index was also calculated to evaluate intercrop efficiencies with respect to sole crops. Average pH, acetic, propionic and butyric acid concentrations were similar but lactic acid and ammonia-N levels were significantly different (p<0.05) among different mixtures of bean intercropped with corn. Ammonia-N levels linearly increased from 0.90% to 2.218 as the percentage of bean increased in the mixtures up to a 50:50 seeding ratio. While average CP content increased linearly from 6.47 to 12.45%, and average NDF and ADF contents decreased linearly from 56.17 to 44.88 and from 34.92 to 33.51%, respectively, (p<0.05) as the percentage of bean increased in the mixtures up to a 50:50 seeding ratio, but DM and OM contents did not differ among different mixtures of bean intercropped with corn (p>0.05). In vitro OM digestibility values differed significantly among bean-corn mixture silages (p<0.05). Fresh bean, herbage DM, IVOMD, ME yields, and LER index were significantly influenced by percentage of bean in the mixtures (p<0.01). As the percentage of bean increased in the mixtures up to a 50:50 seeding ratio, yields of fresh bean (from 0 to 24,380 kg/ha) and CP (from 1,258.0 to 1,563.0 kg/ha) and LER values (from 1.0 to 1.775) linearly increased, but yields of herbage DM (from 19,670 to 12,550 kg/ha), IVOMD (from 12,790 to 8,020 kg/ha) and ME (46,230 to 29,000 Mcal/ha) yields decreased (p<0.05). In conclusion, all of the bean-corn mixtures provided a good silage and better CP concentrations. Even though forage yields decreased, the LER index linearly increased as the percentage of bean increased in the mixture up to a 50:50 seeding ratio, which indicates a greater utilization of land. Therefore, a 50:50 seeding ratio seemed to be best for optimal utilization of land in this study and to provide greater financial stability for labor-intensive, small farmers.

• The Korean Journal of Pesticide Science
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• v.3 no.3
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• pp.54-59
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• 1999

The objective was to know if corn growers at Hongchcel County, Kangwon-do, where corn is the major agricultural product, control weeds effectively and use herbicides properly to control weeds. Sixty-eight corn growers at Hongchon were participated in this survey. Corn growers have noxious weeds, such as hairy carbgrass, common purslane, lambsquarters, Asiatic dayflower, mugwort and barnyard grass in their corn fields. Forty-four percents of the answered corn growers control weeds by hand weeding, and the others by a combination of physical and chemical methods. Corn growers have a preference of paraquat and alachlor for a pre-emergence treatment (94% of the answered) and of paraquat, glufosinate, glyphosate and fluazifop-P-butyl for a post-emergence treatment (87% of the answered). Corn growers did not select and use herbicides in a proper manner. fifty-four percent of the answered corn fevers selected herbicides by their own experience and 18 percent by neighbors recommendation. Herbicides were not selected and used in a proper manner by corn growers: 54 percent of the answered selected herbicides by the experience of growers and 18 percent by the recommendation of neighbors. In addition, a half of the answered applied over two-fold higher amounts of herbicides than the recommended rate. With these improper- selection and use of herbicides, 37 percent of the answered have experienced the crop damage and 42 percent the herbicide poisoning. We conclude that the development of the educational program for the proper selection and use of herbicides is needed for corn growers in Kangwon-do.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.111-116
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• 2013

This experiment was carried out to select a resistant corn variety for rice black-streaked dwarf virus (RBSDV) disease in a RBSDV prevalent area (Gochang of Jeollabukdo) from 2006 to 2008. Ten corn varieties for silage preparation were cultivated with first cropping and second cropping system in an RBSDV field, and were tested outbreak rates of RBSDV and dry matter (DM) yield of forage. The outbreak rates of RBSDV were significantly different between corn varieties. Therefore, the resistance degree of corn varieties for RBSDV were divided into 4 groups; very resistant ('Kwangpeyongok' and 'Kwanganok'), resistant ('P3156' and 'P3394'), mildly resistant ('Cheonganok' and 'P32P75') and susceptible ('Suwon19', 'DK697' and 'GW6959') groups respectively. DM yield of forage in RBSDV fields exhibited comparatively significant differences between varieties (p<0.05). DM yield of resistant varieties ('Kwangpeyongok', 'Kwanganok', 'P3156' and 'P3394'), were higher (14~26%) than those of susceptible varieties ('Suwon 19', 'DK697' and 'GW6959'). Therefore, resistant varieties were recommended for increasing forage productivity in field of RBSDV prevalent areas.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.1-8
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• 1998

