Traditional and new soil amendments reduce survival and reproduction of potato cyst nematodes, except for biochar.

Potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida , are major constraints to potato crop production. We studied the effects of several soil amendments on PCN survival and reproduction in pot experiments. Pig slurry, cattle slurry, mineral nitrogen fertilizer (NH 4 NO 3 ), crab shell compost and wood chip compost at 170 kg N ha −1 reduced the number of viable eggs in cysts of both PCN species in the absence of potato. This resulted in fewer second-stage juveniles (J2) hatching from these cysts and penetrating potato roots than from cysts of non-amended soils. When potato was planted, the same amendments resulted in less reproduction than in non-amended soil. Most reduction of reproduction was achieved in soils amended with pig slurry (87%) and wood chip compost (82%). Adding biochar at 0.3 and 1% did not reduce the survival or the reproduction of any of PCN species; moreover, it inhibited the suppressing effect of wood chip compost and pig slurry on PCN reproduction when added together with these amendments. The release of ammonium and changes in soil microbial community, determined by phospholipid fatty acid (PLFA) analysis, are involved in nematode suppression in soil amended with pig and cattle slurries. However, the suppressing effect of wood chip and crab shell compost can only be explained by the changes in soil microbiota, while the effect of mineral nitrogen fertilizer can only be related with the production of ammonium. Ammonium and microorganisms most probably have affected PCN directly by killing the eggs and juveniles or indirectly by changing the physiology of the root as mentioned amendments reduced hatch and movement of J2, penetration of the roots and females’ fecundity. [ABSTRACT FROM AUTHOR]