• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.342-361
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• 2022

In order to evaluate the effect of nitrogen application levels on yield and quality of rice varieties, a field experiment was conducted at National Institute of Crop Science of Korea from 2018 to 2020. Five levels (0, 3, 5, 7, and 9 kg/10a) of nitrogen fertilizer were treated to 21 Korean rice varieties. Yield, yield component, appearance quality, and protein content in rice were analyzed. The average head rice yield for 3 years decreased by 28%, 22%, 11%, and 8%, respectively, when cultivated with 0, 3, 5, and 7 kg/10a nitrogen application compared to cultivation with a standard nitrogen application amount, 9 kg/10a. The number of panicles per hill increased as the amount of nitrogen application increased, but there was no significant change in the number of grains per panicle and 1000-grains weight, and the number of panicles per hill showed relatively small annual variation compared to other yield components. There was no significant difference in the head rice ratio according to the nitrogen application amount, the broken rice ratio slightly decreased, and the floury rice ratio increased. The protein content of rice decreased with increasing nitrogen application in 2018 and 2019, and was the lowest at 7 kg/10a of nitrogen application, and showed a tendency to increase again at 9 kg/10a. In the case of 2020, as the amount of nitrogen application increased, the protein content showed a tendency to continuously increase. In terms of varieties, 13 varieties, including Chilbo, seemed to be capable of low-nitrogen cultivation because loss of the head rice yield was less and the protein content could be lowered to 6% or less according to 7 kg/10a nitrogen application.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.3
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• pp.220-226
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• 1990

This experiment was carried out to study the effects of Bradyrhizobium moculation and fertilizer N application on symbiotc $N_2$ fixation of peanut (Arachis hypogaea L. cv. Younghotangkong) at newly reclaimed soil. Treatments consisting of B. sp. (Vigna) HCR-3 and HCR-46 with control and five levels of nitrogen (0, 4, 8, 16, 32kg/10a) were arranged with split design of four repetitions. The results obtained were as follows. The number of viable Bradyrhizobium in rhizosphere was decreased to 20 days after sowing and thereafter it was remarkably increased, until full ripe stage of pods, decreased as fertilizern rates increased. Nodulation and nitrogenase activity were reduced with increasing levels of fertilizer, whereas top dry matter and nitrogen accumulation where increased. Seed yield of Bradyhizobium inoculation under the fertilizer N zero level was similar to that N : 8kg/10a under uninoculation. It suggested that Bradyrhizobium inoculation could replace the effect of nitrogen application.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.347-352
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• 1987

This studies were carried out to investigate the effects of nitrogen fertilizer rates and methods of its application on maturity of leaves, total nitrogen and total alkaloids concentration in burley tobacco leaves. Nitrogen rate ranged from 17.5 to 40.5kg/10a and applied through basic fertilization and sidedressing. The filling capacity of cured leaves was decreased with increasing levels of nitrogen fertilizer. As the rate of nitrogen fertilization was increased or sidedressing, the maturity of leaves was delayed and total alkaloids and total nitrogen concentration were increased. Total alkaloids concentration in leaves was gradually increased, especially more in upper leaves from 60 to no days after tratnsplanting, but total nitrogen concentration was decreased.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.486-493
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• 2002

본 연구에서는 정밀시비를 위한 전자지도 작성 시스템을 개발하고, 질소 시비량 지도를 작성하였다. 개발된 토양 유기물 함량 계측 센서는 0.07%~7.96%가지의 토양 유기물 함량을 $R^2$= 0.85, SEP=0.72, bias=-0.13으로 계측할 수 있었으며, 작성된 시비량 지도를 이용한 시비는 58.7%의 정확성을 보였다. 시비량 지도에 의한 정밀시비는 획일적인 시비의 정밀시비 30.5%에 비해 91%의 정확성 향상을 보였다. 그러나 개발된 센서의 오차로 인하여 유기물 함량 등급 분류 간격이나 격자 간격 면에서 세분화된 지도는 작성할 수 없었다. 좀 더 정확하고 세분화된 시비량 지도 작성을 위해서는 오차 범위가 작은 정밀한 센서의 개발이 요구된다. 또한 토양 유기물 센서뿐만 아니라 다른 토양 상태를 계측할 수 있는 센서들이 개발된다면 다양하고 정확한 시비량 지도를 작성할 수 있을 것으로 판단된다. 작성된 전자 지도는 농작업의 의사결정에 도움을 주며, 빠른 처방이 가능할 것이다.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.74-82
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• 2004

