Plant uptake of nitrogen adsorbed to biochars made from dairy manure

• Published in: Scientific reports Vol. 11; no. 1; pp. 15001 - 12
• Main Authors: Krounbi, Leilah, Enders, Akio, Gaunt, John, Ball, Margaret, Lehmann, Johannes
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 22.07.2021; Nature Publishing Group UK; Nature Portfolio
• Subjects: Ammonia; Ammonium; Animal wastes; Carbon dioxide; Charcoal; Crop production; Dairy wastes; Environmental degradation; Fertilizers; Manures; Moisture content; Plant growth; Pollution control; Production costs; Pyrolysis; Tomatoes
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-94337-8

The conversion of dairy waste with high moisture contents to dry fertilizers may reduce environmental degradation while lowering crop production costs. We converted the solid portion of screw-pressed dairy manure into a sorbent for volatile ammonia (NH ) in the liquid fraction using pyrolysis and pre-treatment with carbon dioxide (CO ). The extractable N in manure biochar exposed to NH following CO pre-treatment reached 3.36 g N kg , 1260-fold greater extractable N than in untreated manure biochar. Ammonia exposure was 142-times more effective in increasing extractable N than immersing manure biochar in the liquid fraction containing dissolved ammonium. Radish and tomato grown in horticultural media with manure biochar treated with CO  + NH promoted up to 35% greater plant growth (dry weight) and 36-83% greater N uptake compared to manure biochar alone. Uptake of N was similar between plants grown with wood biochar exposed to CO  + NH , compared to N-equivalent treatments. The available N in dairy waste in New York (NY) state, if pyrolyzed and treated with NH  + CO , is equivalent to 11,732-42,232 Mg N year , valued at 6-21.5 million USD year . Separated dairy manure treated with CO  + NH can offset 23-82% of N fertilizer needs of NY State, while stabilizing both the solid and liquid fraction of manure for reduced environmental pollution.