title: Cross-site soil microbial communities under tillage regimes: fungistasis and microbial biomarkers.
abstract: The exploitation of soil ecosystem services by agricultural management strategies requires knowledge of microbial communities in different management regimes. Crop cover by no-till management protects the soil surface, reducing the risk of erosion and nutrient leaching, but might increase straw residue-borne and soilborne plant-pathogenic fungi. A cross-site study of soil microbial communities and Fusarium fungistasis was conducted on six long-term agricultural fields with no-till and moldboard-plowed treatments. Microbial communities were studied at the topsoil surface (0 to 5 cm) and bottom (10 to 20 cm) by general bacterial and actinobacterial terminal restriction fragment length polymorphism (T-RFLP) and phospholipid fatty acid (PLFA) analyses. Fusarium culmorum soil fungistasis describing soil receptivity to plant-pathogenic fungi was explored by using the surface layer method. Soil depth had a significant impact on general bacterial as well as actinobacterial communities and PLFA profiles in no-till treatment, with a clear spatial distinction of communities (P < 0.05), whereas the depth-related separation of microbial communities was not observed in plowed fields. The fungal biomass was higher in no-till surface soil than in plowed soil (P < 0.07). Soil total microbial biomass and fungal biomass correlated with fungistasis (P < 0.02 for the sum of PLFAs; P < 0.001 for PLFA 18:2ω6). Our cross-site study demonstrated that agricultural management strategies can have a major impact on soil microbial community structures, indicating that it is possible to influence the soil processes with management decisions. The interactions between plant-pathogenic fungi and soil microbial communities are multifaceted, and a high level of fungistasis could be linked to the high microbial biomass in soil but not to the specific management strategy.
authors.affiliation: Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland. timo.p.sipila@helsinki.fi
authors.forename: Timo P
authors.initials: TP
authors.lastname: Sipilä
authors.forename: Kim
authors.initials: K
authors.lastname: Yrjälä
authors.forename: Laura
authors.initials: L
authors.lastname: Alakukku
authors.forename: Ansa
authors.initials: A
authors.lastname: Palojärvi
mesh_terms: D000383:Agriculture / Q000379:methods*; D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D058491:Bacterial Load; D058448:Biota; D015169:Colony Count, Microbial; D016172:DNA Fingerprinting; D005670:Fusarium / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D010743:Phospholipids / Q000032:analysis; D012150:Polymorphism, Restriction Fragment Length; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D010743:Phospholipids; D012987:Soil