Biochar Additions to Irrigated, Calcareous Soils: Effects On Soil Organic Carbon and Nutrient Availability.

Biochar, a charcoal created by pyrolysis of biomass, may be an effective means of storing carbon (C) in soils, but its effects on semiarid calcareous soils and irrigated crops are not well understood.  Compared to other organic amendments, we hypothesized that biochar additions would make nutrients more available to plants and store greater quantities of durable C in soils.  We initiated two long-term studies in Fall 2008 using hardwood derived biochar, 730 g kg^-1 C, 150 g kg^-1 ash:  1) In the field we studied biochar and/or manure amendment effects on N mineralization under sprinkler irrigated corn (Zea mays L.).  A Portneuf silt loam soil (0 to 15 cm) was treated with 10 g kg^-1 biochar, 10 g kg^-1 biochar plus 20 g kg^-1 dairy manure, or left untreated.  Soil C concentrations and N mineralization rates and uptake were measured annually.  2) In a pot study we compared the effect of biochar and other amendments on nutrient uptake by bean (Phaseolus vulgaris L.) in an eroded Portneuf silt loam soil prone to Fe and Zn deficiency.  The pot treatments included biochar, dairy manure, sawdust, and acidified sawdust, each applied at three rates of 0, 10, and 20 g kg^-1. Uptake of N, P, and K, and micronutrients Fe, Zn, Mn, and Cu by two bean varieties was measured.  Preliminary results will be presented and discussed.