Application Of Silicate Fertilizer Research Articles

Increase of soil organic carbon stock by iron slag-based silicate fertilizer application in paddy soils

Silicate fertilizer derived from iron slag (hereafter, silicate fertilizer) as a soil amendment has been added to Korean and Japanese rice paddies to improve soil pH and supply nutrients to the crop. However, the consequences of silicate fertilizer application to soil organic carbon (SOC) stocks remain unclear. Hypothetically, silicate fertilizer might deplete SOC by increasing soil pH and stimulating microbial activity or increase SOC by improving rice productivity and biomass. To investigate this, we first quantified the relationship between plant-available silicate (SiO2) and soil organic matter concentrations using national soil survey data. We found a highly positive correlation between the two parameters, suggesting that long-term silicate fertilizer application might promote SOC sequestration. We then examined the effect of silicate fertilizer and lime (CaCO3) addition on soil respiration for 30 days under flooded conditions. Both materials increase soil pH but affect soil respiration in different ways: respiration increased significantly with lime but decreased significantly with silicate fertilizer application. This demonstrates that silicate fertilizer simultaneously improves pH while minimizing C loss through soil respiration. Finally, in a field study spanning two years, we ascertained the impact of silicate fertilizer (1.5 Mg ha-1) on annual SOC stock changes under rice cropping. Silicate fertilizer application increased net primary production (NPP) of rice plants by around 20% over control plots that did not receive silicate but decreased respired C loss by 16–20%. As a result, silicate fertilizer application increased the SOC stock by 0.96–1.1 Mg C ha−1 year−1 over the control. Our findings show that iron slag-based silicate fertilizer can promote C sequestration in soil organic matter while simultaneously improving soil properties and rice productivity.

The effect of nitrogen, sulfur and silicate fertilizer application on growth, yield, and biochemical content of vegetable soybean pod (Glycine max L. Merr.)

Optimized fertilizer management, focusing on nitrogen, sulfur, and silica, plays a crucial role in agriculture production. This study aimed to investigate the effects of administering sulfur and silica on the growth, production yield, and biochemical contents of vegetable soybean. The investigation was conducted in factorial randomized block design with two factors and three replications. The first factor was the nitrogen (46% N) fertilizer dosage (N1 = 50 kg/ha and N2 = 100 kg/ha), while the second variable was the dosage with the following sulfur-silica soluble compound (2.3% S – 10% Si) fertilizer ratios (P0 = 0 ml/L (control), P1 = 1 ml/L (23 mg/L S and 100 mg/L Si), P2 = 1.33 ml/L (30,7 mg/L S and 133 mg/L Si), and P3 = 2 ml/L (46 mg/L S and 200 mg/L Si). The results indicated that applying 2 ml/L S-Si fertilizer along with 100 kg/ha of nitrogen can lead to the most favorable results in number of branches, number of leaves, number of pods, pod weight per plant, weight of 100 seeds and plant biomass weight. The fertilizer dose comprising of 50 kg/ha of N and 9.2-40 mg/plant of S-Si clearly demonstrated the highest protein content, measuring 110.6 mg/g. S-Si fertilizer dosages, exhibiting a linear escalation in the 11S/7S globulin ratio within vegetable soybean seeds. The peak 11S/7S ratio was observed in the treatment of 100 kg/ha of N - 2 ml/L of S-Si. The study results indicate that a combination of nitrogen fertilizer and sulfur-silicon yields the best vegetable soybean pod yield, improving soybean protein nutritional quality. Therefore, sulfur and silica treatments should be standardized in vegetable soybean management

Impact of silicate fertilizer on soil properties and yield of bread wheat in Nitisols of tropical environment

