Nitrogen dynamics and yield response to minimal supplemental heating in high tunnel winter production

Project Overview

Project Type: Partnership
Funds awarded in 2017: $14,997.00
Projected End Date: 12/31/2019
Grant Recipient: Cornell University
Region: Northeast
State: New York
Project Leader:
Ethan Grundberg
Cornell Cooperative Extension Eastern New York Commercial Horticulture Program


  • Vegetables: greens (leafy), greens (lettuces)


  • Crop Production: fertilizers, high tunnels or hoop houses, nutrient cycling, nutrient management, organic fertilizers
  • Soil Management: nutrient mineralization

    Proposal abstract:

    Winter vegetable production in minimally heated high tunnels is becoming more popular in the Northeast as farms
    attempt to increase farm income and maintain customer relationships through the winter. However, little
    information exists on the relationships between temperature, nitrogen availability and uptake, marketable crop
    yield, and economics for winter growers. This project proposes to study two anecdotally popular temperature
    settings in identical, side-by-side tunnels for winter production and track the differences in propane use, soil
    temperature, soil nitrate availability, nitrogen uptake, and crop yield of the popular winter grown vegetables
    Winterbor kale, spinach, and mesclun lettuce mix. Collecting this data will allow us to assess the return on
    investment of supplemental heating and enhance our understanding of nitrogen cycling in heated high tunnels
    during the winter to better inform fertility management practices. The conclusions of the investigation will be
    shared immediately amongst Cornell Cooperative Extension specialists to improve technical assistance to winter
    growers as well as disseminated directly to farmers via trade publications and presentations at conferences. In
    total, over 1000 growers will receive this information allowing them to make better-informed decisions about
    whether supplemental heating for winter production is a sound economic choice.

    Project objectives from proposal:

    The Poughkeepsie Farm Project erected two identical 42’ x 196’ side-by-side high tunnels in 2016 that are
    equipped with high efficiency Modine 93 propane heaters. By using identical planting dates, fertilization rates, and
    crop mixes in the two houses, it is possible to measure and compare the impact on marketable yield and nitrogen
    availability and uptake in two different temperature zones. One house will operate with the thermostat set at 35-
    degrees Fahrenheit while the second house operates at 42-degrees Fahrenheit. Installing in-line propane meters
    in each house will allow for precise monitoring of fuel use and allow for a cost comparison at the end of the study.
    Soil nitrate level tests and plant tissue sampling paired with soil temperature monitoring will demonstrate any
    difference in nitrogen availability in the soil and actual plant uptake in the two temperature zones. This information
    will allow farmers using season extension techniques to make more informed decisions about the costs and
    benefits of heating to two different thresholds and impacts on nutrient management strategies under different
    temperatures in high tunnels.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.