Biochar amendment improves crop production in problem soils: A review

Problem soils are referred to as those with poor physical, chemical, and biological properties that inhibit or prevent plant growth. These poor properties may be a result of soil formation processes but are largely due to inappropriate farming practices or anthropogenic pollution. The world has lost a third of its arable land due to erosion and pollution in the past 40 years. Thus, there is an urgent need for improving and remediating problem soils. As a novel multifunctional carbon material, biochar has been widely used as a soil amendment for improving soil quality. Previous reviews have summarized the characteristics of biochar, the interactions with various soil contaminants, and the effects on soil quality, soil productivity, and carbon sequestration. Relatively limited attention has been focused on the effects of biochar amendment on plant growth in problem soils. As a result, a comprehensive review of literature in the Web of Science was conducted with a focus on the effects of biochar amendment on plant growth in problems soils. The review is intended to present an overview about problem soils, biochars as functional materials for soil amendment, how amended biochars interact with soils, soil microbes, and plant roots in remediation of problem soil and improve plant growth. Additionally, existing knowledge gaps and future directions are discussed. Information gathered from this review suggests that biochar amendment is a viable way of improving the quality of problem soils and enhancing crop production. It is anticipated that further research on biochar amendment will increase our understanding on the interactions of biochar with components of problem soils, speed up our effort on soil remediation, and improve crop production in problem soils.