PurposeSoil acidity and depletion of essential plant nutrients are among the major abiotic stresses that constrained wheat productivity in Ethiopia. Silicates and silicate by-products can be used as alternative source for amendment of soil acidity and improvement of crop yields. Surface application of water-soluble silicate fertilizer alone and the integrated application with full does of recommended N and P from mineral fertilizers can reduce the extent of soil acidity and improve phosphorous availability in the soil, soil pH and exchangeable acidity and can enhance the yield attributes and yield of bread wheat. A field experiment was conducted under rain-fed condition from July to December of 2020 to evaluate the role of soil and foliar application of water-soluble silicate fertilizer without and with reduced or full doses of recommended nitrogen (N) and phosphorus (P) (RNP) from mineral fertilizers on soils chemical attributes, yield components and yield of bread wheat sown under moderately to strongly acidic condition in southeastern Ethiopia. MethodsThe experiment comprised sole silicate (40 kg + 18 L/ha−1), and its integration with full dose of RNP (92–30 kg N–P ha−1), three quarters dose of RNP (69–23 kg N–P ha−1) and half dose of RNP (46–15 kg N–P ha−1) from mineral fertilizers. Full dose of RNP from mineral fertilizers and a negative control with no silicate and mineral fertilizer inputs included as controls, resulting in a total of six treatments. The experiment was laid out in randomized complete block design, replicated three times. ResultsThe combined application of silicate with mineral fertilizers significantly influenced soil properties, yield attributes and yield of bread wheat. Integrated applications of silicate fertilizers and full dose of RNP increased grain yield, biomass yield, and available soil P by 108, 115, and 23 % respectively relative to untreated soil. ConclusionsIntegration of silicate with mineral fertilizers can be considered as a viable and alternative option for acid soils amendment. Generally, the result of the current study revealed that combined application of water soluble granular and liquid silicate at the rate of (40 kg + 18 L)/ha with full dose of recommended nitrogen (92 kg ha−1) and phosphorus (30 kg ha−1) significantly reduced exchangeable acidity, tended to increase soil reaction, increased available soil phosphorus content and boosted yield of bread wheat compared to their sole applications. Thus, application of water-soluble silicate fertilizer with recommended rate of nitrogen and phosphorus is better in enhancing plant nutrition and yield of bread wheat in the highlands of Ethiopia and other similar agro-ecologies.

Physiological resistance responses of rice plant (Oryza sativa) provided with silicate fertilizer to sheath blight disease (Rhizoctonia solani)

Abstract. Azizah R, Rachmawati D. 2023. Physiological resistance responses of rice plant (Oryza sativa) provided with silicate fertilizer to sheath blight disease (Rhizoctonia solani). Biodiversitas 24: 3785-3795. Sheath blight disease that is caused by the fungus Rhizoctonia solani Kühn generally leads to the reduction of rice yields. The application of silicate fertilizers can increase the resistance to pathogens. This research aimed to determine the effect of silicate fertilizer application on the physiological resistance responses of rice plants to R. solani, the primary pathogen responsible for rice sheath blight. This study used three rice cultivars with different resistance levels to sheath blight, including Pandan Wangi (resistant), Cisadane (susceptible), and IR64 (moderately resistant), which were treated with three doses of silicate fertilizer 0 kg ha-1, 200 kg ha-1 and 400 kg ha-1 with sheath blight inoculation and without inoculation. The results showed that Pandan Wangi provided with 200 kg ha-1 silicate fertilizer produced the highest reduction in the percentage of relative lesion height (RLH), and the application of 400 kg ha-1 silicate fertilizer had a greater positive effect of reducing the lesion in Cisadane and IR64. In susceptible and moderately resistant cultivars, Cisadane and IR64, higher doses of silicate fertilizer have a better effect on strengthening plant tissue during inoculation treatments. The application of 400 kg ha-1 silicate fertilizer without inoculation significantly affected relative water content. In the moderately resistant cultivar IR64, the silicate fertilizer played a role in the physiological response by strengthening the plant tissue, as indicated by the increasing lignin content, sclerenchyma and cuticle thickness.

Growth and physiological response of rice ‘Inpari 35’ under salinity stress and application of silicate fertilizer

Rice is an important staple food in Indonesia. Crop areas can be expanded to boost productivity by utilizing marginal lands, which are saline. This study aims to study the growth and physiological response of rice ‘Inpari 35’ to the application of silicate fertilizer under salinity stress conditions. This study used a completely randomized design (CRD) with two factors. The first factor is the difference in NaCl salt concentration consisting of N0: 0 mM; N1: 37.5 mM; N2: 50 mM, while the second factor is the difference in the concentration of silicate fertilizer (CaSiO3) consisting of S0: 0 mM; S1: 1 mM and S2: 2 mM. Each treatment combination was repeated three times. Observed data were analyzed by analysis of variance (ANOVA). A significant difference between treatments is continued with Duncan's multiple distance test at a 95% confidence level. The results showed that NaCl treatment significantly (p<0.05) inhibited the growth of rice ‘Inpari 35’, which was indicated by a decrease in the plant height and number of leaves. The NaCl treatment caused a reduction in the levels of chlorophyll, carotenoids, proline, membrane stability index (MSI), and relative water content (RWC). The interaction between NaCl treatment and CaSiO3 showed significant differences in physiological parameters by increasing the levels of chlorophyll, carotenoid, proline, membrane stability index, and relative water content.

