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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #313787

Title: Predicting the impact of biochar additions on soil hydraulic properties

item Spokas, Kurt
item LIM, TAE JUN - Rural Development Administration - Korea
item Feyereisen, Gary
item Novak, Jeffrey

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2015
Publication Date: 4/17/2015
Citation: Spokas, K.A., Lim, T., Feyereisen, G.W., Novak, J.M. 2015. Predicting the impact of biochar additions on soil hydraulic properties [abstract]. Geophysical Research Abstracts. 17:EGU2015-6806.

Interpretive Summary:

Technical Abstract: Different physical and chemical properties of biochar, which is made out of a variety of biomass materials, can impact water movement through amended soil. The objective of this research was to develop a decision support tool predicting the impact of biochar additions on soil saturated hydraulic conductivity (Ksat). Four different kinds of biochar were added to four different textured soils (coarse sand, fine sand, loam, and clay texture) to assess these effects. Particle size distribution of each biochar was measured prior to soil mixing at the rates of 0, 1, 2, and 5 % (w/w). The results showed that the Ksat of the biochar amended soils were significantly influenced by the rate and type of biochar, as well as the original particle size of soil. The Ksat decreased when biochar was added to coarse and fine sands, as a function of the biochar rate. Biochar with larger particles sizes (60%; >1 mm) decreased Ksat to a larger degree than the smaller particle size biochar (60%; <1 mm) in the two sandy textured soils. Biochar additions reduced the bulk density (P<0.05) and similarly reduced Ksat for sandy soils (P<0.05). The increasing tortuosity in the amended sandy soil could explain this behavior. On the other hand, for the clay loam 1% and 2% biochar additions universally increased the Ksat with higher biochar amounts (up to 5%) providing no further alterations. The developed model utilizes soil texture pedotransfer functions for predicting agricultural soil Ksat as a function of soil texture. The model accurately predicted the direction of the Ksat influence, even though the exact magnitude still requires further refinement. This represents the first step to a unified theory behind the impact of biochar additions on soil saturated conductivity.