COS 89-6
Using vegetation to reduce nitrogen runoff in California caneberries
With a 700% rise in global fertilizer use in the last 50 years, agricultural lands are today the greatest source of nitrogen and phosphorus pollution in aquatic ecosystems worldwide. Record high levels of nitrate-contaminated runoff from agricultural sources in California’s Central Coast are affecting drinking water supplies in the Pajaro Valley and increasingly threatening the ecological health of the Monterey Bay. Bands of vegetation strategically planted to control runoff and soil erosion, or vegetative filter strips (VFS), are used in urban landscapes and at some farm peripheries, and on-farm vegetative diversity has been promoted for its contribution to biodiversity and pest control. The efficacy of in-row VFS for nutrient removal, however, has never before been explored in the fastest-growing agricultural commodity in Central California: caneberries. This on-farm study experimentally tested the ability of three different types of common and native VFS planted between the rows to reduce nitrogen runoff in California caneberry fields: California field sedge (Carex praegracilis), creeping wild rye (Leymus tritioides), and wild mustard (Brassica juncea).
Results/Conclusions
Nitrates in runoff decreased significantly with greater vegetation cover in vegetative filter strips (VFS). Of the three species tested, B. juncea grew fastest, but L. triticoides yielded the greatest cover by the end of the rainy season. Costs for planting and managing VFS ranged from approximately $7 per caneberry row (20 ft. x 5 ft. in-field VFS) for broadcast seed to $40 per caneberry row for plugs. VFS were shown to be a cost-effective tool that growers can use in California caneberries to decrease nitrate runoff while inherently promoting on-farm biodiversity. VFS were shown to be a cost-effective tool that growers can use in California caneberries to decrease nitrate runoff while inherently promoting on-farm biodiversity.