In a field experiment on a farm registered for organic production, we studied the effect of the application of different organic materials (OM): farmyard manure (FYM), guano (G), soybean seed (S), forage pea seed (P) on lettuce yield. Besides yield, we also analyzed the economic profitability of the application of different OM. Fresh lettuce yield was significantly higher with OM treatments than with the treatments without fertilization. The highest yield was obtained with the FYM treatment (43.7 t ha-1), and the lowest with the application of P (42.0 t ha-1). The highest additional profit was obtained with the FYM treatment (1123 EUR ha-1) and the lowest with the application of P (475 EUR ha-1)