Creating new value of blast furnace slag as soil amendment to mitigate methane emission and improve rice cropping environments

Blast furnace slag (BFS), a by-product of iron making, has been utilized as silicate fertilizer in Korean and Japanese rice paddy. Silicate fertilizer, which has high contents of active iron and manganese as electron acceptor, was newly known to suppress methane (CH4) emission in flooded rice paddies, but the effect of its long-term application on rice cropping environment is still debatable. To evaluate the effect of silicate fertilization on suppressing CH4 emissions, the changes of CH4 index, indicating the ratio (%) of seasonal CH4 flux at the silicate fertilization treatment to that at the control, were generalized using the global investigation data (42 observations from 8 fields in Bangladesh, China, and Korea). Seasonal CH4 fluxes significantly decreased with increasing silicate fertilization levels. In CH4 index changes, 1.5 Mg ha−1 of silicate fertilizer application (the recommended level of rice cultivation in Korea) decreased by 15% of seasonal CH4 fluxes. Rice grain yield highly increased with increasing silicate fertilization rates and maximized at approximately 4 Mg ha−1 with 18% higher than no-silicate fertilization due to overall improvement of soil properties. To evaluate the long-term silicate fertilization effect on rice cropping environments, silicate (1.5 Mg ha−1 year−1) and non-silicate fertilization treatments were installed in a typical temperate-monsoon climate paddy field in South Korea in 1990. Periodic silicate fertilization significantly increased rice grain productivity by an average of 14% over the control for the last 28 years. This fertilization evidently improved rice quality without changes in chemical quality. Consecutive silicate fertilization effectively improved soil physical and chemical properties but did not increase any acid extractable heavy metal concentration in soil. In conclusion, BFS as silicate fertilizer could be a beneficial amendment to mitigate CH4 emission in the rice paddy and improve soil properties and rice productivity and quality without hazardous material accumulation.

Magnesium and silicon fertilizer application to promote rice growth and production

The global demand for rice continues to increase due to population growth. In Indonesia, various innovations have been implemented for improving rice production, while magnesium silicate fertilizer application is still limited. The study was undertaken to investigate the effect of Mg and Si (MgSi Fert) on rice growth and productivity. This study was conducted at Luhur Jaya Village, Cipanas District, Lebak Regency, Banten Province in a rainy season. A randomized complete block design with ten treatments and three replications was set. The treatment was MgSi Fert with multiple dosages. Results showed that NPK fertilizer combined with 100 kg ha−1 MgSi fertilizer gave the highest yield. Based on the quadratic equation y = - 0.1301x2 + 28.812x + 5,474.2, it was known that highest slope on the equation was reached at dosage less than 150 kg ha−1 of MgSi Fert. The optimum dosage of MgSi Fert for Ciherang rice variety was achieved at 110 kg ha−1 with yield as 7.07 t ha−1. This present study showed that MgSi Fert application improved rice growth and yield.

Silicate fertilizer application reduces soil greenhouse gas emissions in a Moso bamboo forest

Silicate fertilizer application in croplands is effective in mitigating soil methane (CH4) emissions and increasing rice yield. However, the effects of silicate fertilizer on soil greenhouse gas (GHG) emissions in Moso bamboo forests, and the underlying mechanisms are poorly understood. In the present study, a two-year field experiment was conducted to investigate the effect of silicate fertilizer rates (0 (CK), 0.225 and 1.125 Mg ha−1) on soil GHG emissions in a Moso bamboo forest. The results showed that silicate fertilizer application significantly reduced soil CO2 and N2O emissions, and increased soil CH4 uptakes. Compared to the CK treatments, the cumulative soil CO2 emission fluxes decreased by 29.6% and 32.5%, and the cumulative soil N2O emission fluxes decrease by 41.9% and 48.3%, the CH4 uptake fluxes increased by 13.5% and 32.4% in the 0.225 and 1.125 Mg ha−1 treatments, respectively. The soil GHG emissions were significantly positively related to soil temperature (P < 0.05), but negatively related to soil moisture; however, this relationship was not observed between CH4 uptake fluxes and moisture in CK treatment. Soil CO2 emission and CH4 uptake were significantly positively related with water-soluble organic C (WSOC) and microbial biomass C (MBC) concentrations in all treatments (P < 0.05). Soil N2O emissions were significantly positively related to MBC, NH4+-N, NO3−-N, and microbial biomass N (MBN) concentrations in all treatments (P < 0.05), but not with WSOC concentration. Structural equation modeling showed that application of silicate fertilizer directly reduced soil GHG emission by decreasing the labile C and N pools, and indirectly by influencing the soil physicochemical properties. Our findings suggest that silicate fertilizer can be an effective tool in combatting climate change by reducing soil GHG emissions in Moso bamboo forests.

