The Effects of Soil Solarization and Mei Chemigation On Bio-Chemical Properties and Nematode Survival.

Soil fumigants have been widely used to control weeds, plant-parasitic nematodes, soil-borne fungi, and other disease organisms in high value agricultural production systems. However, fumigants are known to have a broad biocidal activity. The concern of non-target effects of soil fumigants has led investigators to study non-chemical and/or reduced-chemical pest control methods. Soil solarization, one of the organic farming practices, is environmantially safe and cost-saving. A field experiment was conducted to determine the impacts of soil solarization, methyl iodide (MeI) chemigation and their combination on soil bio-chemical properties and nematode survival. Changes in microbial biomass C, total dissolved C, NH₄-N, NO₃-N, and total dissolved N were determined at day 0, 14, 28, 84. The efficacies on pest control were determined by using bioassay muslin bags containing soil infested with citrus nematodes (Tylenchulus semipenetrans). Reduced rate (70%) of MeI chemigation reduced soil microbial biomass and increased dissolved C and N from mineralization of killed soil microorganisms while soil solarization slightly impacted these properties. Soil solarization only controlled nematodes in top 20 cm soils while MeI could eliminate nematodes in the deeper soil. The side effects of MeI on soil bio-chemical properties may be a concern for long-term soil health.