Nutrient Replacement Strategies for Hydroponics

Project Overview

Project Type: Farmer
Funds awarded in 2024: $29,084.00
Projected End Date: 03/31/2026
Grant Recipient: Levo International, Inc.
Region: Northeast
State: Connecticut
Project Leader:
William Heiden
Levo International, Inc.
Nathaniel Heiden
Levo International, Inc.


  • Vegetables: greens (lettuces), peppers


  • Production Systems: hydroponics

    Proposal summary:

    Levo International, Inc. (Levo) is a 501(c)3 nonprofit with the
    main objective to provide food security solutions for families.
    Hydroponic agriculture is the main mechanism we use to promote
    this objective. Hydroponics is the growth of plants in a
    water-based nutrient solution, without the use of soil. We both
    run local hydroponic farms and support local growers to start
    their own small-scale farms. Hydroponics is a sustainable form of
    agriculture which can be used on nonarable land and enables
    efficient use of water and fertilizer in a closed loop. High
    start-up costs and complexity of operation render hydroponics
    inaccessible for many. Our research focuses on developing and
    deploying hydroponic systems that are simpler and less expensive
    to build and operate.

    It is standard practice in hydroponic production to either
    regularly replace the nutrient solution or to frequently complete
    expensive analysis of the ion content of the nutrient solution
    and inject individual nutrient salts accordingly. In a recently
    published research project, we produced greens and fruiting crops
    in our hydroponic systems without replacement of the nutrient
    solution. This approach enables us to conserve water and
    fertilizer. This proposed project will enable us to pilot the
    implementation of this more sustainable and efficient approach.
    Through the proposed research we will gain directly applicable
    data about how we can adjust nutrient additions for different
    crops, how yields change without replacement of the nutrient
    solution and the risk of disease pressure if the nutrient
    solution is not replaced.

    Project objectives from proposal:

    Our first objective (Obj. 1) is to determine the
    concentration of macronutrients over time in nutrient solutions
    which are, or are not, replaced.
    We hypothesize that
    macronutrients decrease in a consistent pattern over time and
    that measurements of electrical conductivity (E.C.) and total
    dissolved solids (TDS), which provide an estimate of the total
    concentration of ions in the solution, can be used to estimate
    when nutrients should be added.

    Our second objective (Obj. 2) is to test the hypothesis that
    reuse of nutrient solution decreases the inputs of fertilizer
    and water sufficiently that it justifies decreased yields
    To test this hypothesis, we will conduct yield trials at three
    different Levo farm locations in which nutrient solutions are
    replaced every 3 weeks, or they are not replaced for the duration
    of a crop.

    Our third objective (Obj. 3) is to record the incidence of
    disease over 2 growing seasons in systems described in objective
    two. We hypothesize that due to the rapid multiplication and
    spread of root rot causal agents such as Pythium, recycling of
    the nutrient solution will not lead to greater risk of

    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.