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

IPNI-2002-CAN-ON27

28 Jan 2005

2004 Annual Interpretive Summary


Nitrogen and Phosphorus Needs for Tomatoes and Green Peppers, 2004

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 was used for intensive management.

Results of the first 2 years indicated optimum rates of N of 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.

In the 2004 growing season, optimum marketable yields required 250 lb N/A of N for green peppers, and 260 lb N/A for tomatoes. These rates exceed the current recommendations four-fold for peppers and two-fold for tomatoes. The optimum rates also exceed nutrient removals by the crops. ON-27F