Strawberries are a high-value crop but there are a number of sustainability concerns with conventional production practices, namely the use of methyl bromide fumigation. Poor soil fertility and high pest pressures in the Southeastern United States (SE US), coupled with production practices where strawberries are often replanted year after year in the same location, has led to greater challenges for producers to phase out of methyl bromide use. Moreover, these practices have depleted soil nutrient levels, increasing reliance on well-timed synthetic fertilizer applications. With federal restrictions on methyl bromide increasing and full phase-out near, many producers are considering different synthetic alternatives, but environmental and health risks may be significant. There is a critical need for sustainable alternatives to methyl bromide use for both conventional and organic strawberry production in the SE US that enhance overall soil health. Alternatives should focus on system level approaches promoting healthy, productive plants and enhancing beneficial microbial populations, while reducing pest pressures over the long term.
The primary objective of this study was to examine the integrated effects of composts with six summer cover crop treatments and two beneficial soil inoculants on strawberry growth, yields, weed pressure, arbuscular mycorrhizal fungi (AMF) colonization, and soil N levels in a 2-year field experiment. Compost and cover crop treatments consisted of 1) Pearl millet, (Pennisetum glaucum); 2) Soybean, (Glycine max), 3) Cowpea, (Vigna unguiculata); 4) Pearl millet/Soybean and 5) Pearl millet/Cowpea, and 6) a no cover crop control treatment without compost. Beneficial soil inoculant treatments consisted of the background native AMF present in the field and AMF with vermicompost added at the time of planting.
Results/Conclusions
The use of beneficial soil inoculants when combined together (AMF + Vermicompost) improved strawberry biomass, yield, and soil N, but not AMF colonization both years. Weed suppression by cover crops in the summer did not carry over into the strawberry season, where weed abundance was lowest in control plots. The amount of increased N supplied through compost and cover crops during critical strawberry growth stages appears to equalize the effect of adding supplemental fertilizers in organic production systems. Results from our research suggest that recommended fertilizer application rates for the SE strawberry production might exceed the nitrogen requirements for strawberries when using cover crops and organic amendments.