Biochar Amendments Influence Root Rot of Soybeans Caused by Fusarium Virguliforme and Phytophthora Sojae.

Recent studies have suggested that biochar applications may suppress certain foliar fungal diseases and pests of tomato and pepper, and root rot disease of asparagus.  Some researchers attributed this fungal disease suppressive effect of biochar to induction of systemic resistance in plants. The objective of this greenhouse study was to evaluate the effect of various types of biochars on sudden death syndrome and Phytophthora root rot severity of soybeans. A set of eight biochars that differ in feedstock, pyrolitic temperature and pyrolysis process were selected for evaluation and included three slow pyrolysis biochars produced from corn stover at 400, 500, and 600°C; two fast pyrolysis biochars produced from corn stover and oak at 500°C; and three hardwood biochar commercially produced by gasification, slow, and fast pyrolysis.  A silty clay loam soil was mixed with various biochars in the rate of 2% and with F. virguliforme-infested sorghum and P. sojae-infested rice inocula. Controls of no biochar, non-infected rice and sorgum were also included for a total of 36 treatments replicated four times. Soil was packed into pots and incubated for 10 weeks with weekly watering to allow the soil-biochar systems to equilibrate.  Soil moisture content was monitored periodically by weighing pots 24 hours after watering.  On week 11th, soybeans were planted in the pots and grown for period of 4 weeks at which time the plants and roots were excavated and disease severity and soybean root health was visually assessed. Detailed results will be presented.