Relationships between nematode diversity, plant biomass, nutrient cycling and soil suppressiveness in fumigated soils

• Nematode diversity was very affected by soil fumigation.
• Untreated furrows were a reservoir of beneficial and parasitic nematodes.
• Nematodes were more closely associated to nutrient cycling in non-cropped than in cropped soils.
• Plant biomass was weakly linked to soil food web condition.
• Treated soils were less suppressive than unmanaged soils.

Nematodes interact with many other organisms as participants in several links of the soil food web, playing important roles in essential soil processes. Due to their high abundance and diversity of responses to soil disturbance, nematodes are suitable indicators of soil condition. With the aim of inferring soil fumigation effects on agroecosystem functioning, soil nematode diversity, soil properties, plant growth, and soil suppressiveness were monitored in a commercial strawberry farm and its surroundings for two consecutive growing seasons in southern Spain. Our results show that nematode diversity was low in fumigated soils throughout the whole season and, although yearly recovery occurred within the treated fields, fumigated soils showed a permanent perturbed condition. The nematode community was more closely associated to nutrient cycling in non-cropped than in cropped soils, and the link between plant biomass and nematode community structure was weak. Non-treated furrows within the treated fields were a reservoir of both beneficial and plant-parasitic nematodes, but such difference between furrows and beds was not enough to maintain more suppressive soil assemblages in the furrows. Treated soils were less suppressive than unmanaged soils, and there was a positive and significant correlation between soil suppressiveness and soil food web structure and diversity.