Pemberian Pupuk Silikat dan Pupuk Kandang Terhadap Pertumbuhan, Kadar Brix, dan Hasil Tanaman Sorgum (Sorghum bicolor (L.) Moench)

Abstract: Research on the application of silicate fertilizer and manure to growth, brix level, and yield of sorghum (Sorghum bicolor (L.) Moench) was investigated to find ways to increase sorghum productivity in the dry land. The research method used was an experimental method that was set in a randomized block design consisting of 9 treatments namely control (Si0P0), without silicate and manure, 5 tones/ha (Si0P5), without silicate and manure 10 tones/ha (Si0P10), silicate 100 kg/ha and without manure (Si100P0), silicate 100 kg/ha and manure 5 tones/ha (Si100P5), silicate 100 kg/ha and manure 10 tones/ha (Si100P10), silicate 200 kg/ha and without manure (Si200P0), silicate 200 kg/ha and manure 5 tones/ha (Si200P5), and silicate 200 kg/ha and manure 10 tones/ha (Si200P10). Each treatment was replicated 3 times and the size of the plot was 6x6 m2. The results indicated that the application of silicate fertilizer and manure could significantly increase yield and brix levels. Application of silicate fertilizer of 200 kg/ha and manure 5 tonnes/ha gave higher results for the production of sorghum was 6056 kg/ha. However, the growth of sorghum was not affected significantly to the growth of sorghum plants. Keywords: Silicate Fertilizer (Si); Manure; Sorghum Plant

The potential of silicate fertilizer for salinity stress alleviation on red rice (Oryza sativa L. ‘Sembada Merah’)

Climate change causes an increase in soil salinity, hence reduce rice growth and productivity. The application of silicate fertilizer as a source of silicon (Si) can be encouraged to enhance the rice tolerance against biotic and abiotic stresses. This study aimed to analyze the potential of silicate fertilizer to alleviate the salinity stress on red rice. A pot experiments was conducted to observe the physiological and biochemical aspects. Rice seedlings were treated with three doses of rice husk ash/RHA (0, 4, and 8 tons ha-1), and three levels of salinity stress, namely control (0 dS m-1), low (3 dS m-1), moderate (7 dS m-1), and high (10 dS m-1). The observed parameters were plant height, number of tillers, plant biomass, activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT), levels of chlorophyll, carotenoid and proline. The results showed the growth of red rice ‘Sembada Merah’ was inhibited by moderate and high salinity stress as indicated by a decrease in plant height, number of tillers and plant biomass. Photosynthetic pigment chlorophyll and carotenoid levels decreased with the increasing salinity stress. RHA application increased SOD activity as a response to enhance salinity stress tolerance. At doses of 4 t ha-1, RHA could maintain rice growth up to moderate salinity stress.

Taxonomic and functional responses of soil microbial communities to slag-based fertilizer amendment in rice cropping systems

The effective utilization of slag-based Silicon fertilizer (silicate fertilizer) in agriculture to improve crop productivity and to mitigate environmental consequences turns it into a high value added product in sustainable agriculture. Despite the integral role of soil microbiome in agricultural production and virtually all ecosystem processes, our understanding of the microbial role in ecosystem functions and agricultural productivity in response to the silicate fertilizer amendment is, however, elusive. In this study, using 16S rRNA gene and ITS amplicon illumina sequencing and a functional gene microarray, i.e., GeoChip 5, we report for the first time the responses of soil microbes and their functions to the silicate fertilizer amendment in two different geographic races of Oryza sativa var. Japonica (Japonica rice) and var. Indica (Indica rice). The silicate fertilizer significantly increased soil pH, photosynthesis rate, nutrient (i.e., C, Si, Fe, P) availability and crop productivity, but decreased N availability and CH4 and N2O emissions. Moreover, the silicate fertilizer application significantly altered soil bacterial and fungal community composition and increased abundance of functional genes involved in labile C degradation, C and N fixation, phosphorus utilization, CH4 oxidation, and metal detoxification, whereas those involve in CH4 production and denitrification were decreased. The changes in the taxonomic and functional structure of microbial communities by the silicate fertilizer were mostly regulated by soil pH, plant photosynthesis, and nutrient availability. This study provides novel insights into our understanding of microbial functional processes in response to the silicate fertilizer amendment in rice cropping systems and has important implications for sustainable rice production.

