• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1118-1123
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• 2011

The changes of available silicate (Avail. $SiO_2$) contents in paddy soils (sandy loam) were assessed from data of the 41 years fertilization plots in which the continuous rice cropping experiment started in 1954 at the National Academy of Agricultural Science. The treatments were no fertilization (O), inorganic fertilization (NPK), inorganic fertilizer plus rice straw compost (NPK+C), inorganic fertilizer plus silicate fertilizer as a soil amendment (NPK+S), inorganic fertilizer plus rice straw compost and silicate fertilizer (NPK+CS) and inorganic fertilizer plus rice straw compost, silicate fertilizer and lime (NPK+CSL). Available silicate contents in NPK+S, NPK+CS and NPK in surface soil reached at the highest content ($255{\sim}330mg\;kg^{-1}$) after 41 years and then levelled off. Available silicate contents in subsurface soil (25~30 cm) were higher in NPK+C and NPK+S treatments than those in other treatments. Continuous application of silicate fertilizer affected significantly on the levels of available silicate in surface and subsurface soils. Silicate uptake of top rice was more increased by 98% in NPK+CS and NPK+CSL over NPK. Grain yield also increased by 37~47% in NPK+CS and NPK+CSL as compared to NPK. The combined applications of inorganic fertilizers with silicate as a soil amendment are recommended as the best fertilization practice for fertilizer use efficiency, enhancement of soil fertility status in the continuous rice cropping system in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.3
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• pp.216-222
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• 2013

Fertilizer management has the potential to promote the storage of carbon and nitrogen in agricultural soils and thus may contribute to crop sustainability and mitigation of global warming. In this study, the effects of fertilizer practices [no fertilizer (Control), chemical fertilizer (NPK), Compost, and chemical fertilizer plus compost] on soil total carbon (TC) and total nitrogen (TN) contents in inner soil profiles of paddy soil at 0-60 cm depth were examined by using long-term field experimental site at $42^{nd}$ years after installation. TC and TN concentrations of the treatments which included N input (NPK, Compost, NPK+Compost) in plow layer (0-15 cm) ranged from 19.0 to 26.4 g $kg^{-1}$ and 2.15 to 2.53 g $kg^{-1}$, respectively. Compared with control treatment, SOC (soil organic C) and TN concentrations were increased by 24.1 and 31.0%, 57.6 and 49.7%, and 72.2 and 54.5% for NPK, Compost, and NPK+Compost, respectively. However, long term fertilization significantly influenced TC concentration and pools to 30 cm depth. TC and TN pools for NPK, Compost, NPK+Compost in 0-30 cm depth ranged from 44.8 to 56.8 Mg $ha^{-1}$ and 5.78 to 6.49 Mg $ha^{-1}$, respectively. TC and TN pools were greater by 10.5 and 21.4%, 30.3 and 29.6%, and 39.9 and 36.3% in N input treatments (NPK, Compost, NPK+Compost) than in control treatment. These resulted from the formation and stability of aggregate in paddy soil with continuous mono rice cultivation. Therefore, fertilization practice could contribute to the storage of C and N in paddy soil, especially, organic amendments with chemical fertilizers may be alternative practices to sequester carbon and nitrogen in agricultural soil.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.641-647
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• 2015

Monitoring of soil fertility by long-term application of fertilizers is necessary to improve the fertility of soil and the productivity of crop. The objective of this study was conducted to investigate the changes of exchangeable Mg by continuous application of fertilizers from 1969 to 2014. The treatments were no fertilization (No fert.) and fertilization (NPK, NPK+C, NPK+S, and NPK+CS). The concentration of exchangeable Mg in No fert., NPK+C, and NPK+S treatments tended to increase from 1965 to 1975, but decrease gradually from 1976 to 1987, and increase again after 1988. Based on these, the changes of exchangeable Mg were divided into period I ('69 ~'75), period II ('76~'87), and period III ('88~'14). Especially, exchangeable Mg decreased in the period II. This was presumed that a significant amount of Mg from topsoil were leached into subsoil by break of plow pan and some of subsoil was incorporated into topsoil according to change of plowing depth by replacement of tillage machinery. It could be possible that exchangeable Mg in NPK, NPK+S, and NPK+CS was accumulated in the depth of 15~20 cm. For the period III, exchangeable Mg in No fert., NPK, NPK+C, NPK+S, and NPK+CS treatments increased at rates of 0.013, 0.018, 0.015, 0.023, and $0.024cmolckg^{-1}{\cdot}yr^{-1}$ respectively. Exchangeable Mg level in NPK+S was lower than the other treatments in the period I and period II, but higher than in the period III. This result was attributed to replacement of silicate fertilizer type from wollastonite (Mg 0.3%) to silicate fertilizer (Mg 3%). Also, exchangeable Mg level of No fert. treatment increased, which showed that Mg concentration of irrigated water had the greatest impact on Mg accumulation of soil. Recently, Mg level of irrigated water tended to increase, indicating that Mg concentration of water will affect greatly the concentration of exchangeable Mg of soil in the future. Like these, the changes of exchangeable Mg were greatly influenced by agricultural environment such as plowing depth, plow pan, content of fertilizer, and quality of irrigated water. Considering these agricultural environment, the proper management of soil is needed for the improvement of soil fertility and crop productivity.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.175-181
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• 2000

