Nitrogen leaching losses following biogas slurry irrigation to purple soil of the Three Gorges Reservoir Area

Abstract

Ammonium (NH₄⁺) in biogas slurries is readily nitrified into very mobile soil nitrate (NO₃⁻) to promote nitrogen (N) leaching concerning which a few studies, however, have been reported. These slurries are regularly applied through irrigation to purple soil in the Three Gorges Reservoir Area, and therefore we explored the consequent N leaching there with a plot experiment. Biogas slurry irrigation was carried out with nitrogen application rates of 0, 48, 144, 240, 336, and 480 kg N/ha. As a result, the last two rates have triggered N leaching being detrimental to groundwater safety. In addition, N leaching was negatively correlated with soil microbial biomass, diversity, and respiration, indicating a potential technique to prevent it with soil heterotrophs activated by increased ratios of carbon to nitrogen (C/N) in biogas slurries.