Anaerobic soil disinfestation: Nutrient cycling and potential environmental impact

Anaerobic soil disinfestation (ASD) is a pre-plant biological soil disinfestation technique proposed for the simultaneous control of soilborne pathogens, nematodes, and weeds in several horticultural crops grown in conventional and organic systems. The technique is applied by amending the soil with a labile carbon source, tarping the soil with totally impermeable film, and irrigating the soil to saturation. The rapid shift of redox potential stimulates the growth of anaerobic microorganisms and the anaerobic decomposition of the C source, with the consequent production of metabolites (organic acids, aldehydes, alcohols, ammonia, and volatile organic compounds), which results in the suppression of many soilborne pathogens and pests. The changes in the soil microbial population, redox potential, and pH that occur during ASD may also have an impact on nutrient cycling, thereby affecting soil fertility, availability of nutrients for the crop, and potential loss of nutrients into the environment. Understanding the nutrient dynamics and the factors that influence the availability and/or loss of nutrients during and after ASD treatment is critical for the sustainable application of this technique on a large scale. The objective of this work was to review the factors that govern the nutrient cycling in relation to ASD treatment, discuss potential solutions to optimize crop nutrient management and minimize the risks of nutrient loss, and identify future research priorities. While there are concerns about N₂O emissions and nutrient leaching, the results of previous studies and of ongoing research activities conducted at multiple sites suggest that the risks of nutrient loss are not higher than those associated with standard chemical soil fumigation practices. Instead, there is clear evidence that ASD has both short- and long-term effects on the soil fertility and, excluding some risks of phytotoxicity at transplanting, ASD has been demonstrated to have positive effects on plant growth and crop yield.