This study was conducted to estimate the optimum application rate of fertilizer N based on $NO_3-N$ concentration in soils for tomato (Lycopersicon esculentum Mill.) cultivation in plastic film house. Tomato plants were cultivated with and without fertilizer in twelve soils which have different concentrations of $NO_3-N$ ranging from 46 to $344mg\;kg^{-1}$. Dry weight (DW) of above-ground part of tomato with no fertilizer ranged from 28.9 to $112.5g\;plant^{-1}$, depending on N-supplying capability of soils. The soil $NO_3-N$ was positively correlated with DW ($r=0.83^{**}$) and N uptake ($r=0.78^{**}$) by tomatoes in no fertilizer treatment, and negatively correlated with fertilizer effciencies resulted from the differences of DW and N uptake between fertilized and non-fertilized plot. The relationships between soil $NO_3-N$ concentration and DW, N uptake, and fertilizer efficiency were analyzed to determine the critical levels of soil $NO_3-N$ for tomato cultivation. The limit critical levels of soil $NO_3-N$ were estimated to be more than $280mg\;kg^{-1}$ for no application of fertilizer N and to be less than $50mg\;kg^{-1}$ for recommended application of fertilizer N. These critical levels of soil $NO_3-N$ were nearly the same as those calculated from regression equation between electrical conductivity(EC) and soil nitrate for critical levels of EC in recommendation equation of fertilizer N for tomato under the plastic film house by NationaI Institute of Agricultural Science and Technology. Consequently, the optimal application rate of ferdilizer N for tomato cultivation in the soils containing $NO_3-N$ concentration between $280mg\;kg^{-1}$ and $50mg\;kg^{-1}$ was estimated by the equation Y = -0.4348X＋121.74, where Y is the percent(%) to the recommended application rate of N fertilizer and X is the soil $NO_3-N$ concentration ($mg\;kg^{-1}$).

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.218-224
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• 2001

To find out the optimum level of slow release N fertilizers (MS 10, MS S10, LCU 80, and LCU 100), total amount of nitrogen required throughout the growing season were applied in the seedling box or incorporated into paddy soil. Four levels of the slow release N fertilizers (0, 6, 9 and 12 kg N/10 a) were mixed with commercial rice nursery bed soil. N release rate and electrical conductivity(EC) of the slow release fertilizers were greater in the order of MS 10 > LCU 80 ${\fallingdotseq}$ LCU 100 > MS S10 and higher as temperature increased. No seedlings were emerged in all MS 10 plots. The seedling emergence rate of LCU 80 and LCU 100 decreased as the N level increased and seedlings were wilted severely on the 13th day after sowing at 9 and 12 kg N/10 a. In MS S10 plots the emergence rate was higher than 80% at all N levels and seedling growth was normal until 30 days after sowing. Yield of rice was similar between seedling box application and soil incorporation in paddy of MS S10. Yield of rice among the 6, 9, 12 kg N/10 a of MS S10 and conventional 12 kg N/10 a of urea split application was similar, but it was significantly higher compared with no N plot. Fertilizer N recovery of MS S10 decreased as fertilizer level increased and it was significantly higher compared with conventional urea split application.

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.2
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• pp.87-92
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• 2015

This experiment was conducted to evaluate the effect of seeding methods and application levels of nitrogen fertilizer on the yield and forage quality of whole crop rice (WCR). The WCR variety "Namil" was directly seeded on April 25 and transplanted on May 25. Five levels of nitrogen fertilizer were applied (90, 110, 140, 170 and 200 kg/ha). There were no significant differences (p<0.05) of the emergence date, heading date and disease resistance based on the nitrogen fertilizer rates; however, the WCR became dark at higher nitrogen fertilizer rates. The plant height increased at higher nitrogen fertilizer rates and the tiller number showed the same trend. In contrast to a direct seeding method, transplanting increased the tiller number. The dry matter (DM) content did not show a certain tendency based on nitrogen fertilizer rates, while the fresh and dry matter yields increased with incremental changes of the nitrogen fertilizer rates (p<0.01), and the transplant method increased the yield size. In yield analysis, the plot direct-seeded with 140 kg N/ha and the transplanting with 170kg N/ha showed the highest yields. The crude protein (CP) content increased with higher nitrogen fertilizer rate, but there was no significant differences between transplant and direct-seeding methods. The content of ADF (acid detergent fiber) and NDF (neutral detergent fiber) increased with higher nitrogen fertilizer rate, but total digestible nutrient (TDN) content decreased with increased nitrogen levels. Although high nitrogen applications increased the fresh and DM yields, the 140 kg/ha nitrogen fertilizer level is recommended as the proper nitrogen fertilizer level, considering both yield and the environments.