To compare different methods for the determination of available soil P in the relationship between the soil P and plant uptake of P, rice and corn were cultivated in the pot filled with soils of different available P contents. The soils were taken from 20 rice fields and 20 upland soils. The available soil P were determined before the experiment by Olsen, Lancaster, Bray 1, Bray 2, Mehlich II and Calcium lactate methods and the correlations between the available soil P measured by different methods and the amount of P taken up by corn at 10 leaf stage and by rice at maximum tillering stage were investigated. In upland soils, the available P measured by all the methods was linearly regressed with high significance to the amount of P taken up by corn. The coefficients of determination($R^2$) in the regression equations ranged from 0.596(Calcium lactate method) to 0.891(Olsen method). In rice soils, the soil available P did not regressed by first-order to the amount of P taken up by rice plant, while Michaelis-Menten equation better explained the relationship between the two parameters. In the Michaelis-Menten equation the coefficients of determination for each analytical method ranged from 0.607(Mehlich II method) to 0.923(Lancaster method). Based upon these observations it is concluded that for testing of available P for corn soils Olsen, Bray 2 and Lancaster methods are equally superior to other methods. For rice soils Lancaster, Bray 1, and Bray 2 methods are better than others.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.3
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• pp.109-121
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• 2020

Converting the agricultural land-use of rice field to upland has been increasingly conducted as farmers encourages themselves to grow higher value-added crops on rice fields under the policy support. Comparing to rice field, Upland shows different characteristic of discharge due to the slope, scale, and shape of field and characteristics of rainfall event. In this study, we designed the experiment fields reflecting flat-upland characteristics with different land scale, and tried to collect the discharge and load data. Soybeans and corn were selected as target crops considering the possibility of large-scale cultivation and crop demand. The cultivation was conducted during the growth period in 2019 with 3 different field scales. Hence, we have collected the discharge data from 17 rainfall events and the load data for 8 rainfall events. As a result, the magnitude of rainfall events and the discharge duration were found to have a strong positive correlation and field discharge occurred during the period by 55% to 83% of rainfall duration. Besides we found other relationships and characteristics of rainfall event, discharge, and pollutant load and also pointed out that continuous monitoring and more data are required to derive statistically significant results. Compared with slope-field monitoring data obtained from the precedent research, the runoff ratio of the flat-fields was significantly lower than slope-fields. Overall the discharge in the slop and flat-fields shows appreciably different characteristics so that the related researches need to be further conducted to reasonably assess environmental impact of agricultural activities at flat-field.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.4
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• pp.201-210
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• 1992

This study was designed to investigate the content of inorganic nitrogen($NH_4$, $NO_3$) and its change in the 7 different sites; the permanent meadows of alfalfa, orchardgrass, and reed canarygrass, the fields of rye. corn, rice and a mountain region. the results from this study were summarized as follows; 1. The contents of ammonium and nitrate in meadows were 15.89-16.46 and 1.32-1.86ppm, respectively, showing the lower level than in other sites and no significant diffirences among three meadows. 2. In the rice field, the average content of ammonium(7.19ppm) was the highest among all sites, but the content of nitrate(1 l.l7ppm) was the lowest. In addition, almost all of nitrate were spreaded around the surface. 3. In the mountain region, the content of $NH_4$(5.79ppm) was slightly high, but the content of nitrate ( 15.18ppm) was very low. 4. In the rye field. the average content of $NO_3$ was 35.46ppm and show the highest (92.63ppm) at the deep part of soil in the specific season, but it decreased with increasing temperature. 5. In the corn field, which kept bare after harvesting the corn silage, the content of $NO_3$ was high, regardless of seasons and depths, and increased up to maximum of 103ppm. 6. The ground water concentrations of $NO_3$ were not more than 50ppm in the pasture. In the vegetable house, they were less than 30 ppm during the winter and spring and were 80-100ppm during the summer and fall. 7. The concentrations of $NO_3$ in Han river water were lower during the winter and spring(20-30ppm) and higher dxring the summer and fall (50-90ppm).

