Microbial response to designer biochar and compost treatments for mining impacted soils

Phosphorus fertilizer: from commodity to speciality - from fertilizing the field to fertilizing the plant

Phosphatic fertilizers are indispensable for sustainable agriculture, but phosphorus (P) scarcity has drawn global attention with respect to research and policy discussions. Soil conditions (pH, organic matter, metal oxides), P-fertilizer form and its application methods, and plant growth mechanisms influence plant P availability. Given the nonrenewable nature and low use efficiency of P, the development of speciality P-fertilizers and improved application methods are essential for reducing environmental P losses and increasing plant P uptake, thereby improving P use efficiency (PUE). This paper explores strategies for using innovative P-fertilizers targeting plant physiological processes instead of conventional bulk field applications to enhance PUE.

Utilization of current pyrolysis technology to convert biomass and manure waste into biochar for soil remediation: A review

Traditional disposal of animal manures and lignocellulosic biomass is restricted by its inefficiency and sluggishness. To advance the carbon management and greenhouse gas mitigation, this review scrutinizes the effect of pyrolysis in promoting the sustainable biomass and manure disposal as well as stimulating the biochar industry development. This review has examined the advancement of pyrolysis of animal manure (AM) and lignocellulosic biomass (LB) in terms of efficiency, cost-effectiveness, and operability. In particular, the applicability of pyrolysis biochar in enhancing the crops yields via soil remediation is highlighted. Through pyrolysis, the heavy metals of animal manures are fixated in the biochar, thereby both soil contamination via leaching and heavy metal uptake by crops are minimized. Pyrolysis biochar is potentially use in soil remediation for agronomic and environmental co-benefits. Fast pyrolysis assures high bio-oil yield and revenue with better return on investment whereas slow pyrolysis has low revenue despite its minimum investment cost because of relatively low selling price of biochar. For future commercialization, both continuous reactors and catalysis can be integrated to pyrolysis to ameliorate the efficiency and economic value of pyrolysis biochar.

The effects of biochar and its applications in the microbial remediation of contaminated soil: A review

The amendment of biochar for soil bioremediation can improve soil conditions, influence soil microbial community, and achieve co-application of biochar-microbe to promote the removal of pollutants. This paper summarizes the positive effects of biochar on microorganisms, including acting as a shelter, providing nutrients, and improving soil conditions (soil aggregation, pH, cation exchange capacity (CEC), and enzymatic activity). These effects will cause variations in microbial abundance, activity, and community structure. Biochar can act as an electron mediator to promote electron transfer in the process of microbial degradation. And the application of biochar in soil bioremediation is also introduced. Nevertheless, toxic substances carried by biochar that may threaten microbial community shouldn't be overlooked. With this review, we can better understand biochar's involvement in soil bioremediation, which will help us choose and modify biochar in a targeted manner for the desired purpose in practical applications.

Effects of Biochar-Based Fertilizers on Energy Characteristics and Growth of Black Locust Seedlings

To understand ecological and energy problems in the karst area of Guizhou, China, the effects of using biochar-based fertilizers on the energy characteristics of different species of black locust were studied. To determine the most suitable species and the best rational application method of biochar, an outdoor pot experiment was performed using three species of black locust (White-flowered locust (W), Hong-sen locust (S), and Large-leaf fast-growing locust (L)). There were six treatments: control (CK), MF, RH2MF, RH4MF, W2MF, and W4MF (M—compost; F—NPK fertilizer; RH—rice husk biochar; and W—wood biochar), where the numbers represented the mass ratio of biochar to soil. Biochar-based fertilizers had significant effects on the total organic carbon (TOC), total nitrogen (TN), total potassium (TK), branch gross calorific values (GCV), and ash removal calorific values (AFCV) of seedlings. RH4MF had the best overall values. Different species had significant effects in all indicators (except for TN); the effect on S was better than that of W and L. Principal component analysis showed that RH4MF-S had the highest comprehensive scores. In summary, Hong-sen locust (S) was a high-quality energy species and RH4MF may be used as fertilization for energy forest development. This study provides a reference for future long-term energy forest research in this area.

Microbial Response to Phytostabilization in Mining Impacted Soils Using Maize in Conjunction with Biochar and Compost

Even after remediation, mining impacted soils can leave behind a landscape inhospitable to plant growth and containing residual heavy metals. While phytostabilization can be used to restore such sites by limiting heavy metal spread, it is reliant on soil capable of supporting plant growth. Manure-based biochars, coupled with compost, have demonstrated the ability to improve soil growth conditions in mine impacted soils, however there is a paucity of information regarding their influence on resident microbial populations. The objective of this study was to elucidate the impact of these soil amendments on microbial community structure and function in mine impacted soils placed under phytostabilization management with maize. To this aim, a combination of phospholipid fatty acid (PLFA) and enzymatic analyses were performed. Results indicate that microbial biomass is significantly increased upon addition of biochar and compost, with maximal microbial biomass achieved with 5% poultry litter biochar and compost (62.82 nmol g-1 dry soil). Microbial community structure was impacted by biochar type, rate of application, and compost addition, and influenced by pH (r2 = 0.778), EC (r2 = 0.467), and Mg soil concentrations (r2 = 0.453). In three of the four enzymes analyzed, poultry litter biochar treatments were observed with increased activity rates that were often significantly greater than the unamended control. Overall, enzyme activities rates were influenced by biochar type and rate, and addition of compost. These results suggest that using a combination of biochar and compost can be utilized as a management tool to support phytostabilization strategies in mining impacted soils.