Open Access is an initiative that aims to make scientific research freely available to all. To date our community has made over 100 million downloads. It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. How? By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers.
We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too.
To purchase hard copies of this book, please contact the representative in India:
CBS Publishers & Distributors Pvt. Ltd.
www.cbspd.com
|
customercare@cbspd.com
Linz-Donawitz (LD) slag, a by-product of steel manufacturing process, is rich in iron oxide, calcium oxide, silica, various macro, and micronutrients as well as varying degrees of heavy metals residues. The steel slag, thus, presents an opportunity for their utilization in agriculture beyond the conventional routes of consumption in cement, transport, construction industries. In this chapter, we explore a sustainable waste management technology for utilizing LD slag in the development of sulfur enriched nutrient supplement “Dhurvi Gold (DG)” and determine its effect on physico-chemical characteristics of the soil and its impact in the growth, quality, and economic yield on selected crops under natural field conditions. Heavy metal accumulation among the plant parts following the supplementation with DG was also studied. The results indicate the farming and economic benefits of utilizing DG in agriculture, which thus, presents itself as an opportunity both for the steel industry and the agriculture sector desirable for the development of a sustainable strategy for management of steel (LD)-slag. However, it is important to determine the long-term effects of the steel slag-based fertilizers on physico-chemical and biological characteristics of soil including accumulation of heavy metals in soil-plant continuum, if any.
Division of Environment Science, ICAR-Indian Agricultural Research Institute, New Delhi, India
Shrenivas Ashrit
Tata Steel Limited, Jamshedpur, Jharkhand, India
Manoj Shrivastava
Division of Environment Science, ICAR-Indian Agricultural Research Institute, New Delhi, India
Kalidindi Usha
Division of Environment Science, ICAR-Indian Agricultural Research Institute, New Delhi, India
Pratik Swarup Dash
Tata Steel Limited, Jamshedpur, Jharkhand, India
Prem Ganesh
Tata Steel Limited, Jamshedpur, Jharkhand, India
Subrat Kumar Baral
Tata Steel Limited, Jamshedpur, Jharkhand, India
*Address all correspondence to: bhupindersinghiari@yahoo.com
1. Introduction
India is the second-largest producer of steel after China, and it is likely to continue its global dominance in steel production in years to come. However, the strides being made, the steel industry needs to be based on green processes in terms of carbon emissions and waste management. Huge quantities of steel slag get generated during the production of steel from the iron ore, the major raw material, which is processed via the BF/BOF or LD routes [1, 2, 3]. It is estimated that the steel industry produces about 125 kg of steel slag per ton of steel produced during the Linz-Donawitz (LD) process [4]. While the BF-slag is utilized in cement production, management of the LD slag is a concern, several possible routes are being explored for sustainable management of LD slag [5].
The LD steel slag is rich in calcium-bearing silicates and free lime along with metallic iron. A typical chemical composition of the reject portion can be represented as 47–52% CaO, 2–13% free lime, 12–19% Fe, 1.5–2% P, 1.5–2% Al2O3, and 11–18% SiO2. This slag is processed in a waste recycling plant (WRP) so as to separate the magnetic iron portion and the non-magnetic portion by water quenching and solidification and by using a series of magnetic separators. This is followed by crushing the slag to −300, −80, and − 6 mm size fractions and subjecting it to roll magnetic separators so as to recover the metallic iron. At this point, iron is in the form of FeO and Fe2O3 as metallic iron is recovered in WRP [6, 7, 8].
The LD slag is used as an aggregate in the construction of roads [9, 10, 11]. Other applications include the use of LD slag as a starting material for production of cement clinker and as a fertilizer in the agricultural sector [12, 13]. Significant positive effect of steel slag-based silicate fertilizer application on shoot silica content and growth of paddy on acidic soil has been reported [14]. In line with the enormous stockpile of LD slag being generated by the steel industries, other applications need to be identified, which can be helpful in the synthesis of value-added products of industrial importance [15]. Use of LD slag either in un-amended form as a soil conditioner or in an amended or modified form as a soil fertilizer could open up new avenues and opportunities for both the steel and the agriculture sector with positive environmental significance [16]. The following sections provide details of the development of a LD slag-based sulfur-enriched multi-nutrient fertilizer and soil conditioner and an evaluation of its effect on agricultural soils and selected crop productivity and its potential enrichment of the soils with undesirable heavy metal accumulation along the soil-plant continuum.
