Nutrient Management Research Database

General Information

Fertigation Boosts Optimum Nitrogen for Tomatoes and Peppers

http://ucanr.edu/sites/nm/files/76648.pdf

Crop: Tomato

Soil Type: Sandy Loam

Country: Canada

Year: 2006

Zhang, T., Tan, C., & Bruulsema, T.

Fertilizing vegetable crops requires a delicate balance between yield, quality, and environmental impact.
Fertigation increases response to nitrogen (N) and provides greater opportunity to control rates to optimum levels.
This article discusses optimum rates of nitrogen fertilization for yield and quality, while minimizing environmental impact, in Ontario Canada.

The experiments on both crops included four rates of N and three rates of P in all 12 combinations.
All of the P and 40% of the N requirement was applied pre-plant.
The remaining N was supplied by fertigation.
The soils were Granby sandy loams or loamy sands, with organic carbon content of 1.7%, at the research station in Harrow, Ontario.
Soil P and K fertility was very high–generally above 60 parts per million (ppm) Olsen-P, and above 200 ppm exchangeable K.

Over three growing seasons - 2003 to 2005 - optimum marketable yields required 180-214 lb/A for green peppers and 190 to 270 lb/A for tomatoes.
These rates exceeded recommendations for the soil type by two to three fold.
N removal efficiency ranged from 50% to 80% for tomatoes fertilized at the mean optimum rate of 240 lb/A.
At that rate, N recovery efficiency ranged from 31% to 68%.
Peppers were less efficient, with N removal efficiencies between 22% and 30% and recovery efficiencies from 24% to 32% at the mean optimum rate of 200 lb/A.
When N rates exceeded optimum the proportion of green tomatoes increased and soluble solids decreased.
P addition did not affect soluble solids.
For both tomatoes and peppers, rates of N above optimum tended to dramatically increase residual soil nitrate.