Figure 1: Environmental variables that regulate soil NOx emission.
Relationship between soil surface NOx flux (ng N m−2 s−1) and (a) days since fertilization, (b) soil volumetric water content (0–10 cm) and (c) soil temperature (average 2 and 10 cm; °C). Measurements were collected across two growing seasons 2012–2013, including measurements made during fertilization experiments (n=241). Data were binned by environmental variable and s.e. bars are shown for each bin. A Gaussian equation (f(x)=a+b*exp(−0.5((x−c)/d)2)) was fitted to the NOx relationship with days since fertilization data (a=18.6, b=254.3, c=8.6 and d=3.4). A third-order polynomial (f(x)=a*x3+b*x2+c*x+d) was fitted to the NOx relationship with soil volumetric water content (a=−8128.3, b=4125.5, c=−333.3 and d=37.4) and soil temperature (a=−0.026, b=2.4, c=−64.6 and d=562.5).
