Fig. 1.

Field trial layout showing the position of the gas chambers and soil sampling plots within the biochar treated plots (0, 15, or 30 t ha−1).

 


Fig. 2.

Rainfall, soil and air temperatures over the 86-d experimental period at the meteorological station site 3 km from the trial site. Gravimetric water content values were determined from in situ sampling at the field site.

 


Fig. 3.

Soil surface pH over time, following urine application (error bars ± one standard error of the mean, n = 5).

 


Fig. 4.

Soil ammonium N and nitrate N concentrations over time, following urine application (error bars ± one standard error of the mean, n = 5).

 


Fig. 5.

(a) Geometric mean nitrous oxide emissions from different treatments following urine application (error bars ± one geometric standard error of the mean, n = 5); (b) Nontransformed cumulative loss of N2O from urine-treated soils, showing the amount of N emitted as N2O-N as a percent of the total N applied to the plots. Nil urine is also plotted to show control emissions. (Error bars ± one standard error of the mean, n = 5).

 


Fig. 6.

Nitrous oxide 15N atom% enrichment determined for treatments (error bars ± one standard error of the mean, n = 5).