Fig. 2
From: Real-time monitoring of rhizosphere nitrate fluctuations under crops following defoliation
NO3−-selective sensors readings correlated with conventional soil water NO3− extraction analysis assay results collected using a mini-suction lysimeter (see Materials and Methods for details). The same soil sample was treated with a range of nitrate concentrations each in four different pots and then measured for NO3−–N as ppm using both NO3−-selective sensors and suction lysimeter water samples assayed using a conventional Griess assay. NO3−–N ppm are the units most used by soil scientists; the sensors were calibrated to give outputs in mM too. The graph shows strong agreement between measurements (R2 = 0.99)