Effect of soil storage duration and two nematode extraction methods on nematode recovery from a Florida sandy soil

Summary Soil nematodes, both free-living and plant-parasitic, are key bioindicators of soil health and integral players in agroecosystem functioning. Accurate quantification of these nematodes is critical for understanding soil ecology and implementing effective nematode management. However, nematode recovery is influenced by factors such as extraction method, and storage duration. In August 2023 and February 2024, soil was collected in a zigzag pattern from 12 experimental vegetable field plots at the University of Florida Gulf Coast Research and Education Center and stored at 5°C. Two extraction methods were used: i ) an active method, the modified Baermann pan technique by using a salad spinner bowl and basket (SS); and ii ) a passive method, the sugar flotation technique by using a centrifuge (SF). Nematodes were extracted at 0, 14, 30, 60 and 90 days after storage (DAS). The results showed that both extraction method and storage duration significantly affected nematode recovery. SF recovered significantly higher plant-parasitic nematodes than SS, whilst SS was optimal for free-living nematodes when processed immediately (DAS = 0). SF was more effective for free-living nematodes at DAS = 90 and for plant-parasitic nematodes at DAS = 43.5. Survival analyses confirmed these trends with estimated decline rates (DR) DR SF = −0.0005 and DR SS = 0.012 for free-living nematodes and DR SF = 0.01 and DR SS = 0.025 for plant-parasitic nematodes. These findings indicated that immediate processing is ideal, particularly with SS technique used, but when storage is required, SF offers better nematode recovery over extended durations.