• Korean Journal of Soil Science and Fertilizer
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• v.42 no.spc
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• pp.33-39
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• 2009

The practice of supplying nutrients for paddy soil with sustaining human health and ecological soundness is to utilize indicators considering soil chemical reactions. The long-term basis experiment of fertilizer and amendment of paddy soil and an experiment of yield response of soil types on nitrogen level from 2000 till 2002were used to search indicators of nutrient supplying capacity related to soil chemical reactions. Chemical reactions of paddy soil was composed of dissociating and/or adsorbing nutrients and of decomposing soil organic matter (SOM) into $H^+$, $e^-$, $CO_2$ in paddy soil. The indicators of nutrient supplying capacity, which were established by considering soil chemical reactions, were SOM or soil protein for nitrogen and available phosphate for phosphorus and cation exchangeable capacity (CEC) and exchangeable potassium for potassium. Korea has used fertilizer recommendation equations established with the indicators of nutrient supplying capacity for paddy soil.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.155-163
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• 1999

Nutrient balance during rice cultivation in the paddy of a local area under the environmental protection for drinking water supply was investigated. To compare nutrient balance in the paddy soil applied with different types of fertilization, 7 treatments were selected as followings : Recommended level of chemical fertilizers(R), Conventional fertilization(CF), Fresh cow manure(FCM), Cow manure compost(CMC), Straw compost+reduced chemical fertilizer(SCF), Fresh straw+recommended level of fertilizers(FSC), and no fertilization as control(C). Here, FCM, CMC and SCF were applied at the same level of total nitrogen as recommended in R. Rice yield was the highest in the recommendation(R) and fresh cow manure (FCM) treatments with $6,730kg\;ha^{-1}$(index 100), and followed by SCF (index 98), FSC (index 98), CMC(index 94), and CF(index 94). But statistically significant difference was not recognized among treatments except the control. Nitrogen infiltration loss was high in the simple chemical fertilizer treatments with $63kg\;ha^{-1}$ in CF and $58kg\;ha^{-1}$ in R during rice cultivation, respectively. Nitrogen infiltration loss was decreased below half level of chemical fertilizer treatments with cow manure treatments ($23kg\;ha^{-1}$ in FCM and $27kg\;ha^{-1}$ in CMC) and with reducing chemical fertilizer treatment by adding straw compost ($25kg\;ha^{-1}$). Phosphate was not leached during rice cultivation in paddy soil of a fluvial deposit type, in which oxidation horizon was developed broadly under around 15 cm depth of surface soil. Phosphate balance (A-B) was closed to 0 in all treatments except cow manure treatment (CMC), in which it was $+30kg\;ha^{-1}$ and show the possibility of over accumulation of phosphate by continuously replicated application of cow manure compost. Potassium balance was negative value in all but straw recycling treatment (FSC). It means that potassium was continuously supplied from soil minerals, uptaken by plants or eluted out of soil. In conclusion, by substituting inorganic fertilizer for organic fertilizer or reducing application rate of chemical fertilizer through mixing organic fertilizer, it would be possible to achieve the same rice yield as in the recommendation treatment and to decrease nutrient leaching below half level in rice paddy soil.

• 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 Soil Science and Fertilizer
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• v.29 no.3
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• pp.282-287
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• 1996

This study was conducted to identify the parameter better representing the nitrogen supply capacity of soils for the vegetable crops growing in vinylhouse. All the parameters showed significant positive correlation with the yield of chinese cabbage. The correlation coefficients were in the order of $NO{_3}^--N+NH{_4}^+-N(2M\;KCl)$ > $NO{_3}^--N(2M\;KCl)$ > OM > T-N > 0.01M $NaHCO_3$ > 0.01M $CaCl_2$ > $NH{_4}^+-N(2M\;KCl)$ > 6N HCl. Between the soil N and N absorbed by plant, the correlation coefficients were in the order of $NO{_3}^--N+NH{_4}^+-N(2M\;KCl)$ > $NO{_3}^--N(2M\;KCl)$ > 0.01M $NaHCO_3$ > $NH{_4}^+-N(2M\;KCl)$ > 0.01M $CaCl_2$ > OM > T-N > 6N HCl. The results of this study suggest that 2M KCl extractable inorganic N. 2M KCl extractable $NO{_3}^--N$ are recommendable parameters for the estimation of N supply capacity of the vinylhouse soils. The sum of soil $NO{_3}^--N$ and fertilizer nitrogen showed highly significant positive correlation with the yields of chinese cabbage and nitrogen absorbed by the plant, while negative correlation with the nitrogen use efficiency.

