Effect of a nitrification inhibitor on nematicidal activity of organic and inorganic ammonia-releasing compounds against the root-knot nematode Meloidogyne javanica

摘要

The nematicidal activities of ammonium hydroxide, chitin and cottonseed meal applied to soil were enhanced by nitrapyrin, a nitrification inhibitor, in pot experiments. In a field trial, root galling index of tomato plants grown in the soil treated with 250 kg NH4OH-N/ha in combination with nitrapyrin was lower than that of tomato plants grown without nitrapyrin 40 days after planting; however, there was no difference between these treatments in tomato yields and root galling indices at the end of the experiment (128 days). Nitrapyrin inhibited the nitrification of the ammonium added to the soil or released from cottonseed meal for up to 28 days, and kept ammonium concentrations and soil pH values higher for longer periods compared with those in soils treated without nitrapyrin. It is suggested that higher ammonia (NH3) concentrations due to high soil pH and ammonium concentrations in the soil for longer periods caused the enhancement of nematicidal activities by nitrapyrin. The use of ammonia-releasing compounds in combination with a nitrification inhibitor may make nematode control more feasible by reducing the amount of amendments applied.