Compost and poultry manure as preplant soil amendments for red raspberry: Comparative effects on root lesion nematodes, soil quality and risk of nitrate leaching
Citation
Forge, T., Kenney, E., Hashimoto, N., Neilsen, D., Zebarth, B. (2016). Compost and poultry manure as preplant soil amendments for red raspberry: Comparative effects on root lesion nematodes, soil quality and risk of nitrate leaching. Agriculture, Ecosystems and Environment, [online] 223 48-58. http://dx.doi.org/10.1016/j.agee.2016.02.024
Plain language summary
Raspberry fields in the Pacific Northwest, USA and British Columbia, Canada are often prepared for replanting by fumigating with broad-spectrum biocides to control soil-borne plant pathogens, primarily lesion nematodes. The addition to soil of certain organic amendments, such as poultry manure or compost made from poultry manure, can also suppress soil-borne plant pathogens and improve soil quality and raspberry growth. However, the use of such organic amendments may pose other risks to the environment such as leaching of excess nitrogen as nitrate to groundwater. This study compared poultry manure and compost amendments to fumigation with respect to effects on lesion nematode populations, soil chemical and physical properties, nitrate accumulation, and growth of young raspberry plants. Poultry manure and compost treatments both reduced lesion nematode populations and improved soil porosity nearly as well as fumigation. Raspberry plants growing in the manure and compost treated soil were larger than those growing in untreated soil, but still smaller than those growing in fumigated soil. The compost and manure treatments differed from each other in that the compost beneficially increased pH and nutrient retention capacity of the soil more than manure, and substantial amounts of nitrate accumulated in soil treated with the manure, indicating a high risk of nitrate leaching in manure-treated soil. Overall, compost application appeared to be the most environmentally friendly alternative to fumigation for reducing lesion nematode populations and improving soil health and raspberry plant growth without posing a high risk of nitrate leaching.
Abstract
Raspberry fields in the Pacific Northwest, USA and British Columbia, Canada are often prepared for replanting by fumigating with broad-spectrum biocides to control root-lesion nematodes, Pratylenchus penetrans. Nematode-suppressive organic amendments have been advocated as reduced risk alternatives to fumigation but may pose other risks to the environment. This study compared alternative pre-plant soil management practices with respect to their effects on plant-parasitic nematode populations, soil quality parameters and risk of nitrate leaching. In fall of 2009 and 2010, a mature raspberry field was mowed down and plowed, and replicate plots were randomly allocated to each of six treatments: (1) a non-amended control, (2) fumigation with Basamid®, (3) fall seeded barley cover crop, (4) recommended rate (20 m3 ha-1) and (5) historical "biofumigant" high rate (250 m3 ha-1) of spring incorporated poultry manure, and (6) spring incorporated compost (250 m3 ha-1). Raspberry cv Saanich was planted approximately one month after incorporation of amendments. Composite soil samples were taken from each plot at multiple times during 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 as an index of crop vigor. The high poultry manure and compost treatments suppressed root-lesion nematode populations nearly as well as fumigation over two growing seasons. These treatments also improved soil bulk densities and aggregation relative to control, cover crop and fumigation treatments, while compost addition beneficially increased soil pH, CEC and Ca concentrations more than manure. Primocane production in the manure and compost treatments was greater than in the control and cover crop treatments, but less than in the fumigated treatment. Substantial nitrate accumulation in soil amended with the high rate of manure indicated that application of sufficient manure to suppress parasitic nematodes would pose a significant risk of nitrate leaching. In contrast, soil nitrate accumulation was not significantly increased in the compost amended plots. Overall, compost application reduced nematode populations, improved crop growth and did not increase the risk of nitrate leaching in the short term and may be a viable alternative to fumigation.