Abstract: | Populations of Pratylenchus penetrans decreased in soil following addition of 70 and 700 ppm N in the form of nitrate, nitrite, organic nitrogen, or ammonium compounds. Nitrate was less effective than other nitrogen carriers. Population reduction is principally attributed to ammonification during decomposition. This hypothesis is supported by chromatographic analyses of soil atmospheres, survival of nematodes in pure CO₂ and N₂, inverse relationship of CO₂, content in amended soils to nematode populations, and direct relationship of NH₃-N content of amended soils to nematode populations. |