Arise Research is one of the few facilities which can accurately measure nitrate runoff. Each plot is grown in a containment bay where there is a plastic lining on the bottom and sides. There is also a piping system in the containment bay to collect the runoff which goes into a holding tank (58 in the photo below). The water is collected from the holding tank where it can analyzed.
An interesting tidbit was reported in an email that there had been deer damage to the SumaGrown test plots where the deer were observed eating the SumaGrown plots and not the others. This has been reported anecdotally several times; the animals instinctively know which crops are better (SumaGrown), likely due to the higher brix levels — better taste (higher in natural sugars) and higher nutritional value.
Here is a link to the summary of the report and below that is the full report from Arise Research: