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Improving nitrogen retention of cattle slurry with oxidized biochar: An incubation study with three different soils (2023)

Cao X., Reichel R., Wissel H., Brüggemann N.

Journal of Environmental Quality, 52 (1), 1-12



The application of livestock slurry in soils can lead to nitrogen (N) losses through ammonia (NH3) emission or nitrate (NO3) leaching. Oxidized biochar has great potential to mitigate N losses due to its strong adsorption capacity; however, the effects of oxidized biochar in different soils treated with slurry are currently unclear. Here, we investigated the effect of untreated and oxidized biochar (applied at a rate of 50 kg C m−3 slurry) on reducing N losses in a laboratory experiment with three different soils (loamy sand, sandy loam, loam) amended with cattle slurry at an application rate of 73 kg N ha−1. Oxidized biochar reduced NH3 emissions by 64–75% in all soils, whereas untreated biochar reduced NH3 emissions by 61% only in the loamy sand. Oxidized biochar significantly reduced the NO3 content in the soil solution of the loamy sand in the early phase of the incubation and led to a significantly higher NO3 concentration in the same soil compared with the slurry-only treatment at the end of the experiment, indicating a significant increase in NO3 retention in this organic C–poor soil. We conclude that oxidized biochar can reduce N losses, both in the form of NH3 emission and NO3 leaching, from cattle slurry applied to soil, particularly in soil with soil organic carbon content <1% and pH <5 (i.e., oxidized biochar can serve as a means for improving the quality of marginal and acidic soils).