INCUBATION STUDIES OF BIOCHAR AND MANURE TO MITIGATE CARBON DIOXIDE RELEASE AND NITROGEN DEFICIENCY IN SEMI-ARID SOILS

Abstract

Biochar (BC), produced through pyrolysis of organic residues, is increasingly being used as a beneficial soil amendment. We studied the effects of BC and animal manure additions on carbon dioxide (CO2) release and nitrogen (N) dynamics in three semi-arid climate soils. The objective of this study was to understand how BC application modifies soil nitrogen dynamics and moderate the effects of manure application in semi-arid agricultural systems on different textured soils: the loamy sand (LS) soil, the silty loam (SL) soil, and the clay loam (CL) soil. We found the positive interaction of BC and manure with BC suppressing CO2 emissions in manure amended soils. BC increased nitrogen mineralization in manure-amended soils towards the end of the incubation period 28 days. No significant N immobilization was observed in unamended soils. BC and manure soil additions reduced N deficiencies in all three soils. A second study focused on measuring carbon dioxide emissions from biochar-amended alkaline semi-arid soil. The objective of this study was to test if acidified and non-acidified BC released the same amount of CO2. The results showed that the soil samples amended with acidified BC released more CO2 than those amended with untreated BC with high alkalinity. It is postulated that untreated BC could absorb CO2; whereas, acidified BC with no alkalinity could not. The LS soil amended with BC released less CO2 than LS soil control perhaps due to the soil microbial activity inhibitory effects of the BC’s residual water soluble polynuclear aromatic hydrocarbons. Thus, the interaction with BC and steer manure application could suppress the release of CO2.