View Poster Application


Applied Research

Stephanie Karhoff
Field Specialist, Agronomic Systems
The Ohio State University


Wet weather conditions in the spring of 2019 prevented Ohio farmers from planting over 1.5 million acres. A decline in beneficial mycorrhizal fungi that aid in plant water and nutrient uptake may occur in absence of host root tissue in fields left unplanted. It is hypothesized that corn (Zea mays) planted into these fallow fields may exhibit nutrient deficiencies due to a reduction in mycorrhizal root colonization. This phenomenon is commonly referred to as fallow syndrome. Fallow syndrome is poorly reported in Ohio, and few on-farm studies have been conducted to justify potential remediation options. The objective of this study was to assess the efficacy of starter phosphorus applications and microbial inoculants on reducing the impacts of fallow syndrome in corn. Starter phosphorus fertilizer (7-16-3 at 5 gal/ac); 3Bar Bio-YIELD® microbial inoculant (Pseudomonas brassicacearum); Valent MycoApply® EndoPrime® SC mycorrhizal inoculant (Glomus spp.) was applied at planting in May 2020 to evaluate their impact on corn growth and yield after a year-long fallow period. Soil samples taken at planting revealed phosphorus levels of 26 ppm Mehlich-3. Aboveground tissue was collected from each plot between V4 and V6 growth stages to estimate biomass and nutrient uptake, and the trial was machine harvested in November 2020. Plots treated with starter phosphorus alone or in combination with either inoculant had significantly higher individual plant biomass and lower phosphorus tissue content than the control treatment where no phosphorus was applied. However, starter phosphorus and inoculants did not significantly increase yield when compared to the no-phosphorus control. There was no evidence of fallow syndrome at this site, despite soil test phosphorus levels being within the recommended range. Overall, these data will inform future management recommendations to growers planting corn after a fallow period.

Poster has NOT been presented at any previous NACAA AM/PIC

This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.

Click to view Poster

Authors: S. Karhoff, C. Schroeder, S. Culman, E. Hawkins
  1. Karhoff, S. OSU Extension Educator, Ag and Natural Resources, Ohio State University Extension Williams County, Ohio, 43506
  2. Schroeder, C. OSU Extension Educator, Ag and Natural Resources, Ohio State University Extension Allen County, Ohio, 45804
  3. Culman, S. Associate Professor, School of Environment and Natural Resources, Ohio, 44691
  4. Hawkins, E. Field Specialist, Agronomic Systems, The Ohio State University, Ohio, 45177