Yield and Economics of Organic and Conventional Tomatoes Grown in Soils Amended with Poultry Litter and Other Nutrients

Environmental concerns about the runoff of phosphorus and nitrogen from poultry waste in estuaries have prompted strict regulations against leaving surface applied manure on soil, and have established acceptable levels within which they must be applied in Maryland.  Thus, it is necessary to find suitable combinations of nutrients and acceptable levels of poultry litter (PL) to use in growing both organic and conventionally grown crops. A 2014 field study was conducted under organic and conventional systems to assess the effect of poultry litter on the yield and economics of heirloom tomatoes (Lycopersicon esculentum), Brandywine red and Debarao plum, when surface applied and then disked in the soil.  Four nutrient treatments were tested in the organic system, 1.5 tons /acre PL, 1.0 tons /acre PL plus Naturesafe 13-0-0, Naturesafe 13-0-0, and Phyta-Grow Big Red 13-0-0; and three levels at the conventional site, 1.5 tons /acre PL, 1.0 tons/acre PL plus 20-0-12 and 20-0-12 alone. For both systems, Debarao plum had higher marketable yield than Brandywine red. There were no significant effects of treatments on yield of Brandywine red in either system. Debarao plum had the highest marketable yield from the 1.5 tons/acre PL treatment in the organic system. Economic analysis based on cost-benefit ratio and profitability index for the two cultivars and different nutrient treatments, showed that growing organic Debarao plum tomatoes was the most profitable one with a profitability index greater than 4.0 at the 1.5 tons /acre PL.  The overall results for this first year’s performance indicate that growing Debarao plum heirloom tomatoes organically can be more profitable than growing them conventionally from a business perspective.