2.1 Production of LD slag-based synthetic gypsum “Dhurvi Gold”
Dhurvi Gold (calcium sulphate) was produced from −60 mesh size LD slag fines obtained from Tata Steel Limited, Jamshedpur, India. The production of synthetic gypsum using LD slag was carried out by acid digestion of LD fines with concentrated sulfuric acid followed by pyrolysis steps at temperatures ranging between 105 and 900°C [17]. The digestion process helps in leaching of all major impurities and other minor elements present into the solution and precipitation of calcium as calcium sulphate [18] while also precipitating the silica. The slurry so formed was neutralized to pH 7.0 using 20% lime solution and filtered through Whatman no. 41 membranes. The solid residue so collected on filter paper, “the Dhurvi Gold,” was washed with double-distilled water and allowed to dry at temperature below 60°C for 24 h. A general scheme of DG production is given in Figure 1. Further, the nutrient content of DG was determined using ICP-OES following standard procedure [19].
Figure 1.
Flow chart of lab-scale production of Dhurvi Gold [17].
The LD slag-based nutrient fertilizer, DG, described in this study, was characterized by ICP and various other characterization techniques [20] such as X-ray diffraction (XRD), thermogravimetric analyzer, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS).
2.2 Crop response to DG application at the farm level
Field treatments were identified and undertaken to evaluate the effect of DG on crop growth, yield, and nutritional quality and on soil attributes across two separate experiments, wherein experiment 1 studied the contribution of varying doses of DG as the source of mineral nutrients to plant and soil health under full and half the dose of the recommended fertilizer (NPK), while the second experiment involved assessment of crop response to LD slag (LDS) and the effect of nutrient-solubilizing bacteria and fungi (PSB and PSF, respectively) and NPK availability (recommended dose of fertilizer (RDF) and half of the RDF on the vegetative and reproductive crop yield.
Treatment details under Experiment-I are as follows: T1: 100% NPK (Recommended dose of the crop); T2: 50% NPK + 5 t/ha FYM; T3: T1 + 30 kg/ha sulfur as DG; T4: T1 + 45 kg/ha sulfur as DG; T5: T1+ 60 kg/ha sulfur as DG; T6: T2 + 30 kg/ha sulfur as DG; T7: T2 + 45 kg/ha sulfur as DG; and T8: T2 + 60 kg/ha sulfur as DG. Meanwhile, the treatments under Experiment-II conducted with LD-slag (LDS) were: T1: RDF; T2: 50% of T1 + 5 t/ha FYM; T3: T1 + 0.5 t/ha LDS; T4: T2 + 0.5 t/ha LDS; T5: 0.5 t/ha LDS; T6: 0.5 t/ha LDS + PSF; T7: 0.5 t/ha LDS + PSB; and T8 = 0.5 t/ha LDS + PSF + PSB. All experiments were performed with a minimum of three replicates following the randomized block design (RBD). Crop response to both DG and LD slag was determined in brinjal (Solanum melongena L) cv Pusa hybrid-6 and okra (Abelmoschus esculentus) cv DOV 92. Observations in respect of plant biomass, macronutrients (P, K, S and Ca), micronutrients (Fe, Zn, Cu and Mn), heavy metals (Cd, Pb, Cr), beneficial nutrient: Na, and economic yield were recorded.
Experiments involved studies on crops’ growth and yield response of Dhurvi Gold and LD slag with recommended (RDF), reduced NPK (50% RDF) nutrition, and biological amendments as stated in earlier sections in both experimental vegetable crops. A control treatment without application of any fertilizer and DG was also maintained.
3.1 Production and characterization of LD slag-based synthetic gypsum “Dhurvi Gold”
Dhurvi Gold produced from LD fines not only was comparable to gypsum but also may replace natural gypsum in terms of varied applications including its use in the cement industry [21] and as a starting material for production of different preformed building elements and plaster products in the medical field. Gypsum is also used as a soil conditioner on alkaline soils [22]. We believe that the LD slag-based Dhurvi Gold, a synthetic gypsum, can replace natural gypsum in the cement industry [23], thus helping us conserve the resource of natural gypsum. Also, Dhurvi Gold produced from the industrial waste can supplement gypsum requirement for various chemical industries. Researchers at the Chemical Laboratory, Tata Steel Limited, thus, developed Dhurvi Gold, which is yellow in color owing to the presence of iron. Use of LD slag as liming agent on acid soils has also been reported [24].
The synthesis of DG helped to achieve a major objective in environmental sustainability of steel production by presenting a route for the synthesis of a value-added product (synthetic gypsum) from LD slag, which is an industrial waste product of the steel industry [17, 25]. This is an important development and a step forward for generating wealth from waste. The composition of DG, a source of sulfur and other macro- and micronutrients, is given in Table 1. The DG has a major amount of sulfur, which is about 14–16%. For experimental purposes and for assessing the crop response to application of DG, all calculations were done taking the S content of DG as 16%.
Parameters
Specifications (Min)
Typical Range, %
Ca
=
23.0%+
23 - 28
Major
S
=
14.0%+
14 - 20
SiO2
=
3.00%+
3 - 7
Additional nutrients
Fe
=
2.00%+
2 - 7
MgO
=
0.5 - 1.00%+
0.5 – 2.0
P2O5
=
0.50 – 0.90+
0.50 – 1.5
MnO
=
0.10%+
Max 0,15
PH
=
7.5 – 8.0 (Very good for application to all soils)
Table 1.