Improvement of Tomato Seedling Quality under Low Temperature by Application of Silicate Fertilizer

The object of this study was to improve tomato seedling quality in low temperature(below 7, 10oC during night time or daily mean air temperature was 18oC) by application of silicate fertilizer. Six different silicate fertilizer concentrations (8, 16, 32, 64, 128, and 256mM) or water as the control w...

Liming an acid soil treated with diverse silicon sources: Effects on silicon uptake by sugarcane (Saccharum spp. hybrids)

ABSTRACTHighly weathered soils are typically acid, with low plant-available silicon (Si), and may also be high in soluble aluminum (Al). We tested whether pre-liming an acid soil prior to silicate fertilizer application improved Si uptake by sugarcane (Saccharum spp. hybrids), feasibly through elimination of reactive Al. Three trials with potted sugarcane were grown in an acid soil. Treatments included 11 different Si sources and 1- or 3-month pre-liming periods. Soil and plant tissue Si content and yield were determined. Pre-liming for a 1- or 3-month period did not increase plant Si uptake and reduced available soil Si throughout. Alkaline Si sources produced significantly more plant-available Si and greater plant uptake than non-alkaline sources. Silicon and lime treatments did not significantly increase yield. We conclude that pre-liming an acid soil before Si application is unlikely to significantly improve Si uptake by sugarcane.

Long-term Application Effect of Silicate Fertilizer on Soil Silicate Storage and Rice Yield

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-1yr-1 of silicate fertilizer increased pH 0.6 ~ 1.1 and exchangeable Ca 2.0~2.4 cmolc kg-1in 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 169 mg kg-1 compared to no silicate fertilizer treatments. In Period II (’90~’14), the mean annual Si field balance varied from 62 to 175 kg ha-1yr-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.

Status and Changes in Chemical Properties of Paddy Soil in Gangwon Province

The chemical properties of paddy fields in Gangwon province were monitored every 4 years from 2003 to 2015 in order to provide basic information for soil fertility management of paddy fields. In 2015, the soil chemical properties of paddy fields were 5.9 in pH, <TEX>$22g\;kg^{-1}$</TEX> in organic matter (OM), and <TEX>$123mg\;kg^{-1}$</TEX> in available (Avail.) phosphate <TEX>$P_2O_5$</TEX>. Exchangeable (Exch.) potassium (K), calcium (Ca) and magnesium (Mg) were 0.39, 4.8 and <TEX>$0.9cmolc\;kg^{-1}$</TEX>, respectively, and Avail. <TEX>$SiO_2$</TEX> was <TEX>$170mg\;kg^{-1}$</TEX>. In the long-term analysis, the contents of Avail. <TEX>$SiO_2$</TEX>, Exch. K and pH of paddy soils showed increasing tendency. However, Avail. <TEX>$P_2O_5$</TEX>, Exch. Ca and Mg tended to decrease, and there were no significant changes in the contents of OM. Soil OM, Avail. <TEX>$P_2O_5$</TEX> and <TEX>$SiO_2$</TEX> were not different among the different topographical sampling sites. However, the mean value of Exch. K and Ca were different among the different topographical sampling sites, and exceeded optimal values in the fluvio-marine plains. Different soil texture resulted in different soil pH, while no difference for OM, Avail. <TEX>$P_2O_5$</TEX> and <TEX>$SiO_2$</TEX>. Paddy soil samples within appropriate pH range increased from 65% in 2003 to 77% in 2007, 68% in 2011, and 71% in 2015. In case of Avail. <TEX>$SiO_2$</TEX>, soil samples within appropriate range increased from 20% in 2003, to 37% in 2007, 29% in 2011, and 45% in 2015. Meanwhile, Cd and Pb were distributed to less than 5% of soil pollution standards. Cu, As and Zn were distributed to less than 10%, 15% and 20%, respectively. Therefore, paddy soil in Gangwon Province was judged to be safe. As a result, paddy fields with more or less in nutrient level need to be fertilized based on the soil analysis. And the application of silicate fertilizer is strongly recommended to those of paddy fields in need. In addition, soil management including the cultivation of green manure crop or application of rice straw is necessary to increase the organic matter content of paddy soil.

