• Asian-Australasian Journal of Animal Sciences
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• v.21 no.2
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• pp.214-219
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• 2008

An experiment was conducted to evaluate the effects of nitrogen (N) level on the dry matter (DM) yield, N concentration and oxalate content of some tropical grasses, namely Rhodesgrass (Chloris gayana), Guineagrass (Panicum maximum) and Sudangrass (Sorghum vulgare). Three levels of N as urea were applied (Standard- 260, $Standard{\times}2$- 540 and$Standard{\times}4$- 1,060 kg N/ha for Rhodesgrass; Standard- 380, $Standard{\times}2$- 770 and $Standard{\times}4$- 1,570 kg N/ha for Guineagrass and Sudangrass) in a completely randomized design and grasses were harvested twice at approximately two-month intervals. Dry matter yield tended to be higher with increased rate of N fertilizer in all species, while further additional N ($Standard{\times}2$ or $Standard{\times}4$) did not significantly (p>0.05) further increase DM yield, when compared with the Standard level of N fertilizer application. There was also a trend towards higher N concentration in plants as N fertilization increased in all species and it was increased significantly in Rhodesgrass and Sudangrass (p<0.05 or p<0.01, respectively). Further additional N ($Standard{\times}2$ or $Standard{\times}4$) application showed no significant (p>0.05) differences on oxalate content in plant tissue within species, when compared with the Standard level of N. The Rhodesgrass contained 0.11, 0.13 and 0.15% soluble oxalate and 0.23, 0.25 and 0.27% total oxalate with Standard, $Standard{\times}2$ and $Standard{\times}4$ level of N application, respectively. The Guineagrass contained 0.54, 0.50 and 0.42% soluble oxalate and 1.60, 1.56 and 1.45% total oxalate with Standard, $Standard{\times}2$ and $Standard{\times}4$ level of N application, respectively. The Sudangrass contained 0.06, 0.15 and 0.12% soluble oxalate and 0.22, 0.22 and 0.21% total oxalate with Standard, $Standard{\times}2$ and $Standard{\times}4$ level of N application, respectively The results from this study suggest that these grasses do not use further addition of N fertilizer ($Standard{\times}2$ or $Standard{\times}4$) to form high content of oxalate salts, when compared with the Standard level of N. In addition, the levels of oxalate present with these grasses are quite low as far as toxicity to animals is concerned.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.66-71
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• 1982

Field experiments of nitrogen application (0, 100, 200, 400, 800kg N/ha year) were carried out to study the nitrogen response of Sudangrass at College Farm, Seoul National Univ., in 1979 and 1980. Dry matter yield and leaf area index increased up to 400kg N/ha in 1979 and 800kg N/ha in 1980. The forage yield of 1980 was less than that of 1979, due to the extraordinarily low temperature and the decreased solar radiation during summer. Total nitrogen contents in forage increased with nitrogen application, but maximum contents were found either 400 or 800kg N levels depend on each cutting stages. Nitrate nitrogen content in forage exceded over 2000 ppm at 800kg N application. Overall percentages of N recovery were below 50% with average 34%. Net assimilation rate and nitrogen use efficiency of Sudangrass were improved in higher temperature and more sunlight condition during regrowth period.

• Journal of the Korean Society of Tobacco Science
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• v.14 no.2
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• pp.151-158
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• 1992

Field experiment was conducted to investigate the effects of stalk position, compound fertilizer application rate (N-P2O5-K2O : 10-10-20 : 75, 100, 125kg/03), paddy and upland soil and varieties, NC82 &KF103, on nonvolatile organic and higher fatty acids of flue-cured tobacco. Followed by stalk position, malic, citric, malonic and succinic acid contents were significantly increased with higher stalk position, but oleic and linoleic acid contents were decreased with higher stalk position. The higher application rate of compound fertilizer results in increasing citric, malic, malonic and succinic acid contents, but the contents of higher fatty acids were not significantly influenced by fertilizer application rate. The cured leaf cultivated in paddy soil was higher citric and malic acid contents than in upland soil, but the contents of higher fatty acids have no difference between paddy and upland soil. The variety of KF103 was higher citric and linoleic acid contents than that of NC82, but the contents of higher fatty acids have no difference between varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.226-235
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• 2002

This experiment was to evaluate lodging characteristics of 35 recommended rice varieties of Kyonggi-do at normal (110 kg N/ha) and hen (220 kg N/ha) nitrogen application rates during 1999 to 2000. At heavy N fertilization rate, varieties that were highly resistant to lodging were Obongbyeo, Daejinbyeo, Naepoongbyeo, Nonganbyeo and Ilpumbyeo. Fourteen varieties including Daeanbyeo were moderately resistant and 11 varieties including Jinbubyeo were susceptible to lodging. The lodging-related characters which showed the highest effect on lodging at lodging degree of 9 were culm length and height of center gravity, culm length at lodging degree of 5, and culm length and the third internode length at lodging degree of 3 or below. The difference in rice yield between normal and heavy nitrogen fertilization rate was within 5% in early-maturing varieties but there was great yield difference in mid- and late-maturing varieties depending on the degree of lodging. Consequently, stable rice yield could be obtained by selecting lodging-resistant varieties and lowering fertilization rate, specially in the paddy field where lodging occurrence is common.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.285-299
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• 1987