Nutritional characteristics of LD slag-based synthetic gypsum, Dhurvi Gold [26].
3.2 Effect of Dhurvi Gold on brinjal (Solanum melongena)
A distinct positive effect of DG on shoot mass of brinjal (Solanum melongena) plants was observed at all levels of applications (30, 45, 60 kg S/ha) under both 100% & 50% NPK when compared with respective NPK and zero fertilizer controls. Positive effect of DG on shoot mass was higher under 100% NPK than 50% NPK treatments. Fruit yield per plant was also improved under the DG application; however, the most significant increase was observed at 30 kg S/ha dose under both 100 and 50% NPK treatments. Increase in fruit yield per plant observed with DG was improved when compared with respective NPK controls. A similar positive effect of DG on individual fruit mass was observed under 30 and 45 Kg S/ha DG doses with both 100 and 50% NPK treatments (T1 and T2). The increase in individual fruit mass at 60 kg S/ha treatment was not significant when compared with respective NPK control (Figure 2).
Figure 2.
Effect of Dhurvi Gold on shoot mass and fruit yield attributes in brinjal (Solanum melongena) at harvest.
Change in essential and beneficial mineral element content and those for the toxic heavy metals as affected under an interactive influence of NPK and DG application were measured. K concentration of the shoot in general was 2–3 folds lower than that of fruit across all treatments. A significant increase in fruit K was, however, noticed with increasing concentration of 30–60 kg S/ha under 100% NPK treatment when compared with the respective control. On the other hand, an insignificant change in shoot and fruit Ca was observed under individual interactive treatment of NPK and DG, except that at the highest dose of DG application (60 kg S/ha), a higher increase in shoot and fruit Ca was evidenced under both T1 and T2 (100 and 50%) NPK when compared with respective treatment controls (Figure 3).
Figure 3.
Effect of Dhurvi Gold on potassium and calcium of shoot and fruit in brinjal (Solanum melongena) at harvest.
A DG dose-dependent increase in shoot phosphorous (P) was observed under both 100 and 50% NPK treatments up to 45 kg S/ha level, beyond which a decline was observed. A similar significant increase in fruit P was observed at all DG treatments under both 100 and 50% NPK levels, when compared with respective treatment controls. More or less a similar P concentration was observed in the shoot and fruit of brinjal (Solanum melongena) across the treatments. A significant increase in shoot and fruit S content was observed under the variable NPK treatments with different doses of DG (30. 45, 60 kg S/ha) when compared with respective fertilizer and absolute controls. The response in shoot S was, however, more marked under the 100% NPK than the 50% NPK treatment. Fruit S, on the other hand, showed more or less a similar incremental response under both 100 and 50% NPK complementations (Figure 4).
Figure 4.
Effect of Dhurvi Gold on phosphorus and sulfur content of shoot and fruit in brinjal (Solanum melongena) at harvest.
A higher shoot iron (Fe) content was observed under the increasing DG dose, more so with 100% NPK when compared with their respective fertilizer and absolute controls. In general, no significant increase in the fruit Fe was observed under 100% NPK with DG treatment. However, the increase in fruit Fe was significant under 50% NPK at (30 and 45 kg S/ha) DG application when compared with respective controls (Figure 5). A positive effect of steel slag application as an alternate to iron fertilizer was observed in corn in terms of plant growth and soil micronutrients [13].
Figure 5.
Effect of Dhurvi Gold on iron and manganese content of shoot and fruit in brinjal (Solanum melongena) at harvest.
It was also observed that the shoot manganese (Mn) concentration was higher than the fruit Mn levels across experimental treatments. A significant increase was observed at 60 kg S/ha DG under both 100 and 50% NPK treatments when compared with other DG doses and respective fertilizer and absolute controls. No significant change in Mn level was, however, observed under the DG application treatment irrespective of NPK and DG doses except under T7 (i.e. 45Kg S/ha DG + 50% NPK), which showed a higher increase in fruit Mn when compared to other experimental treatments and controls (Figure 5). A significant increase in the shoot zinc (Zn) irrespective of DG level was observed under 100% NPK supplementation when compared with its respective control; however, under 50% NPK treatment, no significant effect of DG on shoot Zn was observed, which was similar to the pattern of variation observed for concentration of Fe and Mn. In the fruit, Zn concentration also did not vary with DG application except under T7 compared to other experimental treatments and controls (Figure 6).
Figure 6.
Effect of Dhurvi Gold on zinc and magnesium content of shoot and fruit in brinjal (Solanum melongena) at harvest.
