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Title: Phosphorus distribution in soils treated with bioenergy co-product materials following corn growth

item PAGLIARI, PAULO - University Of Minnesota
item STROCK, JEFFREY - University Of Minnesota
item Johnson, Jane
item Waldrip, Heidi

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2018
Publication Date: 4/12/2018
Publication URL:
Citation: Pagliari, P.H., Strock, J.S., Johnson, J.M., Waldrip, H. 2018. Phosphorus distribution in soils treated with bioenergy co-product materials following corn growth. Agronomy Journal. 110(3):850-858. doi:10.2134/agronj2017.04.0239.

Interpretive Summary: Plant biomass or animal manure can be used as energy feedstocks for producing heat, electricity, biooil or biogas. Combustion is burning with adequate oxygen; the co-product is ash, which has value as phosphorus fertilizer. Unlike combustion, gasification occurs with reduced oxygen and pyrolysis occurs at very low oxygen levels; therefore, instead of ash, a co-product call biochar is left behind. Biochar properties vary depending upon the feedstock. Gasification and pyrolysis of these feedstock as yet are not a common practices, but are anticipated to increase as clean, renewable and environmentally-friendly alternatives to fossil fuels. We wanted to know if the biochar had value as a phosphorus fertilizer, because it could be sold as a second product (energy being the first product). In this study, we used ash made from burning turkey manure, biochar made by gasifying corn cob mixed with wood and a biochar made from pyrolyzed switchgrass. We compared if they behaved in soil like a phosphorus fertilizer. The results of this study showed that application of two different biochars and the turkey manure to supply nutrients was similar to ordinary inorganic fertilizer. In general it appears biochar may have value as a fertilizer. This information will benefit the developing bioenergy industry, crop consultants and crop producers.

Technical Abstract: Biochar is a carbonaceous co-product that results from pyrolysis of organic material in the absence of oxygen produced for use as a soil amendment. Pyrolysis, gasification, and combustion are three processes being investigated and/or used to convert biomass into renewable energy and other products. This research was conducted to compare how the addition of two biochars [corn cob gasification biochar (CCGB), switchgrass pyrolysis biochar (SPB)], ordinary triple superphosphate fertilizer (TSP), and ash resulting from a turkey manure combustion facility (TMA) would impact the soil P chemical distribution in three soil series used for agricultural production in the west central, central, and southwest regions in Minnesota, US. Amendments were applied at P rates of 28, 56 and 84 mg P kg-1; however, specific mass of amendment applied varied significantly among treatments because of differences in total P concentrations of the TSP, TMA, SPB, and CCGB. Corn (2 pot-1) and wheat (10 pot-1) plants were grown for 56 days after emergence and soil samples were collected for P chemical sequential fractionation in water, 0.5M NaHCO3, 0.1M NaOH, 1.0M HCl. The changes in soil P pools that were observed in this study were likely due to the changes in soil pH. The use of CCGB increased the concentration of labile (H2O and NaHCO3-soluble) total P while decreasing the concentration of NaOH soluble total P. The TMA was the least effective amendment at increasing soil P in any of the pools studied. It is possible that a modified sequential fractionation procedure needs to be developed to improve understanding of the effects of biochar on the soil P pools.