Effects of fertilizers and soil amendments on the degradation rate of allyl isothiocyanate in two typical soils of China

Abstract

Background: Allyl isothiocyanate (AITC) is a soil fumigant that protects plants against soil-borne pathogens, weeds and insects when present in the root-zone. However, the degradation of AITC under different fertilizers and soil amendments affects its emission and pest control efficacy. Degradation rates of AITC in soil amended with organic and inorganic fertilizers, zeolite and biochar were determined in the laboratory to improve its field applications.Results: The degradation half-lives of AITC were 24.4 and 35.4 h in Fangshan and Yongzhou soils, respectively, without any added fertilizer or soil amendment. Nitrogen fertilizer and organic fertilizer accelerated the degradation rate of AITC, while phosphorus fertilizer had the opposite effect. The degradation rate of AITC on adding unsterilized chicken manure was over 3.5 and 1.1 times higher than that of sterilization in Fangshan and Yongzhou soil. Inorganic and organic fertilizers affected the degradation of AITC by affecting soil microbial activity on the basis of CO 2 cumulative release. The degradation rate of AITC increased more than 0.4 times in response to zeolite, but this was independent of particle size. The AITC degradation rate increased 1.0-2.6 and 0.3-9.7 times in response to biochar made from corn stalk and pine wood, respectively. Cow manure biochar manufactured at different pyrolyzation temperatures had different effects on the degradation rate of AITC. Conclusion: Soil type, fertilizers and soil amendments differentially affect the degradation rate of AITC by changing soil physicochemical characteristics, microorganisms, etc., which shows great potential in reducing AITC emissions and increasing pest control efficacy when AITC is applied commercially.

Encapsulated allyl isothiocyanate improves soil distribution, efficacy against soil‐borne pathogens and tomato yield

“…The emulsifiable concentrate in water (EW) formulation was first registered in China as a nematicide in 2018 applied by drip irrigation. 4 AITC, like many other plant-derived products, is reported to have a low environmental impact. 4 The efficacy of a fumigant against pathogens depends on fumigant concentrations in soil remaining lethal to pathogens for sufficient time.…”

“…4 AITC, like many other plant-derived products, is reported to have a low environmental impact. 4 The efficacy of a fumigant against pathogens depends on fumigant concentrations in soil remaining lethal to pathogens for sufficient time. 5 The physicochemical properties of fumigants govern their distribution through and persistence in the soil.…”

“…8,9 Zhang et al reported that AITC was evenly distributed within 10 cm of the surface and the concentration decreased as water content increased; drip irrigation improved AITC's distribution and its efficacy against soil-borne pathogens. 4 However, applying AITC by drip irrigation may not be a viable option in areas where water is scarce or expensive. 10,11 The emission behavior of fumigants and their efficacy against pathogens can be improved by processing them into granules.…”

Comparison of drip‐irrigated or injected allyl isothiocyanate against key soil‐borne pathogens and weeds

“…In China, AITC is registered as a nematicide in 2018; the recommended application method is drip irrigation at 0.9–1.5 g a.i. m −2 to soil before planting 7 …”

“…m −2 to soil before planting. 7 To be efficacious, soil fumigants must maintain a concentration lethal to pests in the soil for a minimum period of time. [8][9][10] The distribution of fumigants in the soil and their efficacy against pests is determined by the fumigant's physical and chemical properties, how they are applied to soil, and environmental factors such as soil moisture content and temperature.…”