An incremental increase in shoot and fruit magnesium (Mg) was observed under both 100 and 50% NPK supplementation treatments when compared with the irrespective fertilizer and absolute controls. Shoot Mg level was in general higher than the fruit Mg concentration, and the shoot-to-fruit translocation of Mg was observed to be higher under 50% NPK than 100% NPK treatment (Figure 6).
Certain heavy metals are unwanted inputs that may cause phytotoxicity effect; thus, it is important to understand the levels of these metals in soil and plants. Chromium (Cr) is an element of concern in respect of utilization of steel slag [27] in agriculture. In the present experiment, the concentrations of Cr alongside cadmium (Cd) and lead (Pb) both in shoot and in fruit under different experimental treatments were below the detection limit showing that application of the fertilizer did not pose phytotoxicity that could affect human/animal health issues in respect of use of DG application in farms.
3.3 Effect of LD slag on brinjal (Solanum melongena)
Effect of LD slag on growth and nutritional characteristics of brinjal (Solanum melongena) crop when supplemented with 100 and 50% NPK and with different microbiological interventions such as phosphate solubilizing bacteria (PSB), phosphate solubilizing fungi (PSF), and their combination was studied, and results are presented in the following section. Plant shoot mass, in general, declined with LD slag application without any NPK supplement when compared even with the absolute control. The microbiological amendment with both PSB, PSF, and their combination caused significant increase in shoot mass when compared with all other experimental treatments; a similar significant inhibition and increase in fruit yield were observed under LD alone and microbiological intervention, respectively. A look into the individual fruit mass shows that LD slag application reduced the fruit not much more than the fruit mass. Here again, the biological amendment improved the mass accumulation in fruits (Figure 7).
Figure 7.
Effect of LD slag on shoot mass and fruit yield attributes in brinjal (Solanum melongena) at harvest.
A comparison of potassium (K) concentration between shoot and fruit of LD slag-treated brinjal (Solanum melongena) plants showed a much higher level of K in the fruit than the shoot. Shoot K level did not change over control under different LD slag treatments with biological amendment. However, the fruit K level was improved with biological intervention given alongside LD slag when compared with LD slag alone or fertilizer and/or absolute controls. The LD-slag-alone treatment showed significant increase in fruit K when compared with all other experimental treatments (Figure 8). Since DG and LD slag are also a major source of Ca (Table 1), the effect of different experimental treatments on plant tissue Ca was determined and discussed. Shoot Ca concentration was higher under LD slag application; max Ca level was observed under T3 treatment that is 100% NPK and slag, while a reduced NPK supplementation alongside slag treatment inhibited the uptake and accumulation of Ca in the shoot. PSB alone and PSB in combination with PSF and alongside LD slag improved the shoot Ca level at par with the T3 treatment. Ca concentration in fruit was in general almost 3–4 times lower than that of shoot and increased with D slag application either with 100 or with 50% NPK supplementations when compared with respective controls. Max fruit Ca was observed under LD slag alone treatment (T5). Biological interventions also improved the fruit Ca level over different experimental controls; however, the effect was significant under LD slag + PSB treatment (T7) (Figure 8).
Figure 8.
Effect of LD slag on potassium and calcium content of shoot and fruit in brinjal (Solanum melongena) at harvest.
A significant increase in shoot P was observed with the use of phosphate-solubilizing bacteria and fungi or their combination; when applied alongside the LD slag to brinjal (Solanum melongena) plants, it caused a significant increase in the tissue P accumulation when compared with NPK fertilizer and absolute controls. The least tissue concentration of P was recorded for the LD-slag-alone treatment, while maximum increment in tissue P was evident under the combined intervention of PSB and PSF (Figure 9). Application of LD slag with variable NPK levels and biological amendment did not alter the fruit and shoot S content over the fertilizer and absolute controls. Application of LD slag alone (T5) did not inhibit the S uptake (Figure 10).
Figure 9.
Effect of LD slag on zinc and magnesium content of shoot and fruit in brinjal (Solanum melongena) at harvest.
Figure 10.
Effect of LD slag on phosphorus and sulfur content of shoot and fruit in brinjal (Solanum melongena) at harvest.
LD slag application with NPK supplementation in general did not improve the shoot Fe content when compared with respective fertilizer treatment and controls. A significant decline in shoot Fe accumulation was evident under the LD-slag-alone treatment (T5). Biological intervention seems to facilitate the availability, uptake, and accumulation of Fe from LD slag in the shoot. However, the Fe content in the fruit was unaffected by fertilizer (Figure 11). Variation in shoot and fruit Mn as affected by LD slag in conjunction with fertilizer and biological amendment is presented in Figure 12. Application of LD slag either with NPK amendment or with biological intervention did not alter the shoot Mn level when compared to the slag-alone treatment; however, an increase in shoot Mn was observed when LD slag was applied alongside 50% NPK (T4) in comparison with the (T2) control. No significant variation in fruit Mn concentration was, however, observed either with or without the fertilizer and biological amendment (Figure 11).
