A Critical Review on Advancement and Challenges of Biochar Application in Paddy Fields: Environmental and Life Cycle Cost Analysis

Abstract

Paddy fields emit considerable amounts of methane (CH4), which is a potent greenhouse gas (GHG) and, thereby, causes significant environmental impacts, even as they generate wealth and jobs directly in the agricultural sector, and indirectly in the food-processing sector. Application of biochar in rice production systems will not just help to truncate their carbon footprints, but also add to the bottom-line. In this work, the authors have reviewed the literature on climate change, human health, and economic impacts of using organic residues to make biochar for the addition to croplands especially to rice paddy fields. Biochar-bioenergy systems range in scale from small household cook-stoves to large industrial pyrolysis plants. Biochar can be purveyed in different forms—raw, mineral-enriched, or blended with compost. The review of published environmental life cycle assessment (E-LCA) studies showed biochar has the potential to mitigate the carbon footprint of farming systems through a range of mechanisms. The most important factors are the stabilization of the carbon in the biochar and the generation of recoverable energy from pyrolysis gases produced as co-products with biochar as well as decreased fertiliser requirement and enhanced crop productivity. The quantitative review of E-LCA studies concluded that the carbon footprint of rice produced in biochar-treated soil was estimated to range from −1.43 to 2.79 kg CO2-eq per kg rice grain, implying a significant reduction relative to rice produced without a biochar soil amendment. The suppression of soil-methane emission due to the biochar addition is the dominant process with a negative contribution of 40–70% in the climate change mitigation of rice production. The review of the life cycle cost studies on biochar use as an additive in farmlands demonstrated that biochar application can be an economically-feasible approach in some conditions. Strategies like the subsidization of the initial biochar capital cost and assignment of a non-trivial price for carbon abatement in future pricing mechanisms will enhance the economic benefits for the rice farmers.

Overview of the Benefits and Challenges Associated with Pelletizing Biochar

“…Biochar has a broad range of applications including being used as a soil nutritional and liming agent, as construction material, as an adsorbent for wastewater treatment, or as a source of energy. The environmental and economic benefits from the use of biochar have been reported in recent studies [4][5][6]. However, in the midst of these numerous application potentials of biochar, challenges abound.…”

Comparative Life Cycle Assessment of Co-Processing of Bio-Oil and Vacuum Gas Oil in an Existing Refinery

“…To ensure the sustainable development of society, developing renewable fuels with less CO 2 emission is of vital significance considering the lack of fossil resources and the greenhouse effect [1]. Developing bio-fuels can serve for solving the resource shortage issue as well as easing environmental burden [2].…”

Sustainable management of paddy crop residues: effects on methanotrophs diversity and value for soil health restoration

“…With the intervention of some eco‐friendly agricultural practices such as the application of suitable soil amendments farmers can enhance methanotrophs community structure in aerobic paddy soils. Biochar can play a significant role in reducing CH 4 emissions in paddy soil by influencing the oxidation of CH 4 by methanotrophic bacteria (Davamani et al, 2020; Mohammadi et al, 2020; Nan et al, 2020; Singh et al, 2011). Therefore, rice husk biochar (RHB)‐based paddy cultivation can be a profitable and eco‐friendly practice to achieve igher rice production and CH 4 mitigation by enhancing the methanotrophs community structure and pmoA gene numbers in paddy soils.…”