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United States Department of Agriculture

Agricultural Research Service

Research Project: Improving Nutrient Utilization in Western Irrigated Crop Production Systems

Location: Northwest Irrigation and Soils Research

Title: Hardwood biochar influences calcareous soil physicochemical and microbiological status

Authors
item IPPOLITO, JAMES
item Stromberger, M.E. -
item LENTZ, RODRICK
item DUNGAN, ROBERT

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 2013
Publication Date: January 24, 2014
Repository URL: http://handle.nal.usda.gov/10113/58619
Citation: Ippolito, J.A., Stromberger, M., Lentz, R.D., Dungan, R.S. 2014. Hardwood biochar influences calcareous soil physicochemical and microbiological status. Journal of Environmental Quality. 43(2):681-689.

Interpretive Summary: A hardwood-based, fast pyrolysis biochar was applied (0, 1, 2, and 10% by weight) to a calcareous soil, with changes in soil chemistry, water content, microbial respiration, and microbial community structure were monitored over a 12-month period. Increasing biochar application rate improved the soil water status, increased plant-available iron and manganese, soil carbon content, soil respiration rates, bacterial populations, and decreased soil nitrate-nitrogen concentration. The 10% biochar application rate caused the greatest change in microbial community structure, a physiological response to stress, and a drastic reduction in soil nitate-nitrogen, and thus would not be recommended for production agricultural settings.

Technical Abstract: The effects of biochar application to calcareous soils are not well documented. In a laboratory incubation study, a hardwood-based, fast pyrolysis biochar was applied (0, 1, 2, and 10% by weight) to a calcareous soil. Changes in soil chemistry, water content, microbial respiration, and microbial community structure were monitored over a 12-month period. Increasing biochar application rate increased the water holding capacity of the soil-biochar blend, a trait that could be beneficial under water limited situations. Biochar application also caused an increase in plant-available iron and manganese, soil carbon content, soil respiration rates, bacterial populations, and a decrease in soil nitrate-nitrogen concentration. Biochar rates of 2 and 10% altered the relative proportions of bacterial and fungal fatty acids, and shifted the microbial community towards greater relative amounts of bacteria and less fungi. The ratio of fatty acid 19:0 cy to its precursor, 18:1'7c, was higher in 10% biochar rate soil than all other soils, potentially indicating an environmental stress response. The 10% application rate of this particular biochar was extreme, causing the greatest change in microbial community structure, a physiological response to stress in Gram-negative bacteria, and a drastic reduction in soil nitate-nitrogen (85-97% reduction compared to the control), all of which were sustained over time.

Last Modified: 9/29/2014
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