Investigating effects of beneficial microbial inoculants on potatoes

Project Overview

Project Type: Farmer
Funds awarded in 2011: $3,798.00
Projected End Date: 12/31/2011
Region: Northeast
State: New York
Project Leader:
Marina Michahelles
Shoving Leopard Farm

Annual Reports


  • Agronomic: potatoes


  • Crop Production: biological inoculants, foliar feeding, nutrient cycling, application rate management
  • Production Systems: general crop production
  • Soil Management: soil analysis

    Proposal summary:

    We propose to study the effects of beneficial microbial inoculants on Red Norland potatoes. Previous research shows that symbiotic relationships exist between certain plants and various soil microbes, including some nitrogen-fixing bacteria and fungal mycorrhizae. The Real Food Campaign in the Northeast has been promoting the use of several microbial inoculants as part of healthy and sustainable soil fertility management. We will compare the emergence, growth, leaf sap and tuber Brix measurements, soil conductivity, plant longevity, yield, as well as tuber flavor and texture of potato plants treated with a mixture of beneficial microbial inoculants against an untreated control. A positive outcome would suggest a potential increase for farmers in plant health, yield, and nutritive value, all of which could result in increased income to producers. Description of problem One problem every farmer faces is supplying adequate nutrition to the plants and animals he or she is raising. Not only do we have to compensate for our soil’s natural deficiencies and mineral imbalances, but we also have to re-supply nutrients we remove through harvest. A second problem, which Shoving Leopard Farm shares with many other farms, is limited space; we have to maximize production on our acre-and-a-half. To address both these limitations, we hope to enlist the help of beneficial soil microbial communities that have been shown to promote for plant nutrition and health. Soil biologists now have a greater understanding of the role that living soil organisms - from bacteria, yeasts and fungi to actinomycetes and algae - play in plant nutrition. Some bacteria are responsible for fixing nitrogen; some are associated directly to legume root hairs and provide plants with useful nitrogen; others are free-living; while still others decompose chitin and cellulose. Several fungi are known to have strong symbiotic relationships with plants and in the absence of any of these, plants are shown to have lower yields and poorer quality. The activities of soil microbes increase plants’ access to nutrition, resulting in more pest-resistance, higher nutritive value, and greater resilience in drought and frost. Diverse soil biological communities in agricultural systems improve both yield and quality of produce.

    Project objectives from proposal:

    Shoving Leopard Farm has been growing mixed vegetables and fresh cut flowers since 2006 on 1.5 acres of heavy clay. Save for the work the rototiller does to prepare beds in spring and fall, all work is done by hand. We have improved the soil tilth through applications of finished compost, green manure, and hay mulch and have seen an improvement over the years in terms of production and plant health. We want to study the effects on crop yield (measured in quantity and weight) and quality (measured in Brix) by the promotion of soil biological communities by inoculating seeds and soil with beneficial species of bacteria, mycorrhizae, and other microbes. If this study shows positive results, other farms could increase their crop production without increasing land-use, and possibly decrease their use of some fertilizers over time.

    The Real Food Campaign has been offering courses in the Northeast on how to increase the nutrient value of the crops we raise by, not only addressing the underlying deficiencies and relative imbalances of nutrients in the soil, but also by introducing and promoting soil biology. Scores of farmers have already begun using the biological inoculants the associated company, Nutrient Density Supply Company, sells. This study is designed to evaluate the effect of these inoculants on Red Norland potatoes grown on our CSA farm.

    The plants used for the study will be Red Norland potatoes because potatoes have shown a positively response to inoculation in the past (LNE03-179), and because we grow several rows of them so test plots can be distributed randomly. A saturated paste analysis and a Cornell Soil Health test will be done in April, 2011 and again in April, 2012 for a complete assessment of soil health and fertility.

    The trial will compare Red Norland potato plants with no treatment (Control – C) to plants with our usual use of fish/kelp emulsion at planting, and foliar spray of fish/kelp emulsion and Sea Agri sea salt (Treatment 1 – T-1), and to plants with our usual treatment plus Nutrient Density Supply Company bio-inoculatants (Treatment 2 – T-2), and to plants that only receive bio-inoculants (Treatment 3 – T-3). Potato seed will be planted in mid-April and will be harvested in mid-September. There will be 22 weeks of in-field treatment and data-collection.

    Three plots of each (total twelve plots) will be 3 ft x15 ft and their location within the beds will be randomized. Flags will be used to delineate treatment area, and maps will be made for records.

    All T-2 and T-3 seed will be inoculated with “Mycotonic” and “Biogensis III”, which include mycorrhizae and bacteria. Control and T-1 seed will not be inoculated.
    At planting, control plants will be watered in, T-1 plants will be watered in with fish/kelp emulsion, and T-2 plants will be watered in with fish/kelp emulsion and “Biogenesis”, which includes beneficial microbes, and “Pepzyme”, which is a microbial stimulant. T-3 will be watered in and receive “Biogenesis” and “Pepzyme” at planting.

    Both T-1 and T-2 plots will receive weekly foliar spray and soil drench with fish/kelp emulsion and sea salt throughout the season. T-2 and T-3 plots will receive inoculants at these times. Control plots will receive no foliar spray, but will receive water instead of drench.

    The following measurements will be made for each plot:

    • Days to emergence;
    • Weekly measurements of: soil conductivity - 3 samples per plot, leaf sap Brix - 3 samples per plot;
    • Biweekly measurements of growth: height, stem thickness;
    • Size, weight, number, tuber Brix at harvest;
    • Plant longevity;
    • Cornell soil health test;
    • CSA members blind taste test

    Results will be interpreted using SPSS.

    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.