Soil Nutrients and Carbon Dynamics in the Presence of Biochar-swine Manure Mixture Under Controlled Leaching Experiment Using a Midwestern USA Soil

Abstract

Biochar application to the soil can improve soil quality and nutrient leaching loss. Recent studies have reported that surficial application of biochar to stored swine manure can reduce emissions of odorous compounds and reduce the volatilization loss of ammonia. Our working hypothesis was that the biochar-treated manure application to the soil would decrease nutrient leaching from manure and increase plant-available nutrients. The study objectives were to evaluate the impact of biochar-treated swine manure on soil total C, N, and other major and minor nutrients. Three biochars (i) neutral pH red-oak (RO), (ii) highly alkaline autothermal corn (Zea mays) stover (HAP), and (iii) mild acidic Fe-treated autothermal corn stover (HAPE) were incubated with swine manure for a month. The biochar-manure mixture was applied in triplicate to soil columns with application rate determined by the P2O5-P content in manure or manure-biochar mixtures after the incubation. The ammonium (NH4+), nitrate (NO3-), and reactive P concentrations in soil column leachates were recorded for eight leaching events. Soil properties and plant-available nutrients were compared between treatments and control manure & soil. Manure-(HAP&HAPE) biochar treatments significantly increased soil organic matter (OM) and increased soil total C, N, and improved soil bulk density. Concentrations of KCl-extractable NH4+ and NO3- significantly increased in HAPE column leachates during this 4-week study and in the soil after the experiment. A significant reduction in soil Mehlich3 Cu was also observed for the manure-HAPE mixture compared with the control. Overall, the manure-biochar incubation enabled biochar to sorb nutrients from manure, and the subsequent manure-biochar mixture application to soil improved soil quality and plant nutrient availability in comparison to conventional manure application to soil. This proof-of-the-concept study suggests that biochars could be used to solve both environmental and agronomic challenges and further improve the sustainability of animal and crop production agriculture.

Reduction of gaseous emissions from swine manure: effect of biochar dose and reapplication

“…There is an opportunity to further explore short-term biochar application to stored manure immediately prior to agitation and pumpout. We already showed significant % reductions of NH3 and H2S emissions during the swine manure agitation (Chen et al, 2021b;Banik et al, 2021). Testing of biochar addition on mitigating of odor and odorous VOCs emissions during agitation, pumpout, and land application is warranted.…”

“…Enhanced generation of biogas (and its main component, CH4) from biochar-treated manure could provide additional options for biorenewable energy production on a farm biogas plant. Furthermore, the biochar and manure mixture has shown the potential to be better fertilizers and helping to stop leaching (Banik et al, 2021). In addition, biochar treatment of manure from other types of livestock & poultry and other gaseous emissions sources such as municipal and industrial wastewater and landfills could be explored.…”

Mitigation of acute H2S and NH3 emissions from swine manure during agitation using pelletized biochar

“…We have been advancing the use of carbon-rich adsorbent (biochar) as a manure treatment to mitigate gaseous emissions from stored manure (Chen et al, 2021a). Biochar is a by-product of the thermal processing of biomass.…”

“…Biobased-fuels production, waste-to-carbon, and waste-to-energy thermal processes result in a relatively low-value biocoal. Circular economy opportunities exist for the valorization of biochar and the improvement of sustainability in animal and crop production systems (Banik et al, 2021a;Banik et al, 2021b). The long-term goal is to test and scale up the treatments from laboratory-scale to farm-scale, keeping in mind the techno-economic constraints for many swine farmers.…”

“…Biochar powder is the simplest form of biochar generated in typical pyrolysis. Biochar powder effectively mitigates emissions of H2S and NH3 for both long-term (weeks to months) (Meiirkhanuly et al, 2020;Chen et al, 2021a) and short-term (few minutes) trials (Chen et al, 2020b;Chen et al, 2020c). Chen et al reported up to 60% reduction in H2S emissions and 70 to 80% reduction in NH3 emissions by surficial biochar powder application immediately before 3-min manure agitation (Chen et al, 2020b;Chen et al, 2020c).…”