However, other scientists from WUR identified inconsistencies in the publication regarding the approach of the research and the interpretation of the results, and decided to reanalyze the setup and results. The crops cultivated were inconsistent over the 13 years: the early years involved more sugar beets while the later years saw more maize. This made it seem like the yield of the organic crops increased on average, although this was not the case for each crop.
In a comparison between the systems in later years (2011-2016), which saw the same crops being cultivated every year, the difference between organic and conventional agriculture in Vredepeel was a constant 20%. This percentage is in line with all recent meta-analyses, which examined the difference between organic and conventional agriculture based on a large number of studies.
Further analysis showed that the soil of the organic testing fields in the research in Vredepeel had different properties than the soil of the non-organic fields (different groundwater levels and, originally, a higher soil organic matter content), which may have reduced the leaching of nitrate.
For more details, read the news article from Wageningen University & Research.