Abstract
The effective utilization of slag fertilizer in agriculture to neutralize soil acidity, improve crop productivity, mitigate greenhouse gas emissions, and stabilize heavy metals in contaminated soils turns it into a high value added product in sustainable agriculture. These effects could be due to the shift in microbial metabolism and/or modification of microbial habitats. At the system level, soil microorganisms play an integral role in virtually all ecosystem processes. There is a growing interest to reveal the underlying mechanisms of slag-microbe interactions and the contribution of soil biota to ecosystem functioning. In this perspective, we discuss the possible driving mechanisms of slag-microbe interactions in soil and how these slag-microbe interactions can affect crop yield, greenhouse gas emissions, soil carbon sequestration, and heavy metal stabilization in contaminated soils. In addition, we discuss the problems and environmental concerns in using slag in agriculture. Emphasis has been given for further research to validate the proposed mechanisms associated with slag-microbe interactions for increasing soil quality, crop productivity, and mitigating environmental consequences. While evaluating the slag amendment, effects on agriculture and environment, the potential risks, socio-economics, techno-economics, and ethics should be assessed.
Highlights
Over the past decades, with the rapid growth of industrialization, the higher volume of byproducts generated from iron/steel production draw attention to the need for its recycling in an increasingly efficient way
The influence of slag fertilizer on the soil microbiome are diverse and the possible mechanisms of slagmicrobes interactions can be as follows: (1) slag fertilizer supplies nutrients to the plant and to soil microorganisms; (2) slag fertilizer modifies soil microbial habitats by improving soil properties (Gwon et al, 2018), which is essential for nutrient mobilization and microbial growth; (3) silicate fertilizer increases plant photosynthesis (Detmann et al, 2012) and likely increases belowground carbon allocation through root exudates, which eventually triggers soil microbial proliferation and activities; and (4) steel slag enhances heavy metal immobilization in soil (Ning et al, 2016) and reduces their bioavailability and toxicity to microbes
Steel-making processes were exclusively designed for the production of specific quality and quantities of iron and steel, one of today’s goals for steel making is to design and develop technologies to produce high-quality slag according to the market requirements
Summary
With the rapid growth of industrialization, the higher volume of byproducts (slag) generated from iron/steel production draw attention to the need for its recycling in an increasingly efficient way. Several studies have revealed that the slag-based fertilizer amendment in agriculture has great promise to improve crop productivity (White et al, 2017; Gwon et al, 2018), alleviate soil acidification (Ning et al, 2016), mitigate greenhouse gas (GHG) emissions (Wang et al, 2015; Gwon et al, 2018), and stabilize heavy metals in contaminated soils (Ning et al, 2016), which turns it into a high value added product for sustainable agriculture.
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