Updating Nitrogen Fertility Recommendations for Mid-Atlantic Vegetable Crops

Commercial nitrogen (N) recommendations for Virginia-grown fresh market tomatoes (Solanum lycopersicum) and pumpkin (Cucurbita pep var. pepo) need revision to provide more accurate recommendations for current agricultural production systems. For tomato, two N application methods (banded and incorporated) x five N rates (0, 100, 200, 300, and 400 lb/acre N) were applied to polyethylene mulched fresh market tomatoes grown on a sandy loam soil during three growing seasons. For all treatments, 50% of total applied N was applied pre-plant and 50% via fertigation. Pre-plant N was 100% incorporated or 33% incorporated and 67% banded for the incorporated and banded treatments, respectively. Then, plots were fumigated and polyethylene mulch was laid. Nitrogen rates for maximum yield ranged from 164-195 lb/acre N for the incorporated method and 178-215 lb/acre N for the banded method. The banded method produced greater yields in 2 seasons, and unlike the incorporated method, did not experience crop loss in a hot, dry season. For pumpkin, we applied 20, 40, 80, and 120 lb/acre N in a split application between at-planting and sidedress when plants begin to run on a sandy loam and silt loam soil. All pumpkin plots were planted following high-residue rye cover crops. Optimal yield ranged from 0-120 lb/acre N across the three-year study. Overall, Virginia commercial N fertilizer recommendations for fresh market tomato should be updated to 178-215 lb/acre N using the banded method for optimum yields and to prevent crop loss in unseasonable years. Pumpkin N rates may also need to be increased and should be based on in-season tissue tests and yearly seasonal variations as necessary N rates ranged widely.