• Korean Journal of Organic Agriculture
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• v.15 no.4
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• pp.399-411
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• 2007

Korean organic farming has been well developed over the last two decades. It demonstrates that the number of certificated farm for organic agriculture and products have been drastically increased in recent year. However, the organic farmers have thought that organic farming rely only on organic fertilizer and they don't keep organic farming principle in which organic farmer should enhance biological activity and crop rotation. This study was to compare nutrient input, recommendation, cropping system and organic product circulation between the early $20^{th}$ century and beginning of the $21^{st}$ century. The population of Korea has increased 7.3 times more than that of a century ago but cultivated land has been decreased during 100 years. The rice production in 2002 was 4.2 times higher than that of production in 1912. The input of N, P and K in 1907 on the basis of King's suggestion was 95.6kg/ha, 15.9kg/ha and 3.0kg/ha, respectively. Nitrogen came from excreta (40%), green manure (55%) and compost (5%) in the early 20th century. On the other hand, organic farmer input organic resources such as wood chip (30.1%), compost (27.8%), rice straw (14%) and others (25%) these days. In terms of nutrient balance calculated nutrient and absorption by plants, organic rice farmer apply excessive nitrogen and phosphorus to the soil. They was used to put $7{\sim}10$ times more nitrogen than that of a century ago. Nutrient recommendation was similar in N and P between early 20th century and early $21^{st}$ century. Farmers in both century did not rotate crops in the field. Today, organic farmers engaged in more continuous cultivation than in early 20th century. Farmers in the early $20^{th}$ century produced locally, consumed locally the agricultural products, but organic farmers in the $21^{st}$ century produce the organic product in the local farmland and consumed in the large city and also a lot of foreign organic products have been imported in recent year.

• Journal of Crop Science and Biotechnology
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• v.10 no.1
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• pp.33-38
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• 2007

Nitrogen management at the panicle initiation stage(PI) should be fine-tuned for securing a concurrent high yield and high quality rice production. For calibration and testing of the recommendation models of N topdressing rates at PI for target grain yield and protein content of rice, three split-split-plot design experiments including five rice cultivars and various N rates were conducted at the experimental farm of Seoul National University, Korea from 2003 to 2005. Data from the first two years of experiments were used to calibrate models to predict grain yield and milled-rice protein content using shoot fresh weight(FW), chlorophyll meter value(SPAD), and the N topdressing rate(Npi) at PI by stepwise multiple regression. The calibrated models explained 85 and 87% of the variation in grain yield and protein content, respectively. The calibrated models were used to recommend Npi for the target protein content of 6.8%, with FW and SPAD measured for each plot in 2005. The recommended N rate treatment was characterized by an average protein content of 6.74%(similar to the target protein content), reduced the coefficient of variation in protein content to 2.5%(compared to 4.6% of the fixed rate treatment), and increased grain yield. In the recommended N rate treatments for the target protein content of 6.8%, grain yield was highly dependent on FW and SPAD at PI. In conclusion, the models for N topdressing rate recommendation at PI were successful under present experimental conditions. However, additional testing under more variable environmental conditions should be performed before universal application of such models.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.598-607
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• 2016

This study was conducted to evaluate the amount of nitrogen (N) top dressing based on the normalized difference vegetation indices (NDVI) by ground based sensors for leaf perilla under the polyethylene house. Experimental design was the randomized complete block design for five N fertilization levels and conventional fertilization with 3 and 4 replications in Gumsan-gun and Milyang-si field, respectively. Dry weight (DW), concentration of N, and amount of N uptake by leaf perilla as well as NDVIs from sensors were measured monthly. Difference of growth characteristics among treatments in Gumsan field was wider than Milyang. SPAD-502 chlorophyll meter reading explained 43.4% of the variability in N content of leaves in Gumsan field at $150^{th}$ day after seedling (DAS) and 45.9% in Milyang at $239^{th}$ DAS. Indexes of red sensor (RNDVI) and amber sensor (ANDVI) at $172^{th}$ day after seedling (DAS) in Gumsan explained 50% and 57% of the variability in N content of leaves. RNDVI and ANDVI at $31^{th}$ DAS in Milyang explained 60% and 65% of the variability in DW of leaves. Based on the relationship between ANDVI and N application rate, ANDVI at $172^{th}$ DAS in Gumsan explained 57% of the variability in N application rate but non significant relationship in Milyang field. Average sufficiency index (SI) calculated from ratio of each measurement index per maximum index of ANDVI at $172^{th}$ DAS in Gumsan explained 73% of the variability in N application rate. Although the relationship between NDVIs and growth characteristics was various upon growing season, SI by NDVIs of ground based remote sensors at top dressing season was thought to be useful index for recommendation of N top dressing rate of leaf perilla.

