|Laird, David - Iowa State University|
|Novak, Jeffrey - Jeff|
|Collins, Harold - Hal|
|Karlen, Douglas - Doug|
|Lentz, Rodrick - Rick|
|Van Pelt, Robert - Scott|
Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2016
Publication Date: 11/28/2016
Citation: Laird, D.A., Novak, J.M., Collins, H.P., Ippolito, J.A., Karlen, D.L., Lentz, R.D., Sistani, K.R., Spokas, K.A., Van Pelt, R.S. 2016. Multi-year and multi-location soil quality and crop biomass yield responses to hardwood fast pyrolysis biochar. Geoderma. 289:46-53. Interpretive Summary: Biochar is a man-made byproduct from the biofuel processing industry. It has received global attention as a soil amendment to improve carbon sequestration, fertility, and increase moisture retention. When biochar is added to very poor fertility soils, the literature reports significant improvements in crop yields and soil fertility characteristics. In view of the need to increase food production, however, it would be desirable if biochar applied to more fertile soils also increase crop yields. We conducted a multi-year, multi-location study across several locations where a hardwood biochar was applied to fertile soils and the crop productivity (grain and stover yields) along with soil organic carbon contents (SOC) were determined. As a comparison, soils at the locations were also treated with common inorganic fertilizers and manures. A corn and sorghum crop was grown and later the grain and stover yield were collected and weighed. After 3 years of experimentation, we found no significant improvement in the combined grain and stover yields after applying the biochar, manure, or inorganic fertilizer. We did find, however, a significant increase in SOC levels after treatment with this biochar. Overall, we concluded that this hardwood biochar produced by fast pyrolysis can be effective soil amendment for increasing SOC levels within the broad range of temperate soils at the multi-locations. On the other hand, crop yield responses should be anticipated only when a specific soil quality problem limits productivity.
Technical Abstract: Biochar can remediate degraded soils and maintain or improve soil health, but specific and predictable effects on soil properties and crop productivity are unknown because of complex interactions associated with climate patterns, inherent soil characteristics, site-specific crop and soil management practices, and the source, production characteristics, and amount of biochar applied. This multi-location field study was designed and conducted to determine if consistent response patterns could be elucidated by controlling the type and amount of biochar applied, depth of incorporation, and soil/crop management practices as much as possible for the six U.S. locations. When averaged for five locations, biochar or biochar plus manure (bio+man) treatments significantly (P<0.001) increased surface (0-15 cm) soil organic carbon (SOC) levels by 48 or 47%, respectively, relative to control treatments. The SOC levels for the manure only treatment were not significantly different from the control. No other measured soil properties showed significant biochar or biochar*manure interactions, even though applying manure significantly increased extractable potassium, magnesium, sodium, and phosphorus levels. Analysis of three years of pooled biomass yield data from the six locations showed a significant location effect (P<0.001), but treatment effects were not significant. However, dividing annual plot yields by the average for all control plots at each location created a dataset of relative yields that showed a significant location*treatment interaction and higher normalized yields (36%) due to biochar (P=0.017) at one of the six locations. Overall, we conclude that hardwood biochar produced by fast pyrolysis can be an effective soil amendment for increasing SOC levels within a broad range of temperate soils, but crop yield responses should be anticipated only when specific soil quality problems limit productivity.