Agricultural waste amendments improve inundation treatment of soil contaminated with potato cyst nematodes, Globodera rostochiensis and G. pallida

Abstract

Potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida, are major constraints to potato production. They are distributed passively with soil adhering to farm machinery and harvested tubers, but also by waste soil from trading and processing plants. Inundation is considered an environmentally save method for disinfestation of waste soil. We investigated if agro-industrial waste products accelerate this disinfestation process by studying PCN survival, hatching and infectivity over time. Experiments were conducted in 2-L containers filled with 1.5 L non-amended soil, soil amended with steamed or fresh potato peels, calcium sulphate, steamed potato peels mixed with calcium sulphate, or leek leaves. In each container, cysts of G. rostochiensis or G. pallida were buried in the soil in retrievable bags and 400 ml water was added. Non-amended and non-inundated soils were the controls. It took 8 weeks of inundation of non-amended soil to reduce nematode survival by 72 %, while in amended soils survival was reduced up to 99.9 % after 4 weeks. After 1 week, fewer second-stage juveniles (J2) hatched and infected roots in inundated amended soil than in inundated non-amended soil. Host finding ability of surviving J2 was not affected. To understand mechanisms of nematode suppression, concentrations of short chain fatty acids (SCFA), gases (O2, CO2, H2S, CH4, and N2) and phospholipid fatty acids (PLFAs) were determined. Higher concentrations of SCFA and carbon dioxide and lower levels of oxygen were detected in amended treatments. H2S was occasionally detected in the leek-amended soil. The microbial biomass changed significantly in potato peels-amended soils.