Status and Changes in Chemical Properties of Paddy Soil in Gyeonggi Province

The chemical properties of paddy fields in Gyeonggi province were monitored every 4 years from 1999 to 2015 in order to provide basic information for soil fertility management of paddy fields. In 2015, the soil chemical properties of paddy fields were 5.9 in pH, <TEX>$23g\;kg^{-1}$</TEX> in organic matter (OM), and <TEX>$84mg\;kg^{-1}$</TEX> in available phosphate (Avail. <TEX>$P_2O_5$</TEX>). Exchangeable (Exch.) potassium (K), calcium (Ca) and magnesium (Mg) were 0.30, 5.1 and <TEX>$1.3cmol_ckg^{-1}$</TEX>, respectively, and available silicate (Avail. <TEX>$SiO_2$</TEX>) was <TEX>$129mg\;kg^{-1}$</TEX>. In the long-term analysis, the contents of Avail. <TEX>$SiO_2$</TEX>, Exch. Ca and pH of paddy soils showed increasing tendency. However, Avail. <TEX>$P_2O_5$</TEX> and Exch. K tended to decrease, and there were no significant changes in the contents of OM and Exch. Mg. Paddy soil within appropriate pH range increased from 44% in 1999 to 76% in 2003, 84% in 2007, 63% in 2011, and 80% in 2015. But soil within appropriate range of Exch. Ca tended to decrease, showing 36% in 1999, 42% in 2003, 38% in 2007, 37% in 2011 and 32% in 2015. In case of Avail. <TEX>$SiO_2$</TEX>, soil within appropriate range increased from 14% in 1999 to 17% in 2003, 18% in 2007, 16% in 2011, and 31% in 2015. As a result, paddy fields with less in nutrient level need to be more fertilized based on soil analysis. And the application of silicate fertilizer is strongly recommended to those of paddy fields in need. Also soil management such as the cultivation of green manure crop or application of rice straw will be necessary to increase the organic matter content of paddy soil.

Effects of Granular Silicate on Watermelon (Citrullus lanatus var. lanatus) Growth, Yield, and Characteristics of Soil Under Greenhouse

The objective of this study was to determine the effects of granular type of silicate fertilizer on watermelon growth, yield, and characteristics of soil in the greenhouse. Four different levels of silicate fertilizer, 0(control), 600, 1,200, 1,800 kg ha -1 were applied for experiment. The silicate fertilizer was applied as a basal fertilization before transplanting watermelon. Compost and basal fertilizers were applied based on the standard fertilizer recommendation rate with soil testing. All of the recommended P₂O 5 and 50% of N and K₂O were applied as a basal fertilization. The N and K₂O as additional fertilization was split-applied twice by fertigation method. Watermelon (Citrullus lanatus Thunb.) cultivar was ‘Sam-Bok-KKuol and main stem was from rootstock (bottle gourd: Lagenaria leucantha Standl.) ‘Bul-Ro-Jang-Sang’. The watermelon was transplanted on April, 15. Soil chemical properties, such as soil pH, EC, available phosphate and exchangeable K, Mg, and available SiO₂ levels increased compared to the control, while EC was similar and the concentrations of soil organic matter decreased. Physical properties of soils, such as soil bulk density and porosity were not different among treatments. The growth characteristics of watermelon, such as stem diameter, fresh and dry weight of watermelon at harvest were thicker and heavier for silicate treatment than the control, while number of node was shorter than the control. Merchantable watermelon increased by 3-5% compared to the control and sugar content was 0.4 to 0.7 °Brix higher than the control. These results suggest that silicate fertilizer application in the greenhouse can improve some chemical properties of soils and watermelon stem diameter and dry weight, which are contributed to watermelon quality and marketable watermelon production.