Figure 11.
Effect of LD slag on iron and manganese content of shoot and fruit in brinjal (Solanum melongena) at harvest.
Figure 12.
Effect of Dhurvi Gold (DG) on plant growth and fruit yield of okra (Abelmoschus esculentus) at harvest.
The significant positive effect of LD slag on shoot Zn when applied alongside 100 or 50% NPK or as biological amendment was recorded in comparison with the respective control treatments. PSB rather than PSF, when supplemented along with LD slag, improved shoot Zn concentration. An insignificant variation in fruit Zn level was observed under the various fertilizer and biological amendments of LD slag in brinjal (Solanum melongena) plants (Figure 13). Application of LD slag alongside NPK or biological amendment improved the shoot Mg concentration when compared with the respective fertilizer and absolute control treatments. The LD-slag-alone treatment reduced the uptake of Mg by brinjal (Solanum melongena) shoot; none of the experimental treatments/amendments caused significant intertreatment variation in the fruit Mg concentration either with or without the presence of LD slag (Figure 9).
Figure 13.
Effect of Dhurvi Gold (DG) on potassium and calcium content of shoot and fruit of okra at harvest.
Even with the LD slag application, we did not observe any built up of heavy metals in the shoot and fruit of brinjal (Solanum melongena), all of which were in the undetectable range and may be attributed to the dilution or varietal affect.
3.4 Effect of DG on okra (Abelmoschus esculentus)
Effect of DG with 100% and 50% RDF (NPK) application on plant growth and development, economic production, and accumulation of essential macro- and micronutrients, beneficial elements, and heavy metals, Pb, Cd and Cr, was studied in the shoot and fruits of okra (Abelmoschus esculentus). Results are surmised as follows: DG application at all doses under 100% NPK yielded a better shoot growth over the respective fertilizer control (T1). Same was also true for the other fertilizer application treatment, that is, 50% NPK, which although showed an increase in shoot mass with DG when compared to the fertilizer-alone-control treatment (T2), the plant response under T1 was higher than T2 treatments both alone and in combination of DG. A similar increase in fruit yield per plant and single fruit mass was evident under RDF treatment when supplemented with different amounts of DG. The response of DG under 50% RDF treatment was not significant (Figure 12).
DG application improved the shoot K level when supplemented with the recommended dose of NPK fertilizer; however, under 50% RDF condition, an insignificant effect of DG supplementation on K concentration of the shoot was observed when compared with their respective fertilizer controls (T1 and T2). Similarly, an increase in fruit K was evident with DG under 100% RDF at 30 and 45 kg dose (T3 and T4) and at 30 kg DG dose (T6) with 50% RDF (Figure 14). Further, an increase in calcium content of shoot was observed at all doses of DG both at RDF and at 50% RDF. However, the increase in calcium content across DG treatments was higher at RDF than at 50% RDF treatment over absolute and respective NPK controls. A similar pattern of variation between the NPK treatments under variable DG doses was also evident for the fruit calcium content. T3 and T4 treatments showed maximum fruit calcium content (Figure 13).
Figure 14.
Effect of Dhurvi Gold (DG) on iron and manganese content of shoot and fruit of okra (Abelmoschus esculentus) at harvest.
Okra (Abelmoschus esculentus) with DG shoot phosphorus (P) content in general increased with increasing level of DG application; however, the P content with DG was more significant at 50% RDF when compared with its respective control (T2) in comparison with the observed increase with DG under RDF viz-a-viz its control treatment (T1). Increase in fruit P content was observed with DG irrespective of the dose and the NPK availability application to the soil. Different DG treatments, however, did not vary in terms of their fruit P content with an exception of (T8), which showed marginal decline when compared with T6, T7, and its control (T2). A significant increase in shoot S and the fruit S content was observed under the DG application irrespective of the DG dose and the NPK availability in the soil (T3-T8) when compared with the experimental control (T1 and T2). It so appears that the S application in okra (Abelmoschus esculentus) benefits the crop in improving its shoot and fruit S content (Figure 15).
Figure 15.
Effect of Dhurvi Gold (DG) on phosphorus and sulfur content of shoot and fruit of okra at harvest.
