DEVELOP AND IMPROVE STRATEGIES FOR MANAGEMENT OF IRRIGATED AGRICULTURAL CROPS AND SOILS
Location: Northwest Irrigation and Soils Research
Title: Biochar: A soil amendment worth considering
Submitted to: University of Idaho Miscellaneous Publication
Publication Type: Popular Publication
Publication Acceptance Date: November 18, 2009
Publication Date: December 10, 2009
Citation: Ippolito, J.A., Lentz, R.D., Novak, J.M. 2009. Biochar: A soil amendment worth considering. University of Idaho Miscellaneous Publication. 2(2):1-2.
Biochar is a fine-grained, carbon enriched product created when biomass (e.g. wood waste, manures) is burned at relatively low temperatures (less than 1300oF) and under an anoxic (lack of oxygen) atmosphere. The benefits of biochar addition to soils have long since been recognized. Amazonian dark earth soils, also known as terra preta, are charcoal-enriched soils containing a high nutrient content from reduced leaching, likely a response of human-induced biochar accumulation. These soils, dating to between 450 BC and 950 AD, are unique to the Amazon region as most tropical soils are highly weathered and thus generally infertile. Scientists are now attempting to reproduce this technology by using biochar-type products as soils supplements. Research by the newly formed USDA-Agricultural Research Service’s National Biochar Initiative is directed at using biochar in soils across the US. Scientists at the USDA-ARS in Florence, SC have found that a 2% biochar application (approximately 40 to 44 tons/ac) can increase soil water holding capacity of silt loam soils (such as those found in Idaho) as compared to controls. This means that more water is available to the plant for a longer period of time. Additional benefits such as reduced nutrient leaching are currently being investigated by ARS scientists from SC and ID. First-year results from long-term field trials at the Kimberly, ID ARS location indicated that 10 tons/acre of biochar increased soil carbon concentrations and available manganese relative to controls, and either had no effect or decreased emission of greenhouse gases compared to controls. Biochar also interacted positively with manure to increase availability of soil nitrogen, phosphorus, and zinc. Another long-term study added 1 or 2% biochar to an eroded calcareous soil to evaluate effects on soil properties and plant nutrient uptake. Bean was grown during the first year, and biochar effects on nutrient uptake were minimal. Results of a separate, four-month incubation study suggested that biochar application (up to 10% by weight) to eroded calcareous soil can decrease nitrate-nitrogen concentrations and increase plant-available iron, manganese, nickel, and zinc. Marked increases in soil organic carbon content was observed, as was expected when applying an organic carbon source such as biochar.