• Weed & Turfgrass Science
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• v.3 no.2
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• pp.137-142
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• 2014

This study was conducted to investigate the effect of silicate mixed with nitrogen fertilizer on improving the growth and reducing nitrogen input of zoysiagrass. Plant height, fresh and dry weight of shoots, roots, and stolons, the number of shoots and total of stolons length were increased with highest in silicate mixed with nitrogen 24 kg/10a than nitrogen 24 kg/10a, and it showed no significance in silicate mixed with nitrogen 18 kg/10a. Nitrogen use efficiency in mixed silicate fertilizer was increased by 25-30% than single nitrogen fertilization. Moreover, the contents of available $SiO_2$, and organic matters of silicate fertilization on soil was higher than not silicate fertilization on soil. The silicate enhanced the growth and density of zoysiagrass, while it was a crucial factor to affect the chemical property of the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.83-90
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• 2004

A pot experiment was conducted to find out the effects of nitrogen content of irrigation water and soil EC on lettuce growth under plastic film house conditions. The square-pots with 42 x 54.5 x 22 cm in length, width and height, were filled with two different soils of different EC. Lettuce was grown with different nitrogen fertilizer application levels including non fertilization (Non-F), decrement of 50% of nitrogen fertilizer recommended by soil testing (DNFRST-50) and fertilization recommended by soil testing (FRST). Two kinds of irrigation water of different nitrogen contents, $6.6mg\;L^{-1}$ and $21.0mg\;L^{-1}$, were used for the experiment. In the low EC soil irrigated with low nitrogen water, fresh weights of lettuce were 6,733, 11,933 and $12,733kg\;ha^{-1}$ for the treatments of Non-F, DNFRST-50 and FRST, respectively. While with high nitrogen water, the yields were 9,733, 13,400 and $12,800kg\;ha^{-1}$, respectively. In the high EC soil irrigated with low nitrogen water, lettuce yields of the Non-F, DNFRST-50 and FRST treatments were 12,400, 12,867 and $10,400kg\;ha^{-1}$, respectively, and with high nitrogen irrigated water lettuce yields of the Non-F, DNFRST-50 and FRST treatments were 13,600, 14,067 and $10,733kg\;ha^{-1}$, respectively. Nitrogen uptake of lettuce from ferilizer in DNFRST-50 was higher than of FRST. Nitrogen uptake of lettuce from irrgation water was found in soils of low EC, but it was not found in soils of high EC. These results suggest that both soil EC and nitrogen content of irrigation water should be considered when we recommend the level of fertilizer application for lettuce.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.397-404
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• 2015

This study was conducted to find out the optimum nitrogen fertilization for production of good quality and high yield zoysiagrass (Zoysia japonica Steud.), the changes in chemical properties of soil in pot and field experiments treated with different levels of nitrogen fertilizer. In pot experiment, the fresh and dry weights of shoots and stolons and the number of shoots increased as nitrogen levels increased, and showed no significant between 24 and $48kg\;N\;10\;a^{-1}$. In field experiment, the shoot length, fresh and dry weights of shoots, roots and stolons, the number of shoots and total stolons length linearly increased as affected by increased nitrogen application, and were not significantly different between 24 and $32kg\;N\;10\;a^{-1}$. In both experiments, pH and exchangeable cations ($Ca^{2+}$ and $Mg^{2+}$) in soil decreased as the rate of nitrogen application increased. As a results, chemical properties of soil were more deteriorated in the plots of higher nitrogen fertilizer rate. Thus, these results demonstrated that the nitrogen fertilizer rate for maximum growth of zoysiagrass was $24kg\;N\;10\;a^{-1}$ in consideration of growth and soil condition.