The use of compost as a preplant amendment to minimize impacts of parasitic nematodes and improve soil health and early establishment of red raspberry.

Raspberry fields in the Pacific Northwest, USA and British Columbia are often prepared for replanting by fumigating with broad spectrum biocides to control root-lesion nematodes (Pratylenchus penetrans). Fumigation poses risks to the environment, however. The aim of our research was to identify alternative pre-plant soil management practices that reduce the impacts of parasitic nematodes, improve soil ecosystem health and improve raspberry establishment without having deleterious effects on the environment. In fall of 2009 and 2010, a portion of a mature raspberry field was mowed down, ploughed, disked and separated into 30 plots, and then five replicate plots were randomly allocated to each of the following treatments: (1) fumigation, (2) fall barley cover crop, (3) spring incorporation of poultry manure at (3) 20 m3 ha-1 and (4) 250 m3 ha-1, (5) incorporation of compost at 250 m3 ha-1, and (6) a non-amended control. Raspberry ‘Saanich’ was planted in the plots approximately one month after incorporation of amendments. Composite soil samples were taken from each plot at multiple times through two subsequent growing seasons and analyzed for nematode populations and soil chemical and physical properties. Primocane biomass was assessed at the end of each of the first two growing seasons. The high poultry manure and compost treatments suppressed root-lesion nematode populations nearly as well as fumigation through two growing seasons, and primocane production in those treatments was greater than in the control and cover crop treatments but less than in the fumigated treatment. Substantial amounts of nitrate accumulated in soil amended with the high rate of manure, indicating that using manure at rates sufficiently high to suppress parasitic nematodes would pose a significant risk of nitrate leaching. In contrast, accumulation of nitrate in the compost amended plots was not significantly different from the other treatments.