Nitrogen and Phosphorus Needs for Tomatoes and Green Peppers Grown with Drip Irrigation

Processing tomatoes and green peppers are examples of high-value food crops whose production may be impacted by the regulation of nutrient management. This experiment, initiated in 2002, aimed to determine the effects of nitrogen (N) and phosphorus (P) on yield and quality of the two crops, and on risk of nutrient losses. Drip fertigation is used for intensive management.

Results of the past 2 years show the inadequacy of current recommendations for optimum yield and quality. Optimum rates of N were found to be 180 to 190 lb/A, approximately double the current recommendations. Phosphorus fertilizer increased the marketable yield of peppers both years, despite soil test levels so high that no P would have been recommended.

Results from the 2003 season also showed the importance of balanced nutrition for protection of groundwater quality. Increasing levels of P fertilizer decreased the residual nitrate in the soil following harvest. The trial is continuing in 2004. ON-27F