Timing and placement of fertilizer applications are two managerial means to improve the fertilizer use efficiency. The relative importance of these two means is determined by the application rate. With the realistic rate of N application recommended to the small farmers in the tropics, at present and in the near future, basal application in right manner, seems to be more important than split application at different times. In wetland rice soils, deep placement by whatever available means is desirable. But in the situations where perfect deep placement is very difficult to implement, the whole-layer application may be worth trying, until better methods become available. In rainfed uplands, N fertilizer application plans should be contingent upon the amount and distribution of rainfall: apply a less risky rate as subsurface banding near the crop rows to start with; then, depending upon the rainfall prospects in the season, apply or omit the additional dose. Because the patterns of crop response to N fertilizer can be significantly different between the research farms and farmers' fields, it seems imperative to have information on the patterns of crop response to N under farmers' management conditions, for the development of realistic fertilizer application recommendations. To enable the farmers to adopt improved fertilizer application technologies, it is essential to develop and make available to farmers convenient fertilizer applicators. Past experience with the improved fertilizer use technologies indicates that, in the long run, the development of fertilizers that are not only effective and convenient for farmers to use but also easy to produce without major modifications of existing fertilizer production systems is the ultimate solution to the problem of low N fertilizer use efficiency.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.2
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• pp.75-80
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• 2001

This study was conducted to identify the optimum proper nitrogen (N) application rate for tillering in ridge direct seeding on dry paddy of rice culture. During 1998, a series of experiments was carried out at paddy field (Chonbuk series) of the National Honam Agricultural Experiment Station, RDA using Dongjinbyeo. Leaf area index and top dry weight increased with higher N levels, especially in the 100 kg/ha seeding rate compared with the 60 kg/ha seeding rate. N use efficiency increased at increased by 50~75% of the N topdressing rate at tillering. Heading date, ripened grain rate, and 1,000-grain weight of brown rice did not vary among the rate of topdressing for tillering and seeding rates. The highest grain number per unit area was at the level of increased by 75% in N topdressing at tillering stage. Milled rice yield increased 5% at the 60 kg/ha seeding rate and increased 16~17% at the 100 kg/ha seeding rate at increased by 50~75% of topdressing N compared with 48 kg/ha topdressed N of 60 kg/ha seeding rate.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.361-361
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, $25kg\;P_2O_5$, $25kg\;K_2O\;ha^{-1}$ while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg $P_2O_5$, $30kg\;K_2O\;ha^{-1}$. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, $120kg\;N\;ha^{-1}$, 0, 25, 30 45, $60kg\;P_2O_5\;ha^{-1}$ and 0, 15, 25, 30, $45kg\;K_2O\;ha^{-1}$. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings $hill^{-1}$ with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and $30kg\;P_2O_5$. The yield was the highest at 15, 30 and $45kg\;K_2O$ followed by $25kg\;K_2O$. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and $30kg\;P_2O_5$ will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.363-363
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, 25kg P2O5, 25kg K2O ha-1 while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg P2O5, 30kg K2O ha-1. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, 120kg N ha-1, 0, 25, 30 45, 60kg P2O5 ha-1 and 0, 15, 25, 30, 45kg K2O ha-1. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings hill-1 with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and 30kg P2O5. The yield was the highest at 15, 30 and 45kg K2O followed by 25kg K2O. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and 30kg P2O5 will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.153-161
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• 2007

Field experiments were conducted to determine the physiological and biochemical basis of the interactive effect of sulphur (S) and nitrogen (N) application on seed and xanthotoxin yield of Ammi majus L. Six treatments were tested ($T_1$ = control-without manure and fertilizers, $T_2$ = manure @ 9 kg $plot^{-1}-10\;t\;ha^{-1},\;T_3=A_0N_{50}K_{25}P_{25},\;T_4=S_{40}N_{50}K_{25}P_{25},\;T_5=S_{40}N_{100}K_{25}P_{25}\;T_6=S_{20+20}N_{50+50}K_{25}P_{25})$). Nitrate reductase (NR) activity and ATP-sulphurylase activity in the leaves were measured at various phonological stages, as the two enzymes catalyze rate-limiting steps of the assimilatory pathways of nitrate and sulphate, respectively. The activities of these two enzymes were strongly correlated with seed and xanthotoxin yield. The highest nitrate reductase activity, ATP-sulphurylase activity and xanthotoxin yield were achieved with the treatment $T_4$. Any variation from this treatment decreased the activity of these enzymes, resulting in a reduction of the seed and xanthotoxin yield in Ammi majus L. The higher seed and xanthotoxin yield achieved in Ammi majus L. at treatment $T_4$ could be due to optimization of leaf soluble protein and photosynthetic rate, as these parameters are Influenced by S and N assimilation.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.258-263
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• 2006

ANAMMOX (Anaerobic ammonium oxidation) reactor, which was cultivated ANAMMOX bacteria in mesophilic condition ($35^{\circ}C$), was operated to investigate the effects of temperature. In $20{\sim}30^{\circ}C$ of operation condition, which was assumed as field-temperature, total N removal and $NH_4-N$ removal rate were declined from about 2.50 and $1.27kg\;N/{m^3}_{reactor}-day$ (0.06 and 0.03 kg N/kgVSS/day) to 1.62 and $0.41kg\;N/{m^3}_{reactor}-day$ (0.04 and 0.01 kg N/kgVSS/day), In this range of temperature, ANAMMOX had very low activities but acid fermentation bacteria and denitrifiers, which were competitors of substrates, had high activities relatively. Though operation temperature was higher than inhibition condition for two months, ANAMMOX activities could not been recovered once they were inhibited by low temperature. This fact was resulted from very slow doubling time of ANAMMOX bacteria. This study shows that maintenance device of optimal temperature is necessary required in field application of ANAMMOX.