ASA Section: Environmental Quality [Oral]

Effects of biochar amendment on ammonia volatilization from soil under ruminant urine application and its subsequent plant availability

Arezoo Taghizadeh-Toosi¹, Tim J. Clough¹, Robert R. Sherlock¹, and Leo M. Condron^1&2

¹Dep. of Soil & Physical Sciences, Faculty of Agriculture & Life Sciences, P.O. Box 84, Lincoln Univ., Lincoln 7647, New Zealand; Arezoo.Taghizadehtoosi@lincolnuni.ac.nz, Timothy.Clough@lincoln.ac.nz, Rob.Sherlock@lincoln.ac.nz.

²Bio-Protection Research Centre, P.O. Box 84, Lincoln Univ., Lincoln 7647, New Zealand; Leo.Condron@lincoln.ac.nz.

Abstract

Ammonia (NH₃) can be generated at the soil surface following the surface application of nitrogenous fertilizers or ruminant urine deposition and can vary widely from 1.7% to 56% of the applied nitrogen (N). The volatilization of NH₃ represents the loss of a potentially available agronomic N supply and an environmental source of reactive N, since NH₃-N may contribute to indirect losses of nitrous oxide, a GHG. This study was conducted in two steps in order to determine the effect of incorporating biochar (0, 15 and 30 t ha^-1), into soil on (a) NH₃ volatilization under a ruminant urine application, and (b) the subsequent plant availability of biochar adsorbed NH₃-N. The NH₃ volatilization from ¹⁵N-labelled ruminant urine, applied to soil, was reduced by 45% after incorporating either 15 or 30 t ha^-1 of biochar. The atom
% ¹⁵N enrichment of the NH₃ volatilized was lower with biochar present, indicating less urine-N contributed to the NH₃ flux. Furthermore, the biochar total N content and its ¹⁵N enrichment increased. When these ¹⁵N enriched biochar particles were placed in fresh soil, subsequent plant growth was not affected but the uptake of ¹⁵N in plant tissues increased, indicating that the adsorbed-N was plant available.

Incorporating biochar into the soil can significantly decrease NH₃ volatilization from ruminant urine. However, future work is required to examine the persistence of the observed effect under field conditions, and to fully understand the mechanism(s) of the observed reduction in NH₃ fluxes.