규산질비료가 시설재배지 토양특성과 고추수량에 미치는 영향

Abstract BACKGROUND: This study was conducted to investigate effects of silicate fertilizer application on red pepper (Capsicum annuum L.) productivity with improving soil chemistry under plastic film house in paddy field. METHODS AND RESULTS: The silicate fertilizer was applied as 0, 100, 200, and 300 kg/10a as basal dressing before transplanting pepper plant seedlings. Cultivar of the pepper plant was Cheon-Ha-Dae-Se. Amounts of inorganic fertilizer applied as N-P 2 O 5 -K 2 O = 19.0-6.4-10.1 kg/10a was estimated depending on soil test values. After applying 50% of nitrogen, 100% of phosphorus, and 60% of potassium fertilizers as basal dressing, the seedlings of pepper plant were transplanted. The rests of nitrogen and potassium fertilizers were applied as side-dressing after the first, second, and fourth harvests of red pepper. When comparing selected chemical properties of soils between before transplanting and after final(the fifth) harvest, soil pH, available P 2 O 5 , and exchangeable Ca

Integrated effects of organic, inorganic and biological amendments on methane emission, soil quality and rice productivity in irrigated paddy ecosystem of Bangladesh: field study of two consecutive rice growing seasons

Effects of different soil amendments were investigated on methane (CH4) emission, soil quality parameters and rice productivity in irrigated paddy field of Bangladesh. The experiment was laid out in a randomized complete block design with five treatments and three replications. The experimental treatments were urea (220 kg ha−1) + rice straw compost (2 t ha−1) as a control, urea (170 kg ha−1) + rice straw compost (2 t ha−1) + silicate fertilizer, urea (170 kg ha−1) + sesbania biomass (2 t ha−1 ) + silicate fertilizer, urea (170 kg ha−1) + azolla biomass (2 t ha−1) + cyanobacterial mixture 15 kg ha−1 silicate fertilizer, urea (170 kg ha−1) + cattle manure compost (2 t ha−1) + silicate fertilizer. The average of two growing seasons CH4 flux 132 kg ha−1 was recorded from the conventional urea (220 kg ha−1) with rice straw compost incorporated field plot followed by 126.7 (4 % reduction), 130.7 (1.5 % reduction), 116 (12 % reduction) and 126 (5 % reduction) kg CH4 flux ha−1 respectively, with rice straw compost, sesbania biomass, azolla anabaena and cattle manure compost in combination urea and silicate fertilizer applied plots. Rice grain yield was increased by 15 % and 10 % over the control (4.95 Mg ha−1) with silicate plus composted cattle manure and silicate plus azolla anabaena, respectively. Soil quality parameters such as soil organic carbon, total nitrogen, microbial biomass carbon, soil redox status and cations exchange capacity were improved with the added organic materials and azolla biofertilizer amendments with silicate slag and optimum urea application (170 kg ha−1) in paddy field. Integrated application of silicate fertilizer, well composted organic manures and azolla biofertilizer could be an effective strategy to minimize the use of conventional urea fertilizer, reducing CH4 emissions, improving soil quality parameters and increasing rice productivity in subtropical countries like Bangladesh.

논토양에서 규산질비료 시용이 토양 환경에 미치는 영향

Application of silicate fertilizers is typically practiced with several year’s interval to amend soil quality and improve rice productivity at the paddy field in Korea. Most of silicate fertilizers applied in Korea is slag-originated silicate fertilizer. Some water soluble silicate fertilizers are manufactured and commercially available. The objective of this study was to assess changes of soil chemical properties in paddy field by applying slag-originated silicate fertilizer and water soluble silicate fertilizer. Field experiment was conducted on a silt loam paddy soil, where four levels of each silicate fertilizer were applied in soil at the rate of 0, 1, 2, 4 times of the recommended levels. Application of slag-originated silicate fertilizer increased soil pH, while no significant pH increase occurred with the treatment of water soluble silicate fertilizers. Soil pH increased 0.4∼0.5 with the 1 time of recommended level of slag-originated silicate fertilizer. Available SiO2 contents also significantly increased with the treatment of slag-originated silicate fertilizer at 15 and 35 days after treatment, while decreased after 60 days after treatment possibly due to rice uptake. Exchangeable Ca, Mg and available phosphate contents in soil increased with application of slag-originated silicate fertilizer, while a little increases for them were shown with the application of soluble silicate fertilizer. SiO2/N ratios in rice straw for 1 time of recommended level of slag-originated silicate fertilizer was 11.5, while that of control was 8.4, which was much lower value. Throughout this study, soil application of slag-originated silicate fertilizer enhanced soil chemical properties, while water soluble silicate fertilizer application in soil needs further study resulting in a little effects on soil property.