This study was carried out to investigate the change of soil physical properties in long-term fertilized paddy soils with a Fine silty family of Typic Halpaqueps (Pyeongtaeg series). Treatments fertilized consisted of no fertilizer, compost, NPK, NPK+compost for thirty one years and of NPK+silicate for seventeen years. Water stable aggregate and degree of aggregate stability, which were higher in surface-soil than sub-soil, were high in order of NPK + compost > NPK + silicate > compost > NPK > no fertilizer plot. The ratio of aggregate larger than 0.5mm was high at compost and silicate plots but that smaller than 0.5mm was high at no fertilizer and NPK plots. And this aggregate stability showed negative correlation with soil hardness and bulk density ; positive correlation with sedimentation volume of soils in water. Sedimentation volume of soils in water was a little higher in surface-soil than sub-soil and in wet soil than dry soil, respectively. Pore space ratio and water retention capacity of soils were the most increased by the application of compost and not affected by silicate as in cases of liquid limit and plastic limit. Ignition loss of soils was high in order of NPK + compost > compost > NPK + silicate > NPK > no fertilizer plot. And field shattering ratio of soil mass smaller than 25.4mm was relatively high in NPK + compost, compost, and silicate plots.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.3
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• pp.223-229
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• 2013

Sustainability index was calculated to determine the best management for rice productivity under long-term inorganic fertilizer management's practices. It is based on nutrient index, microbiological index and crop index related to sustainability as soil function. Indicators for calculating sustainability index were selected by the comparison of soil properties and rice response in paddy soil with fertilization. Total twenty two indicators were determined to assess nutrient index, microbiological index and crop index in order to compare the effect of different fertilization. The indices were applied to assess the sustainability with different inorganic fertilizer treatments such as control, N, NK, NP, NPK, NPK+Si, and NPK+Compost. The long-term application of compost with NPK was the highest sustainability index value because it increased nutrient index, microbial index and crop index. The use of chemical fertilizers resulted in poor soil microbial index and crop index, but the treatments like NP, NPK, and NPK+Si were maintained sustainability in paddy soil. These results indicate that application of organic and chemical fertilizer could be a good management to improve rice sustainability in paddy soil.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.2
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• pp.111-118
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• 2018

A field experiment was conducted to investigate the effect of long-term (21-year) fertilizer and compost treatments on the yield of red pepper and chemical properties in top-dong, Suwon. Six treatments were chosen for this work: No fertilization (No fert.), NPK fertilizers (NPK), NPK and compost (NPK+Compost), NP and compost (NP+Compost), NK and compost (NK+Compost), PK and compost (PK+Compost). The yield of red pepper for 21 years indicated the significant differences among the No fertilization, the PK+Compost, and other treatments. The relative yield index was 13% and 59% respectively, for the No fertilization and the PK+Compost if the average yield of red pepper for the NPK regards $20,048kg\;ha^{-1}$ as the yield index with 100%. Soil organic matter at the compost applied treatments significantly increased compared with the No fert. and the NPK. The average increase rates of soil organic matter by applying the compost ranged from 0.69 to $0.73g\;kg^{-1}\;yr^{-1}$. Available phosphate content in soil appeared the significant increase all treatments excluding the No fert. It is estimated that the available phosphate in soil was increased by $7.0mg\;kg^{-1}\;yr^{-1}$ by applying compost and $14.2mg\;kg^{-1}\;yr^{-1}$ by applying P fertilizer. Application of K fertilizer or the compost alone, the NPK, the NP+Compost, continuously caused soil K depletion whereas K fertilization plus the compost maintained at a constant level of exchangeable K. The results indicated that the addition of compost to NPK fertilizer is recommended for the maximum stable yield for red pepper and enhancement of organic matter though it is also needed for adjusting of P and K fertilization.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.325-329
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• 2001

