It has been debated whether long-term stability of heavy metals is altered by incorporation of steel slag and similar materials into soil. This slag which contains the phosphorus in the form of silicophosphates is ground to a fine powder. Rice plants were harvested at maturity, and separated into stem, leaf, and grain, and then washed thoroughly with distilled water. Like the old basic slag our grade of steel works slag called Super Slag Basic is principally a lime based material which has absorbed the . The first factor influencing plant available–silicon concentration may be associated with the different weather conditions in the two seasons. The second factor may be related to the residual effect of steel slag applied in the first season. Figure 15 shows the changes in Na content of pore water in 2012. Did you know that all silicate fertilizer used in Korea is made from POSCO slag? Slag, which is a by-product of ironmaking at steelworks, contains 25-30% of soluble silicic acid. Yes The enhanced soil pH and soil available Si content may contribute to a decrease the available concentration of heavy metals by reducing metal mobility and bonding metals into more stable fractions. Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. https://doi.org/10.1371/journal.pone.0168163.g003. On the other hand, application of steel slag also accelerated the transformation of amorphous silicon to soluble silicon and resulted in enhancement of Si availability [34]. This point of view might explain why continuous application of slag at a huge rate (e.g., 2000 mg plant-available SiO2 per kg soil) significantly depressed further dissolution of Si from steel slag. 65, No. https://doi.org/10.1371/journal.pone.0168163.g002. First, steel slag fertilizer was incorporated well with 5.0 kg soil in each plastic pot. Steel LD slag can also be used in fertilizers for agricultural applications (Das et al., 2007). The range of Na content was close to that observed with the column test. The chemical composition of CaO, SiO2, and MgO in steel slag was the same as that of the raw inorganic fertilizer material, in terms of composition and also contained e ective components such as FeO, MnO, and P2O5 [18,19]. Dissolution Behavior in the Paddy Environment, 3.2. In the late rice season, plant available–silicon concentration in soil of the Si4 and Si5 treatments was 35.5% and 41.5% higher than in the control treatment, respectively. Silicon is taken up by roots in the form of silicic acid (H4SiO4), and mainly distributed in rice straw (leaf + stem) [2]. With the rapid industrialization and economic development in the recent decades, soil heavy metal pollution has been becoming a serious environmental problem in China [11, 12]. A one-way ANOVA was used for statistical analysis and L.S.D. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. However, it is strange to note that plant available–silicon concentration in soil of the Si5 treatment in the late rice season remained unchanged as compared with the same treatment in the early rice season (Fig 2). In addition steel slag has been recognized as a cost-effective amendment for in situ stabilization of heavy metals in soils [25, 26]. test was adopted to detect the significant difference (P<0.05) between the means of different treatments in the same rice season. Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. Steel slag is the main waste product in the steelmaking process. Soil Science and Plant Nutrition: Vol. Use of steel slag as a potential nutrient in fertilizer, industry analyst believe, will greatly cut down India’s dependency on fertilizer imports. There are two types of iron and steel slag, blast furnace slag consisting mainly of lime and silica and steel- making slag containing large proportions of iron oxide and other metallic compounds. Basic slag It is a by-product from the steel industry. Summary of harvest results in 2012 and 2013. NPK LTD, suppliers of steelworks slag (Ag Slag) from the Port Talbot South Wales steel works were responsible for reviving the production of agricultural slag from this site around 25 years ago after a break of many years. No, Is the Subject Area "Soil pH" applicable to this article? Blast furnace slag is made during the melting and reduction of iron ore in a blast furnace. Silicon application significantly decreased Cd concentration in the xylem sap and Si-mediated detoxification of Cd in maize plants [46]. The residual effect of the fertilizer was kept observed in 2013, although the additional fertilizer was not applied. Silicate lime fertilisers (blast furnace lime and converter lime) are approved fertilizers in Germany since more than 60 and 30 years, respectively. No, Is the Subject Area "Heavy metals" applicable to this article? broad scope, and wide readership – a perfect fit for your research every time. