Fig. 1.
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.
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.
Fig. 3.

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

 


Fig. 4.
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.
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.
Fig. 6.

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