A look into the micronutrient content of okra (Abelmoschus esculentus) as affected by the application of DG and availability of NPK in the rhizosphere (Figure 14) shows a significant increase in shoot Fe content across DG application treatments (T3-T8), irrespective of NPK application treatments (RDF and 50% RDF) over their respective controls T1 and T2. A similar increase was also evident for the Fe content of the okra (Abelmoschus esculentus) fruit; however, the increase was dependent on DG application at RDF treatment. Fe content of the fruit was also higher with DG application at 50% RDF compared to its respective control (T2); however, the variation between treatments (T2-T6) was insignificant (Figure 14). Mn content of the shoot, on the other hand, increased at T3 but not at T4 and T5 when compared to its respective control T1; however, at 50% RDF (T2), the supplementation of DG irrespective of the dose caused a more significant but similar increase in shoot Mn between T6 and T8 over its respective control (T2). Fruit Mn content, on the other hand, showed either a marginal or an insignificant increase in different doses of DG application (T3-T8) over the respective NPK controls (T1-T2) with an exception of T4, which showed a significant higher fruit Mn content (Figure 14). Observed variations in shoot and fruit Zn and Mg content as effected by DG treatment are shown in Figure 16. Shoot Zn concentration with DG doses 30, 40, and 60 kg S/ ha with 100% RDF had a slight increase when compared with its respective control (T1 and T2), whereas the shoot Zn concentration increased in T4 as compared to the controls (T1 and T2). Mg content with DG application in shoot and fruit did not show any significant change (Figure 16).
Figure 16.
Effect of Dhurvi Gold (DG) on zinc and magnesium content of shoot and fruit of okra (Abelmoschus esculentus) at harvest.
Here again, undetectable levels of heavy metal accumulation of Cr, Pb, and Cd were observed in the shoot and fruits of okra (Abelmoschus esculentus) at harvest under DG, irrespective of its dose of application with full or 50% NPK treatment.
3.5 Effect of LD slag on okra (Abelmoschus esculentus)
Effect of LD slag on growth and yield attributes and accumulation of macro- and micronutrient and phytotoxic heavy metals of consequence (Pb, Cd and Cr) in the shoot and the fruit of okra (Abelmoschus esculentus) is presented in the subsequent sections.
Shoot mass was insignificantly affected by the application of LD slag except in case of T8 where the microbial interventions improved the vegetative growth of okra (Abelmoschus esculentus) (Figure 17). Fruit yield was also not affected by the application of LD slag alone but when complemented with microbial interventions (PSB and PSF), the fruit yield was improved over the T1, T2, and absolute controls. LD slag application alone without any biological amendment showed a reduced content of potassium in the shoot and the fruit when compared with all other experimental treatments (Figure 18). An increase in shoot and fruit K was observed at 100% NPK treatments either with or without LD slag. Biological amendment improved the shoot and fruit K level when compared with the LD-slag-alone treatment (T5). A significant increase in shoot and fruit Ca was evident with LD slag application whether given with 100% or 50% NPK or with different biological amendments (PSB or PSF or their combination).
Figure 17.
Effect of LD slag on shoot mass and fruit yield of okra (Abelmoschus esculentus) at harvest.
Figure 18.
Effect of LD slag on potassium and calcium content of shoot and fruit of okra (Abelmoschus esculentus) at harvest.
An increase in shoot and fruit P content was observed with PSB and PSF treatments or their combination, when co-applied with LD slag compared to the LD-slag-alone treatment (T5). A similar increase in fruit and shoot P was also evident under 100% or 50% NPK when compared to the absolute control (Figure 19). No significant variation in shoot and fruit S was observed across treatments of LD slag with 100/50% NPK or with the investigated biological amendments. A significant increase in shoot and fruit Fe content was observed with LD slag treatment when made alone (T5) or in complementation with 100% or 50% NPK (T3 to T4) or any of the biological amendments (T6 to T8) when compared to the respective NPK controls (T1 and T2) and absolute control. An increase in shoot Mn was observed with 100% NPK and reduced at 50% NPK level when supplied either with or without LD slag. The LD-slag-alone treatment showed Mn level similar to 100% NPK treatments, and an increase in Mn content was observed with the biological treatments with the PSB + PSF combination treatment (Figure 20). More or less a similar pattern of response in terms of shoot Mn accumulation was observed in the fruits. However, shoot-to-fruit translocation of Mn was somewhat restricted or inhibited under LD slag alone (T5) (Figure 20).
Figure 19.
Effect of LD slag on phosphorus and sulfur content of shoot and fruit of okra (Abelmoschus esculentus) at harvest.
Figure 20.
Effect of LD slag on iron and manganese content of shoot and fruit of okra (Abelmoschus esculentus) at harvest.
A significant increase in shoot zinc but a decline in fruit Zn was observed when LD slag was applied. The highest content of shoot Zn was observed when slag was applied along with NPK, both at 100% and at 50% RDF levels (Figure 21). Biological amendments (T6 to T8) in comparison to LD slag alone increased the shoot Zn but reduced its translocation and accumulation in the fruits when compared with the fertilizer and absolute controls. No significant change in shoot or fruit Mg was evident under different fertilizer or biological treatments with or without LD slag application (Figure 21). An increase in shoot and fruit Pb level was observed with co-slag application (Treatments T3 to T8) when made with fertilizer or biological amendments compared to treatment and absolute controls. Undetectable levels of Cd and Cr were observed in response to LD slag application in okra (Abelmoschus esculentus) (Figure 22).