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO2 per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. Working topics. The paddy fields were divided into nine plots (20 m × 12 m in width); 200 g/m2 and 400 g/m2 of fertilizer made of slag were applied to a part of the rice field in 2012, and then the rice cultivation experiment was conducted. Basic slag was thought by many to be the best grassland fertiliser ever. No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, https://doi.org/10.1371/journal.pone.0168163, http://data.stats.gov.cn/workspace/index?m=hgnd, http://www.worldsteel.org/media-centre/press-releases/2012/12-2012-crude-steel. 6) In Japan, steelmaking slag has been registered as a fertilizer, but less than 1% of the slag generated from the steelmaking shops has been used as a fertilizer or material for soil remediation. From the results above, it is confirmed that the general trend of pore water and soil in the actual paddy can be simulated by the column test, except for the change in Si content with time in pore water. The range of Ca content was also close to that observed with column test, shown in Fig. So, application of steel slag can provide with silicon nutrition and is beneficial for sustainability of rice production. (2) The pH values increased over time until they reached a constant near 30 days; they also rose consistently throughout the experiment by the application of fertilizer made of slag. https://doi.org/10.1371/journal.pone.0168163.g006. The maximum application rate of Mo slag to soil in present study is 10.0% (w/w). J. Ma and E. Takahashi E: Soil, Fertilizer, and Plant Silicon Research in Japan, Elsevier, Amsterdam, (2002), 107. After the vessel had been cooled, the solution was filtered and diluted to 25 mL with 0.5 M HCl. https://doi.org/10.1371/journal.pone.0168163.s001, https://doi.org/10.1371/journal.pone.0168163.s002, https://doi.org/10.1371/journal.pone.0168163.s003, https://doi.org/10.1371/journal.pone.0168163.s004. Kim,  S.  Ueda and  S.  Kitamura: https://doi.org/10.2355/isijinternational.ISIJINT-2015-640, http://www.maff.go.jp/j/press/nousin/sekkei/110624.html. Yes Examples of traditional applications of ferrous slag are the use as aggregates and cement component in the building sector or as fertilizer. Previous researches demonstrated that silicon per se decreased Cd uptake and transport into shoots and rice grain by co-deposition of metals with silicates in the root cell walls [55, 56]. PLOS ONE promises fair, rigorous peer review, lignite sludge pond sludgeSucrose slagstarch pulp Bentonite clay Diatomite c materials mix with mineral materials Organic Ball Pellets Fertilizer Production Line Organic fertilizer production line is a complete set of equipment from raw materials collection to the organic fertilizer granules packing Two factors could account for this phenomenon. In the early rice season, dry weight of straw of Si4 and Si5 treatments were 9.52% and 11.9% higher than that of CK treatment, respectively; grain yield of Si4 and Si5 treatments were 11.9% and 13.9% higher than that of CK treatment, respectively. However, this fact sheet will mainly focus on solid co-products. In the same treatment with slag, lower Cd concentrations were observed in the late rice than in the early rice. These are competitive raw materials for industrial mineral industry. Change in the Ca content of pore water in paddy field in 2012 and 2013. pan for its total amount of crude steel production, which is over 100 million tons. https://doi.org/10.1371/journal.pone.0168163.g004. Na content in the stems and leaves of the paddy harvested from each group of plots in 2012 and 2013. https://doi.org/10.1371/journal.pone.0168163.g001. Soil … The Na contents of soil solution in the plot where the fertilizer was applied were relatively high, and this trend was also observed in the column test, as shown in Fig. Table 1. The late rice transplanted rice seedlings at 18 July, and harvest at 20 December. In the late rice season, application of slag at a rate above higher or equal to 1 200 mg plant-available SiO2 per kg soil significantly increased dry weight of straw compared with CK treatment, and equal to 1 600 mg plant-available SiO2 per kg soil significantly increased grain yield, with 14.3% and 16.7% higher in the Si4 and Si5 treatments respectively. https://doi.org/10.1371/journal.pone.0168163.s007, This work was jointly supported by The National Natural Science Foundation of China entitled “Immobilization of heavy metals in a contaminated paddy soil using nano-slag-based silicon fertilizer and ecological assessment” (Approved No. Lead was mainly distributed in the Fe/Mn oxide fraction (F2, 50%) and residual fraction (F4, 40%). A silicon–potash fertilizer prepared from magnesium slag and how it can improve soil fertility and agronomic performance. Most environmental standards for soils contaminated with heavy metals are based on their total concentrations. 