A case for applying the coloniser-persister scale when quantifying effects of regenerative agricultural practices on herbivore nematodes

Summary Conservation tillage, cover crops, and nutrient amendments are among the regenerative agricultural practices applied to suppress herbivore nematodes (Hvs) and improve soil health for which beneficial nematodes (BNs) are an indicator. Since Hvs and BNs exist in the same environment, quantifying Hvs in ways that parallel BNs could lead to improved ways of managing Hvs and soil health. This study advances concepts of accounting for all Hvs regardless of population density, mode of parasitism or host range and quantifying them on the 1-5 coloniser-persister (cp) ecophysiological scale grouped as cp 2 (Hvs2), cp 3-5 (Hvs35), and the sum of all (HvSum). We tested the effects of 4-year (Y) treatment of tillage (T), winter rye ‘Wheeler’ cover crop (C) and rates 0, 112 or 224 kg ha −1 nitrogen amendment (N) from inorganic and compost sources on all Hv groups under corn production. The total abundance of the Hv genera was very low, and C and N had no effect, potentially leading to little management concern and dropping the regenerative agricultural practices. When expressed on the ecophysiological scale, however, Hvs2 were only affected by the interaction of C*Y; whereas, conventional tillage, T*Y, N*Y, T*C*N and T*C*N*Y significantly decreased Hvs35, thus showing that the regenerative agricultural practices affect Hvs2 and Hvs35 differently. The cumulative accounting of Hvs grouped as Hvs2 and Hvs35 serves as a foundation for comparing Hvs and BNs on the same ecophysiolocal scale and improves the application of regenerative agricultural practices.