Role of Nutrient-Enriched Biochar as a Soil Amendment during Maize Growth: Exploring Practical Alternatives to Recycle Agricultural Residuals and to Reduce Chemical Fertilizer Demand

Abstract

Recycling and value-added utilization of agricultural residues through combining technologies such as anaerobic digestion and pyrolysis could double the recoverable energy, close the nutrient recycle loop, and ensure cleaner agricultural production. This study assessed the beneficial application of biochar to soil to recycle digestate nutrients, improve soil quality, and reduce conventional chemical fertilizer. The addition of digestate-enriched biochar improved soil quality as it provided higher soil organic matter (232%–514%) and macronutrients (110%–230%) as opposed to the unenriched biochar and control treatments. Maize grown in soil amended with digestate-enriched biochar showed a significantly higher biomass yield compared to the control and non-enriched biochar treatments but was slightly lower than yields from chemical fertilizer treatments. The slightly lower yield (20%–25%) achieved from digestate-enriched biochar was attributed to slower mineralization and release of the adsorbed nutrients in the short term. However, digestate-enriched biochar could in the long term become more beneficial in sustaining soil fertility through maintaining high soil organic matter and the gradual release of micronutrients compared to conventional chemical fertilizer. Positive effects on soil micronutrients, macronutrients, organic matter, and biomass yield indicates that enriched biochar could partly replace chemical fertilizers and promote organic farming in a circular economy concept.

Enhancing soil water holding capacity and provision of a potassium source via optimization of the pyrolysis of bamboo biochar

“…Chemical adsorption is considered as the second most influential parameter for water holding capacity of the biochar (Batista et al 2018;Kizito et al 2019). Between 600-2 and 800-1 products, 800-1 showed the significant increase in BET surface area, no difference in TPV (Fig.…”

Role of biochar in promoting circular economy in the agriculture sector. Part 1: A review of the biochar roles in soil N, P and K cycles

“…In general, increased soil CEC gained by the application of biochar, due to its structural properties such as porous structure, large surface area and negative surface charge, tends to strengthen the retention of K and enable the slow release of nutrients [105]. Kizito et al [106] examined the effect of soil application of corn cob and wood biochar saturated with an anaerobic digestate (AD) derived from biomethanol production. They observed that the application of AD-enriched wood biochar to clay loam soil at a rate of 20 t ha −1 increased soil CEC by > 300%, which were accompanied with a significant increase in the soil macronutrient contents including K, and aboveground biomass of cultivated maize plants.…”

Innovative Processes and Technologies for Nutrient Recovery from Wastes: A Comprehensive Review

“…Biochar application can increase the carbon content in soil and help in carbon sequestration to improve soil and environment quality ( Figure 5). Moreover, biochar can also enrich soil with nutrients by improved recycling [65][66][67]. About more than half of the nitrogen, phosphorus, and potassium can also be recovered [20].…”