Efficacy and cost effectiveness of foliar nutrient applications to vegetable crops on a large Rhode Island farm

View the project final report

Commodities

• Vegetables: tomatoes

Practices

• Crop Production: foliar feeding
• Farm Business Management: budgets/cost and returns

Rhode Island vegetable farmers need to maximize profits on limited cropland. Foliar nutrient application is a
popular production practice. Extension publications recommend this practice only under conditions of stress or
suspected deficiency, yet according to a recent informal survey in RI, it is routinely used as regular production
practice on conventional farms. While positive results are sometimes observed, its cost-effectiveness is unknown,
though it may be warranted in high tunnels where land is limited.

Efficient input use is a key factor of economic sustainability. Qualified professionals can provide guidance towards
this end. The objectives of this project are to: 1) test a set of foliar nutrient application practices recommended by
a fertilizer company representative for a) efficacy and b) cost-effectiveness and 2) survey RI conventional growers
on their fertilizer decision-making process in order to design effective educational programming.
On Confreda Farm, three succession plantings of determinate tomatoes will be split, half receiving prescribed
nutrient sprays, half without. Leaf tissue nutrient status and percent marketable yield will be measured. A field plot
study at URI will duplicate the farm study. For both components, input costs and potential revenue per acre will be
extrapolated for comparison. At a winter meeting in which the subject is discussed and results reported, growers
will be asked to complete a survey on their fertilizer decision-making processes to assess educational needs. A
ten-minute video on the subject of foliar nutrient application for vegetable growers will be created, along with an
extension fact sheet.

The aim of this investigation is to improve profitability and environmental sustainability among conventional Rhode Island vegetable growers through examination of fertilizer nutrient delivery to vegetable crops. Two hypotheses
will be addressed:
1) Routine applications of foliar fertilizers to field-grown determinate tomatoes provide significant return on
investment
2) Foliar nutrient applications can be used to correct deficiencies in field-grown determinate tomatoes, particularly
of nitrogen and potassium
Yield and leaf tissue parameter monitoring will determine if supplemental foliar-applied nutrients are necessary as
routine production practice, or only useful when deficiencies have been diagnosed through tissue sampling. In
particular, cost-effectiveness of the routine use of these products will be assessed.
The issue of information sources and their quality will be addressed in a grower survey designed to answer the
following question:
3) How do growers arrive at their decisions to adjust inputs for vegetable crops which they have been producing
as a part of their mix of crops?
The objective of the survey component is to ascertain whether growers are being reached by professionally
qualified purveyors of relatively unbiased, science-based information. If they are not, the survey will explore
reasons for this disconnect.