Figure 21.
Effect of LD slag on zinc and magnesium content of shoot and fruit of okra (Abelmoschus esculentus) at harvest.
Figure 22.
Effect of LD slag on lead content of shoot and fruit of okra (Abelmoschus esculentus) at harvest (cadmium and chromium levels of shoot and fruit were below the detectable limit).
The above results on crop response to DG and LD slag across different crops indicate a genetic variation besides reasserting and underlining the observation that DG application is beneficial for improving the vegetative and the economic yield and their nutritional attributes. LD slag as such is not advocated for direct application; however, biological amendments can be useful in improving the advantages of the slag for plant growth and development. A positive effect of steel slag application on soil health, environmental stability and sustainability, and food security has also been suggested by Das et al. [28]. Das et al. [29] also showed a significant impact of steel slag amendment on soil biological activity and related enzymes. Further, an immobilization of heavy metal in presence of slag-based fertilizer has also been reported by Yang et al. [30]. In the present study, as such Pb but not Cd and Cr was detected in the shoot and the seed across the experimental crops. That too, the Pb content was lower and within the prescribed permissible limits of phytotoxicity. Further, this study also elucidated the effect of application of such waste to wealth-products on heavy metal accumulation and leaching, which were found to differ insignificantly between 0 and 15 and 15–30 cm soil depth.
In conclusion, the value-added transformed slag, Dhurvi Gold, developed and for which the crop response was determined in the present study, is likely to open up new vistas for sustainable utilization of steel slag, which at the moment is a major challenge for the steel industry. Development of slag-based products in Dhurvi Gold background will not only help in remediation of degraded soils but also boost the economy of both the steel and the agriculture sectors in the years to come. However, the emphasis as is always should be laid on conducting a detailed phytotoxicity and risk assessment, across short- and long-term application studies, before making any recommendation for its use under the farm condition. The study also shows that the technological advancement in terms of the development of slag-based novel/customized nutrient supplements and fertilizers is now not a dream but a reality, which will also open up other avenues for the steel-agro-allied industry.
We acknowledge the pioneering contribution of late Dr. Shrinivas Ashrit who dedicated his life to add value to the LD slag waste and to develop Dhurvi Gold. We hope to nurture his dream of ensuing success of Dhurvi Gold in agriculture as a mineral nutrient supplement and soil conditioner. We also acknowledge the funding support provided by Tata Steel Limited and the laboratory facilities and infrastructure support provided by ICAR-IARI.
1.Bell T. The Modern Steel Manufacturing Process. New York: Available from: https://www.thoughtco.com/steel-production-2340173 (As seen on 8.1.24)
2.Deo B, Boom R. Fundamentals of Steelmaking Metallurgy. New York: Prentice Hall International; 1993. ISBN 9780133453805. LCCN 92038513. OCLC 473115765
3.Turkdogan ET. Fundamentals of Steelmaking. London: Institute of Materials; 1996. ISBN 9781907625732. OCLC 701103539
4.Zhang L, Zhi J, Mei F, Zhu L, Jiang X, Shen J, et al. Basic oxygen furnace based steelmaking processes and cleanliness control at Baosteel. Ironmaking & Steelmaking. 2006;33(2):129-139. DOI: 10.1179/174328106X80127
5.Osman G, Karadag O, Oren OH, Bilir T. Steel slag and its applications in cement and concrete technology: A review. Construction and Building Materials. 2021;283:122783. ISSN 0950-0618. DOI: 10.1016/j.conbuildmat.2021.122783
6.Chand S, Paul B, Kumar M. An overview of use of Linz-Donawitz (LD) steel slag in agriculture. Current World Environment: An International Research Journal of Environmental Sciences. 2015;10(3):975-984. DOI: 10.12944/CWE.10.3.29
7.Proctor DM et al. Physical and chemical characteristics of blast furnace, basic oxygen furnace, and electric arc furnace steel industry slags. Environmental Science & Technology. 2000;34:1576-1582
8.Singh R, Gorai AK, Segaran RG. Characterisation of LD slag of Bokaro steel plant and its feasibility study of manufacturing commercial ‘fly ash-LD slag’ bricks. International Journal of Environmental Technology and Management, Inderscience Enterprises Ltd. 2013;16(1/2):129-145
