Chicken Manure Biochar as Liming and Nutrient Source for Acid Appalachian Soil

Abstract

Acid weathered soils oft en require lime and fertilizer application to overcome nutrient defi ciencies and metal toxicity to increase soil productivity. Slow-pyrolysis chicken manure biochars, produced at 350 and 700oC with and without subsequent steam activation, were evaluated in an incubation study as soil amendments for a representative acid and highly weathered soil from Appalachia. Biochars were mixed at 5, 10, 20, and 40 g kg-1into a Gilpin soil (fi ne-loamy, mixed, active, mesic Typic Hapludult) and incubated in a climate-controlled chamber for 8 wk, along with a nonamended control and soil amended with agronomic dolomitic lime (AgLime). At the end of the incubation, soil pH, nutrient availability (by Mehlich-3 and ammonium bicarbonate diethylene triamine pentaacetic acid [AB-DTPA] extractions), and soil leachate composition were evaluated. Biochar eff ect on soil pH was processand rate-dependent. Biochar increased soil pH from 4.8 to 6.6 at the high application rate (40 g kg-1), but was less eff ective than AgLime. Biochar produced at 350oC without activation had the least eff ect on soil pH. Biochar increased soil Mehlich-3 extractable micro- and macronutrients. On the basis of unit element applied, increase in pyrolysis temperature and biochar activation decreased availability of K, P, and S compared to nonactivated biochar produced at 350oC. Activated biochars reduced AB-DTPA extractable Al and Cd more than AgLime. Biochar did not increase NO3 - in leachate, but increased dissolved organic carbon, total N and P, PO43-, SO42-, and K at high application rate (40 g kg-1). Risks of elevated levels of dissolved P may limit chicken manure biochar application rate. Applied at low rates, these biochars provide added nutritional value with low adverse impact on leachate composition. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.