9 (2018) 4/14 3 Fertilizer Components of DM Calcium Silicate One type of slag fertilizer for growing paddy rice is slag siliceous fertilizer (registration name: Calcium Silicate) made from iron and steel slag. (2019). '•The slag from the Thomas-Gilchrist process for making steel has long been supposed to have valuable properties as a manure. In the Bessemer converter, there is a lining of lime which, in the process of manufacturing the steel, takes up a large percentage of phosphorus, in the form of phosphoric acid. How to Garden With Basic Slag. In the early rice season, plant available–silicon concentration in soil of the Si5 treatment was significantly higher than in the other treatments, and 59% higher than in the control treatment. It is found to occur mostly as calcium phosphate (Tricalcium phosphate). 51509249), The 12 th Five-year Key Programs entitled “Techniques for Agricultural Use of Steel and Iron Slag: Research and Demonstration”, China (2013BAB03B02). Fertilizers made of blast furnace slag or steelmaking slag are categorized in slag silicate fertilizer, byproduced lime fertilizer, slag phosphate fertilizer or iron matter of spe-cial fertilizer. Yes In 2013, the rice cultivation experiment was conducted again without the application of fertilizer made of steelmaking slag. The storage of steel slag not only occupies a large amount of cultivated land, pollutes the environment, but also recovers 7%-15% of steel in steel slag.Steel slag can be used as smelting solvent, cement raw material, building aggregate, foundation backfill, railway ballast and road paving, brick and other building materials, steel slag fertilizer and soil improver. By the application of fertilizer made of slag, Ca content recovered to the same level as OS. 274-280. 3, pp. In the present study, disease incidence and severity (e.g., blast, sheath blight and leaf spot etc.) In this case, the effect of the application of fertilizer made of slag was not clear. Portions of the soil samples were air-dried for analysis of basic chemical parameters, and the remaining samples were freeze-dried for analysis of heavy metal fractions. In the present study, a pot experiments were carried out (1) to assess the effect of application rates of steel slag on improving soil acidity and silicon-availability (2) to demonstrate the effects of steel slags on the immobilization of heavy metals in contaminated soil, (3) to test the impacts of slag application on rice productivity and metals accumulation. Thomas and Gilchrist method The authors gratefully acknowledge the financial support provided by ISIJ innovative program for advanced technology, Iron & Steel Institute of Japan (ISIJ). About Us. In the past steelmaking processes were exclusively designed for the production of specific quality of iron and steel. Effect of steel slag fertilizer application on total Cd concentration in soil. Though India’s fertilizer production has improved in recent times, it still depends on imports to bridge the demand-supply gap. The soil used was sampled from Qiyang, Hunan province of South China, (no specific permissions were required for soil sampling in this location and the field in this study did not involve endangered or protected species). C. Effect of steel slag fertilizer application on relative content of Pb in each fraction of soil in early rice. Lead was found to be mainly distributed in the F2 (50%) and F4 (40%) fractions. The Cd concentration of early rice grain in the Si5 treatment and that of late rice grain in the Si4 and Si5 treatments were all below the maximum allowable limit level (0.2 mg kg-1) (GB 2762–2005). D. Effect of steel slag fertilizer application on relative content of Pb in each fraction of soil in late rice, https://doi.org/10.1371/journal.pone.0168163.s006. Is the Subject Area "Rice" applicable to this article? A representative sample of up to 0.5 g was digested in 9 mL of concentrated nitric acid (HNO3) and 3 mL of concentrated hydrofluoric acid for 15 minutes in a suitable laboratory microwave system. Table 2. Agricultural Fertilizer Production Steel slag could also be used as a raw material for soil improvement and fertilizer production. For more information about PLOS Subject Areas, click Si deficiency in paddy soil has been recognized as a limiting factor for rice production [2, 8]. Production of slag silicate fertilizer in Japan peaked at 1,400,000 t per year in 1968 (Kato 2002) and decreased Correspondence: K. ITO, Advanced Technology Research Laboratories, Nippon Steel & Sumitomo Metal Corporation, 20-1 Shintomi, Futtsu, Chiba 2938511, Japan. M.  Numata,  N.  Maruoka,  S-j. Second, the large surface area and porosity of steel slag helped to immobilize Cd through adsorption [50, 51]. Thus, steel slags can be considered as a sustainable alternative to agricultural practice. Data are means of three replicates. Therefore, it is necessary to find an economical method for remediation of heavy metals contaminated paddy soil. These pots were incubated for 30 days after addition of slags and watered daily with distilled water to maintain 2–3 cm submergence throughout the experimental period. Kim and  S.  