9.Mahieux PY, Aubert JE, Escadeillas G. Utilization of weathered basic oxygen furnace slag in the production of hydraulic road binders. Construction and Building Materials. 2009;23:742-747
10.Wu S, Xue Y, Ye Q, Chen Y. Utilization of steel slag as aggregates for stone mastic asphalt (SMA) mixtures. Building and Environment. 2007;42:2580-2585
11.Xue Y, Wu S, Hou H, Zha J. Experimental investigation of basic oxygen furnace slag used as aggregate in asphalt mixture. Journal of Hazardous Materials. 2006;138:261-268
12.Lim JW, Chew LH, Choong TSY, Tezara C, Yazdi MH. Overview of steel slag application and utilization. MATEC Web of Conferences. 2016;74:00026. DOI: 10.1051/matecconf/20167400026
13.Xian W, Qing-Sheng CAI. Steel slag as an iron fertilizer for corn growth and soil improvement in a pot experiment, project supported by the National Natural Science Foundation of China (No. 30270800). Pedosphere. 2006;16(4):519-524. ISSN 1002-0160. DOI: 10.1016/S1002-0160(06)60083-0
14.Ning D, Liang Y, Liu Z, Xiao J, Duan A. Impacts of steel-slag-based silicate fertilizer on soil acidity and silicon availability and metals-immobilization in a paddy soil. PLoS One. 2016;11(12):e0168163. DOI: 10.1371/journal.pone.0168163
15.Yi H, Xu G, Cheng H, Wang J, Wan Y, Chen H. An overview of utilization of steel slag. Procedia Environmental Sciences. 2012;16:791-801
16.Branca TA, Colla V. Possible uses of steelmaking slag in agriculture: An overview. In: Achilias D, editor. Material Recycling - Trends and Perspectives. London: InTechOpen; 2012. ISBN: 978-953-51-0327-1
17.Ashrit S, Banerjee PK, Chatti RV, Rayasam V, Nair UG. Synthesis and characterization of Dhurvi Gold from LD slag fines generated in a steel plant. Current Science. 2015;109:727-732
18.Higson GI. CaSO4 as a raw material for chemical manufacture. Chemical and Engineering News. 1951;29:4469-4474
19.Zivanovic V. Analysis of Plant Available Nutrients by use of ICP-MS, ICP-OES and MP-AES- Simplifying the Analytical Approach in Everyday Analysis. Norway: Norwegian University of Life Sciences; 2017. DOI: 10.13140/RG.2.2.16204.41602
20.Waligora J, Bulteel D, Degrugilliers P, Damidot D, Potdevin JL, Measson M. Chemical and mineralogical characterizations of LD converter steel slags: A multi-analytical techniques approach. Materials Characterization. 2010;61:39-48
21.Kourounis S, Tsivilis S, Tsakiridis PE, Papadimitriou GD, Tsibouki Z. Properties and hydration of blended cements with steelmaking slag. Cement and Concrete Research. 2007;37:815-822
22.Miller WP, Radcliffe DE, Sumner ME. The effect of soil amendment with phosphogypsum on clay dispersion, soil conservation and environmental quality. In: Proceedings of the Second International Symposium on Phosphogypsum, Miami. Bartow, Florida: Florida Institute of Phosphate Research; 1986
23.Beretka J, Cioffi R, Marroccoli M, Valenti GL. Energy saving cements obtained from chemical gypsum and other industrial wastes. Waste Management. 1996;16:231-235
24.Pavan MA, Bingham FT. Effects of phosphogypsum and lime on yield, root density, and fruit and foliar composition of apple in Brazilian acid soils. In: Proceedings of the Second International Symposium on Phosphogypsum, Miami, FL. 1986
25.Laxmanarayanan M, Dhumgond P, Shruthi, et al. Influence of Dhurvi Gold on nutrient uptake and yield of groundnut in different acid soils of southern India. Scientific Reports. 2022;12:5604. DOI: 10.1038/s41598-022-09591-1
26.Ashrit S, Chatti RV, Udpa KN, Venugopal R, Nair UG. Process optimization of Dhurvi Gold synthesized from LD slag fines – An opportunity for value addition of LD slag. Metallurgical Research & Technology. 2016, 2016;113(6):605. DOI: 10.1051/metal/2016037
27.Macsik J, Jacobsson A. Leachability of V and Cr from LD slag/Portland cement stabilized sulphide soil. Waste Management. 1996;16:699-709
28.Das S, Kim GW, Hwang HY, Verma PP, Kim PJ. Cropping with slag to address soil, environment, and food security. Frontiers in Microbiology. 2019;10:1320. DOI: 10.3389/fmicb.2019.01320
29.Das S, Gwon HS, Khan MI, et al. Steel slag amendment impacts on soil microbial communities and activities of rice (Oryza sativa L.). Scientific Reports. 2020;10:6746. DOI: 10.1038/s41598-020-63783-1
30.Yang L, Wei T, Li S, Lv Y, Miki T, Yang L, et al. Immobilization persistence of Cu, Cr, Pb, Zn ions by the addition of steel slag in acidic contaminated mine soil. Journal of Hazardous Materials. 2021;412:125176. ISSN 0304-3894. DOI: 10.1016/j.jhazmat.2021.125176
Open access peer-reviewed chapter
