Plant uptake of nitrogen adsorbed to biochars made from dairy manure

Abstract

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 (NH3) in the liquid fraction using pyrolysis and pre-treatment with carbon dioxide (CO2). The extractable N in manure biochar exposed to NH3 following CO2 pre-treatment reached 3.36 g N kg−1, 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 CO2 + NH3 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 CO2 + NH3, compared to N-equivalent treatments. The available N in dairy waste in New York (NY) state, if pyrolyzed and treated with NH3 + CO2, is equivalent to 11,732–42,232 Mg N year−1, valued at 6–21.5 million USD year−1. Separated dairy manure treated with CO2 + NH3 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.

Methane and nitrous oxide emissions during biochar‐composting are driven by biochar application rate and aggregate formation

“…Chemisorbed $$$ {\mathrm{NH}}_4^{+} $$$ would be retained on the biochar surface and would explain why there was no difference in KCl‐extractable $$$ {\mathrm{NH}}_4^{+} $$$ between biochar treatments and the control. Chemisorption has recently been shown to be an important and previously overlooked mechanism through which biochar can retain $$$ {\mathrm{NH}}_4^{+} $$$ (Hestrin et al., 2019; Krounbi et al., 2020, 2021).…”

Biochar integrated reactive filtration of wastewater for P removal and recovery, micropollutant catalytic oxidation, and negative CO2e: Process operation and mechanism

“…For the total carbon, nitrogen, and sulfur (CNS) composition, the native and recovered biochar were analyzed using Elementar Vario Max Cube (Elementar Americas Inc., Ronkonkoma, NY, USA) as outlined in Bird, Keitel, and Meredith (Bird et al, 2017). Two samples were run in duplicate, with relative standard deviation being 1%–2% for C and N. For inorganic N composition (i.e., NO 3 /NO 2 and NH 4 ), the native and recovered biochar were analyzed using the method prescribed by Krounbi et al (2021) and Mulvaney (1996). Plant‐available P in the native and Fe‐BC‐RF P upcycled biochar was determined using a 2% formic acid extraction method described by Wang et al (2012).…”

Biochar-composting substantially reduces methane and air pollutant emissions from dairy manure

“…Under high NH 3 concentrations, chemisorption might happen relatively quickly. Previous studies have found that chemisorption of NH 3 by biochar can happen rapidly (over several hours), even at near-ambient conditions [85,87]. While chemisorbed NH 3 -N on biochar may slowly become plant available, other properties of biocharcompost, such as the formation of a mixed-charge organo-mineral layer on the composted biochar surface, may prove to be more important for helping to retain and later deliver nutrients to plants [21,88].…”