Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2011
Publication Date: 7/1/2012
Citation: Hass, A., Gonzalez, J.M., Lima, I.M., Godwin, H.W., Halvorson, J.J., Boyer, D.G. 2012. Chicken manure biochar as liming agent and nutrient source for acid Appalachian soil. Journal of Environmental Quality. 41:1096-1106. Interpretive Summary: Acid and highly weathered soils often require lime and fertilizer application to overcome nutrient deficiencies and metal toxicity in order to increase soil productivity. Biochar, a charcoal-like byproduct from the pyrolysis of biomass, can be used as soil amendment to improve the fertility of acid soils. Chicken manure biochar produced at different conditions was studied for effects on soil properties that are related to productivity and environmental welfare of a typical weathered acid soil from Appalachia. The soil + biochar (different types and application rates) along with a soil + agricultural lime and soil alone were incubated for 8-weeks. At the end of the experiment, soils were analyzed for pH, plant nutrients, and toxic metals. Biochar increased soil pH and was more effective than lime in increasing the availability of plant nutrients and in decreasing toxic metals. However, the use of biochar from chicken manure as a sole source of liming is inadequate since application rate would need to be 12 times greater than agricultural lime to achieve the same pH that lime application did. Biochar however provided added plant nutritional value and it can reduce mobility of toxic metals.
Technical Abstract: Acid and highly weathered soils often require lime and fertilizer application to overcome nutrient deficiencies and metal toxicity in order to increase soil productivity. Slow-pyrolysis chicken manure biochars, produced at 350 deg C and 700 deg C with and without subsequent steam-activation, were evaluated in an incubation study as liming agents and soil amendments for a representative acid and highly weathered soil from Appalachia. Biochars were mixed at 5, 10, 20, and 40 g kg-1 (by weight) into a Gilpin soil (Fine-loamy, mixed, active, mesic Typic Hapludults) and incubated in a climate-controlled chamber for eight weeks, along with a non-amended control and soil amended with agronomic dolomitic lime (AgLime). At the end of the incubation, soil pH, nutrient availability (by Mehlich-3, and AB-DTPA extractions), and soil leachate composition were evaluated. Biochar effect on soil pH was process-, and rate-dependent. Biochar increased soil pH from 4.8 to 6.6, at the high application rate (40 g kg-1), but was less effective than AgLime, which increased soil pH to a similar level (6.4) at much lower application rate (3 g kg-1). Biochar produced at 350 deg C without activation had the least effect on soil pH. Biochar increased Mehlich-3 extractable micro- and macro-elements, and activated biochars reduced AB-DTPA extractable Al, Cd, and Pb more than AgLime. Biochar did not increase NO3- in leachate, but at high application rate (40 g kg-1) it increased dissolved organic matter, total N and P, SO42- and K in leachate. When applied to a Gilpin soil, biochar increased soil pH, improved plant nutrient availability, and reduced levels of AB-DTPA extractable toxic and non-essential elements. At low application rates, steam-activated chicken litter biochars provide added nutritional value and low adverse impact on leachate composition.