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.196-203
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• 1999

To establish the best rice cultivating system in the aspects of environment-loving agriculture, the amounts and patterns of nitrogen leached in the paddy soil were investigated with 7 treatments; Recommendation(R), Farmer's usual practice(FUP), Straw compost+chemical fertilizers reduced(SCF), Fresh straw+recommendation(FSC), Fresh cow manure(FCM), Cow manure compost(CMC), and no fertilization as Control(C). And SCF, FCM and CMC were applied with same amounts of total nitrogen to R. The infiltrated water samples were collected in ceramic porous cups which were buried at 60cm depth from the top. Concentrations of nitrate-N in irrigated water were $1.3mg\;l^{-1}$ on rice transplanting season when nutrients began to elute from paddy soil, and $0.4mg\;l^{-1}$ after breaking off irrigation. But it was $4-6mg\;l^{-1}$ in rice growing period. The maximum concentration of nitrate-N in leachate was not more than $7mg\;l^{-1}$ during rice cultivation. The amounts of nitrogen leached in R, FUP, SCF, FSR, FCM, CMC and C were 59, 63, 25, 41, 24, 27, $17kg\;ha^{-1}y^{-1}$ respectively. Nitrogen leaching was decreased to about 30% by supplement of fresh rice straw(FSC) to R. Furthermore, it was possible to reduce to over 50% of nitrogen leaching by reducing chemical fertilizer application(CF), or by substituting of chemical fertilizers with fresh cow manure(FCM) or cow manure compost(CMC). In added organic fertilizer treatments, the amounts of infiltrated nitrogen were less $13-46kg\;ha^{-1}y^{-1}$ than that of input by irrigation. This experiment showed that nutrients leaching was minimized by substitution of chemical fertilizers with organic fertilizer or by application of straw with chemical fertilizers in rice paddy soil and rice cultivation with suitable fertilizer management can work as a purifier rather than contaminator of water.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.2
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• pp.15-23
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• 2021

This study was conducted to evaluate the field application of the developed recommendation system in organic rice (Oriza sativa L.) paddy and to investigate the mineral nitrogen content in soil and rice productivity. According to the developed system, hairy vetch (HV), rye+rapeseed oil cake (R+OC), rapeseed oil cake (OC) for only basal fertilization (OC-B), OC for split application (OC-S), pig manure compost (PMC), and chemical fertilizer (CHM) were applied to paddy soil at the rate of 107~133 kg N/ha. Results were followed, unhulled rice yield of OC-S (111%), OC-B (110), R+OC (106), HV (101), and PMC (96) were no significantly different with CHM (100). Also there was positive correlation (R²=0.803^*) between unhulled rice yield and cumulative inorganic N in soil. For nitrogen use efficiency of rice, OC-B, OC-S, and R+OC were not significantly different with CHM. In conclusions, the developed organic materials use recommendation system was effective for organic rice productivity. It could be useful for organic farmer to apply the organic materials use recommendation system for rice.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.212-216
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• 2012

BACKGROUND: Green manure and graminaceousmanure crops have several benefits, such as improving soil physical and chemical properties and utilizing excessive greenhouse nutrients that they have a potential to be a water pollutant source. METHODS AND RESULTS: The objective of this study was to investigate nitrogen (N) supplying capabilities of green manure and graminaceous manure crops for lettuce (Lactuca sativa L.) and Chinese cabbage (Brassica campestris L.) grown under greenhouse conditions. For this two leguminous manures (Crotalaria juncea (Cr.) and Sesbaniaexaltata (Se.)) and two graminaceous manures (Sorghum bicolor; Haussolgo(Ha.) and Sudangrass (Sg.)) in the greenhouse were grown, cut, and incorporated into the greenhouse soil before planting. Chemical nitrogen (N) fertilizer rate was estimated based on N recommendation for lettuce and Chinese cabbage. 100% of the N recommended rates (1N) were 70 kg N $ha^{-1}$ for lettuce and 60 kg N $ha^{-1}$ for Chinese cabbage and 50% of the N recommendation rates (0.5N) were 35 kg N $ha^{-1}$ for lettuce and 30 kg N $ha^{-1}$ for Chinese cabbage. Nitrogen treatments were control (0N), Cr., Se., Cr + 0.5 N, Se + 0.5 N, Ha + 0.5 N, Sg + 0.5 N, and N recommendation rate (1N). Incorporated N from green manure and graminaceous manure crops were 130, 116, 93, and 87 kg N $ha^{-1}$ for Cr., Se., Ha., and Sg., respectively. Lettuce and Chinese cabbage were grown after incorporated green manure crops into the greenhouse soil. There was no significant difference in lettuce and Chinese cabbage yields under N treatments except control (0 kg/ha). Nitrogen use efficiency (NUE)was from 44% to 73% and the highest NUE was under Se. treatment. Although yields were not statistically different under N treatments except control, actual yield increase ranged from 170 to 1,100 kg/ha for lettuce and ranged from 2,770 to 5,210 kg/ha for Chinese cabbage compared to yield under N recommendation rate. Estimated economic benefit from this would be higher approximately between \2,770,000 and \5,210,000/ha under N treatments except control than the N recommendation rate. CONCLUSION: These results suggest that incorporating green manure crops, such as Cr. and SeSe. into soil or adding 0.5 N after incorporation of them can be beneficial in many ways in that it increases economic return because of yield increase, reduces the use of chemical N, and decreases the negative environmental impact on water quality because excessive N in the greenhouse soil can be used by green manure crops during the fallow.