Epsilon Archive for Student Projects

Abstract

A holistic study on soil-borne pathogen management with suppressive soils was performed in Scania, Sweden. The study was designed to comprise both social and biological research to gain a systemic perspective on the real-life situation of Swedish farmers regarding plant pathogens and soil management. The social research comprised semi-structured interviews with a small number of farmers and an online survey, which could not be sent to farmers and therefore was without results. Possible reasons for the failure are discussed. For the biological research, soils from ten Swedish farms with different cropping and management regimes were assessed for effects on Pythium ultimum disease symptoms in wheat, physical and chemical soil parameters, and the soil nematode trophic community as identified at the family level.

Soil effects on Pythium ultimum disease symptoms were assessed in two categories: (1) biological or non-biological effects and (2) suppressive or conducive effects. Different soils had both conducive and suppressive effects, which were due to either the soil biotic community or chemical or physical properties of the soil. Management regimes with permanent plant cover had biological effects and management regimes with interrupted plant cover had non-biological effects. The nutrient balance was related to biological suppressiveness. Biologically conducive soils had either high or low nutrient content, while biologically suppressive soils had intermediate nutrient levels.

The total number of nematodes and the abundance of predators and omnivores were not related to the soil organic matter content. The abundance of hyphal-feeding nematodes was correlated with soil organic matter content. No relationship was found between the soil nematode trophic community, the soil management, and soil effects on Pythium ultimum disease symptoms. Therefore, nematode trophic guilds do not indicate soil effects on Pythium ultimum disease symptoms.