Changes of tomato yield and fruit elemental composition in conventional, low input, and organic systems

The Sustainable Agriculture Farming System (SAFS) Project was begun in 1988 to compare conventional 4-year and 2-year rotations receiving synthetic fertilizers and pesticides to low input and organic farming systems. In 1998 and 1999, we evaluated the influence of 10 years of organic, low input, and conventional management practices on soil chemical properties, processing tomato yields, and fruit mineral composition. The organic system had highest soil total C, N, soluble P, exchangeable Ca, and K levels as a result of 10 years of manure application and cover crop use. In both years, fruit yields were similar in the three farming systems. Organic fruits contained highest amounts of P, and Ca. Conventionally-grown tomatoes were richer in N, and Na, while the low input system had an intermediate values for N, P, and Na, and the lowest Ca concentration of the three systems.