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.359-367
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• 1998

In order to determine the nitrogen supplying capabilities (NSC) of corn fields, 47 field experiments were performed in Pennsylvania over 3 year from 1986 and NSCs were estimated by the regression analysis with chemical properties and soil attributes. Although the content of $NO_3-N$ in soil showed the best correlation with NSC ($R^2=0.518$), the standardized partial regression coefficient of $NO_3-N$ for NSC was 0.52, with some variations over the years. This value was slightly higher than those of the other properties which ranged from 0.001 to 0.351. Multiple linear regression with soil attributes for the evaluation of NSC was better than simple regression with $NO_3-N$. The coefficient of determination ($R^2$) for the evaluation of NSC was gradually increased; 0.599 with selected chemical properties, 0.698 with quantitative attributes(chemical properties and depth of Ap horizon), and 0.839 with quantitative and selected qualitative soil attributes. Consequently, in order to evaluate NSC, analysis by multiple linear regression with soil attributes was more reliable and better model than by the simple regression model.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.275-281
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• 2022

We investigated the occurrence pattern of the Asian Corn Borer, Ostrinia furnacalis in job's tears, and we tested the field control effects of 5 insecticides and 3 eco-friendly materials. Adults of O. furnacalis began to occur in May and have passed three generations until the end of October. As results of the field test, five insecticides (novaluron, lufenuron, spinetoram, cyclaniliprole, flufenoxuron) and three eco-friendly materials (gosam extracts 90%, neem extracts 60%, citronella oil 30 + derris extracts 20 + cinnamon extracts 10%) showed high control effects against O. furnacalis in two different areas, and no phytotoxicity even at double dose of pesticides.

• Journal of Biosystems Engineering
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• v.30 no.1 s.108
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• pp.45-55
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• 2005

Knowledge of the relationship between crop yield and yield-limiting factors is essential for precision farming. However, developing this knowledge is not easy because these yield-limiting factors are interrelated and affect crop yield in different ways. In this study, data for grain yield and yield-limiting factors, including crop chlorophyll content, soil chemical properties, and topography were collected for a small (0.3 ha) rice paddy field in Korea and a large (36 ha) upland corn field in the USA, and relationships were investigated with path analysis. Using this approach, the effects of limiting factors on crop yield could be separated into direct effects and indirect effects acting through other factors. Path analysis provided more insight into these complex relationships than did simple correlation or multiple linear regression analysis. Results of correlation analysis for the rice paddy field showed that EC, Ca, and $SiO_2$ had significant (P<0.1) correlations with rice yield, while pH, Ca, Mg, Na, $SiO_2,\;and\;P_2O_5$ had significant correlations with the SPAD chlorophyll reading. Path analysis provided additional information about the importance and contribution paths of soil variables to rice yield and growth. Ca had the highest direct effect (0.52) and indirect effect via Mg (-0.37) on rice yield. The indirect effect of Mg through Ca (0.51) was higher than the direct effect (-0.38). Path analysis also enabled more appropriate selection of important factors limiting crop yield by considering cause-and-effect relationships among predictor and response variables. For example, although pH showed a positive correlation (r=0.35) with SPAD readings, the correlation was mainly due to the indirect positive effects acting through Mg and $SiO_2$, while pH not only showed negative direct effects, but also negatively impacted indirect effects of other variables on SPAD readings. For the large upland Missouri corn field, two topographic factors, elevation and slope, had significant (P<0.1) direct effects on yield and highly significant (P<0.01) correlations with other limiting factors. Based on the correlation analysis alone, P and K were determined to be nutrients that would increase corn yield for this field. With the help of path analysis, however, increases in Mg could also be expected to increase corn yield in this case. In general, path analysis results were consistent with published optimum ranges of nutrients for rice and com production. We conclude that path analysis can be a useful tool to investigate interrelationships between crop yield and yield limiting factors on a site-specific basis.