Optimizing Application of Phosphorus and Potassium to Processing Tomatoes under Drip Irrigation

IPNI-2007-CAN-ON28

18 May 2007

Project Description

Optimizing Application of Phosphorus and Potassium to Processing Tomatoes under Drip Irrigation to Minimize Adverse Impacts on Water Quality While Maximizing Quality and Yield



Processing tomatoes, a major high-value crop in Ontario, are high in nutrient demand. The nutrient needs can further increase with drip irrigation/fertigation, a local common practice, due to enhanced yield potential. Our studies in the past 5 years show that the fertilizer N rate required for processing tomato production with drip fertigation should be 270 kg N/ha. With increased need for fertilizer N, other nutrients, such as phosphorus (P) and potassium (K), must be supplied accordingly in sufficient amounts. Application of fertilizer P and K for processing tomatoes must be optimized in a way that minimizes adverse effect on water quality, while maintaining product quality and maximum marketable yield. However, data on P and K is not available for processing tomatoes with drip irrigation, and have to be developed for Ontario conditions. Quality of processing tomatoes has become an emerging issue from both processors and consumers. These qualities include soluble solids, lycopene, and vitamin C. However, information on the roles of P and K in the formation of these food quality variables are limited and often in controversy. The industry organizations (Ontario Tomato Research Institute, International Plant Nutrition Institute, A&L Canada Laboratories Inc., and The Fertilizer Institute Of Ontario Foundation, Inc.) have jointly agreed to support this research on optimization of P and K application for processing tomatoes in an environmentally responsible manner to maximize yield and quality as top research priority. The project is intended to continue for three years starting in 2007.

Objectives:
    1. To evaluate the potential leaching losses of soil P and N.
    2. To determine crop nutrient (N, P, K) uptake and removals.
    3. To determine the relationships between fertilizer P and K and quality of processing tomatoes under drip irrigation in according with the newly developed N rate in Ontario.
    4. To develop the optimum rates of P and K under Ontario conditions, that minimizes potential for P losses, while meeting the needs for maximum quality and economic yield.