Soil enzyme and microbial activities are affected by fertilizer and compost applications and can be used as sensitive indicators of ecological stability. Microbial population and soil enzymes viz., dehydrogenase, urease, acid phosphatase and aryl-sulphatase were determined in the long-term fertilizer and compost applied paddy soil. Soil samples were collected from the four treatments (control, compost, NPK and compost+NPK). Long-term NPK+compost application significantly increased activities of urease, dehydrogenase and acid phosphatase than all other treatments. The compost application enhanced activities of urease, dehydrogenase and acid phosphatase than the NPK application. However, arylsulfatase activity was not significantly different between compost and fertilizer application. The highest microbial population was recorded in the NPK+compost treatment. The compost application also resulted in higher microbial population than the NPK application. The above results indicate that ecological stability could be maintained by application of compost alone or with NPK.

• Journal of Forest and Environmental Science
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• v.31 no.4
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• pp.303-311
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• 2015

This study aimed to assess the effects of tree manures in comparison with NPK fertilizer on growth of Acacia senegal seedlings. It was conducted in the nursery of the Faculty of Forestry, University of Khartoum, Shambat (Lat.: $15^{\circ}$ 39' 387" N and Long.: $32^{\circ}$ 30' 871" E), during August 2008 and January 2009. The growing media were prepared by mixing ground foliage of trees with sandy soil (weight/volume) as follows, Albizia lebbeck (AL): 25 g, 50 g and 75 g; Azadirachta indica (AZ): 25 g, 50 g and 75 g; Khaya senegalensis (KH): 25 g, 50 g and 75 g; NPK fertilizer: 30 g per seedling. Albizia lebbeck and Azadirachta indica manures and NPK fertilizer have stimulated the Acacia senegal seed germination percentage in comparison with the control, with respective values of 89, 82.7, 81 and 71%. Khaya senegalensis manure has suppressed the Acacia senegal seed germination percentage with a value of only 49%. Effects of treatments on the seedlings growth parameters varied in the following percentages, in comparison to the control, shoot height: AZ 62.9%, AL 46%, KH 9.9% and NPK 27.8%; root length: AZ 25.8%, AL 31.5%, KH 30.6% and NPK 4.4%; diameter: AZ 75.2%, AL 37.1%, KH 34.3% and NPK 20%; Shoot biomass: AZ 319%, AL 195.2%, KH 57.1% and NPK 42.9%; root biomass: AZ 288.9%, AL 116.7%, KH 55.6% and NPK 16.7%%;. Thus, the effectiveness of the used substrates on the growth performance of Acacia senegal seedlings occurred in the following descending order: Azadirachta indica> Albizia lebbeck>Khaya senegalensis>NPK fertilizer. These results assert clearly the ameliorative and fertilizing characteristics of tree manures that can be reliably used for raising seedlings stocks in the nurseries.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.819-825
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• 2016

Monitoring of soil fertility and crop productivity in long-term application of silicate fertilizers is necessary to use fertilizers efficiently. This study was conducted to investigate effects of continuous application of silicate fertilizer for rice cultivation from 1969 to 2014. The treatments were no silicate fertilizer treatments (N, NC, NPK, and NPKC) and silicate fertilizer treatments (N+S, NC+S, NPK+S, and NPKC+S). The 46-yr input of $2\;ton\;ha^{-1}yr^{-1}$ of silicate fertilizer increased pH 0.6 ~ 1.1 and exchangeable Ca $2.0{\sim}2.4cmol_c\;kg^{-1}$ in silicate fertilizer treatments (N+S, NC+S, NPK+S, and NPKC+S) compared with no silicate fertilizer treatments (N, NC, NPK, and NPKC) because silicate fertilizer included Ca component. Also, available silicate concentrations of silicate fertilizer treatments (N+S, NC+S, NPK+S, and NPKC+S) increased $169mg\;kg^{-1}$ compared to no silicate fertilizer treatments. In Period II ('90~'14), the mean annual Si field balance varied from 62 to $175kg\;ha^{-1}yr^{-1}$ in silicate fertilizer treatments, indicating continuous accumulation of soil Si. Silicon uptake and grain yield of rice had greater differences between N treatment and N+S treatment than other treatments. This showed that the application of silicate fertilizer had greater effect in nutrient-poor soils than in proper nutrient soils. Thus the application of silicate fertilizer led to improvement the fertility of soil and increasement of rice production for the lack of soil nutrients.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.487-493
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• 2013

The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.