Soil sterilization and organic carbon, but not microbial inoculants, change microbial communities in replanted peach orchards
California Agriculture 59(3):176-181. DOI: 10.3733/ca.v059n03p176.
Methyl bromide is highly effective in reducing soil pathogens. Although its use was to be phased out completely in the United States by Jan. 1, 2005, due to environmental concerns, a 1-year critical-use exemption will allow tree fruit growers to use the fumigant through the end of the year. To explore possible replacements for methyl bromide, we compared the effects of pre- and postplant treatments and amendments on soil microbial communities and tree vigor in a replanted peach orchard. Both soil sterilization treatments and organic carbon amendments changed the composition of microbial communities in the soil. High microbial biomass is generally considered beneficial to agricultural soils; we found that it was usually highest in soils that received the organic carbon amendment and lowest in those with soil sterilization. However, tree vigor was highest with the sterilization treatments. The effects of a microbial inoculants/organic carbon combination on microbial communities and plant vigor were no different from simply adding organic carbon.
R.E. Drenovsky is Postdoctoral Researcher; R.A. Duncan is Farm Advisor, UC Cooperative Extension, Stanislaus County. The authors thank Kevin Feris for manuscript review, and Kim Chuong, Levina Loveless, Anita Setty and Angela Maroney for sample preparation and analysis. A special thank you is extended to Norman Kline, grower, for participating in the trial. A grant from the California Cling Peach Board made this work possible. K.M. Scow is Professor, Department of Land, Air and Water Resources, UC Davis;