Kitamura: H.  Shinozaki: Enchiridion of Fertilizer, 6th ed., Rural Culture Association Japan, Tokyo, (2008). Two days later, uniform seedlings with three leaves fully expanded were transplanted at two seedlings per pot. In this experiment, total concentration of Cd and Pb in soil was not significantly affected by application of steel slag (Fig 5A and 5B). POSCO has contributed to increase farm income by continuously supplying slag to fertilizer companies since 1974, the year after the Pohang Works began operation. In China, the first steel slag fertilizer program invested by Taiyuan Iron and Steel Group and Harsco Corporation of the USA started building in 2011 . Application of steel slag to crop land is an attractive disposal with high economic and environmental benefit. Process gases, for example, from the coke oven, BF or BOF are also important co-products. With 80% of the paddy fields in China being located in the subtropics, it is necessary to demonstrate the effects of steel slag application on rice yield and heavy metal immobilization in the subtropical Chinese paddy fields. The results are summarized below. Funding: The National Natural Science Foundation of China entitled “Immobilization of heavy metals in a contaminated paddy soil using nano-slag-based silicon fertilizer and ecological assessment” (Approved No. A. R.  Yeo,  S. A. In tropical and subtropical areas, plant-available Si is low in these highly-weathered soil owing to heavy desilication-aluminization [7]. Table 3 show the BCR concentrations of heavy metals in steel slag. Affiliation Application of steel slag decreased the percentage of F1 and increased the percentage of F3, whereas there was little change in F2 or F4 fractions (Fig 6C and 6D). PLoS ONE 11(12): Five Si treatments with three replicates each were designed. Rice (Oryza sativa L. cv. ( Montalvo et al., 2018 ). Except for the Si5 treatment, plant available–silicon concentration in soil of the same treatment was slightly higher in the late rice season than in the early rice season. No, Is the Subject Area "Metallic lead" applicable to this article? Steel slag used in this experiment was extremely alkaline with its pH value approaching 12. Fertilizer. Application of steel salg also increased rice grain yield and Si concentration in rice straws. Effect of steel slag fertilizer application on plant available-silicon concentration in soil. In addition to these three components, steelmaking slag also contains components such as FeO, MnO, and P2O5, and is used for a broad range of agricultural purposes, including dry field farming and pastures in addition to rice cultivation. This decrease, however, could not be only attributed to the pH-rise-caused immobilization of Cd in soil. The fertilizer contains 25-30% of soluble silicic acid that boosts photosynthesis in rice plants; and 40-48% of alkalinity which improves soil quality. During the rotation of the mill, under the centrifugal force and dropping speed of grinding medium (steel ball), the steel slag is impacted and ground, and by repeating above actions, the steel slag … Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. The dry weight of these tissues was recorded after being oven-dried at 75°C till a constant weight. Fertilizers made of steelmaking slag are important inexpensive materials for recovering degraded paddy fields. Slag ― a mixture of silica and calcium, magnesium and iron oxides ― can be used as a fertilizer that can assist in fortifying disease resistance in rice because of its mineral components. The concentration of Cd and Pb was determined with ICP-MS, while that of Hg and As was measured with atomic fluorescence spectrophotometer (AFS-2202). Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. Data Availability: All relevant data are within the paper and its Supporting Information files. Competing interests: The authors have declared that no competing interests exist. Copyright: © 2016 Ning et al. The feasibility of steel slag used as an iron fertilizer was studied in a pot experiment with corn. Keywords: slag, environment, iron, steel, recycling, blast furnace, steelmaking, ladle metallurgy, slag splashing, construction. Significant amount of H+ and Al3+, which is over 100 million tons examples of traditional applications of slag... The range of Si content of pore water in 2012 dumped ; nowadays they are marketable. At an ever increasing rate by its mid-late maturity 6, but the change in the treatment! Soil used had a strong buffering capacity at this pH value range ( near neutral ) and )... Yield of brown rice yields increased by approximately 7–9 % in 2012 the... Dissolution behaviors of nutrient elements from fertilizer made of steelmaking slag for fertilizer 18... 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