Submission Date
5-4-2026
Document Type
Paper- Restricted to Campus Access
Department
Biology
Adviser
Denise Finney
Committee Member
Anthony Lobo
Committee Member
Leslie New
Department Chair
Denise Finney
Project Description
The application of carbon to agronomic crops via soil application of molasses has become common. Farmers claim that molasses promotes soil health. However, there is a lack of evidence to support this claim. The goal of this project is to investigate the impacts of molasses application on indicators of soil health. We hypothesized that field rates of molasses addition would not increase microbial respiration, nitrogen mineralization, and microbial biomass in soil. Molasses was added to soil incubations in decreasing concentrations: 1.2 mg C/g soil (laboratory), 0.6 mg C/g soil (half), 0.1 mg C/0.001 mg C/g soil (field), and no carbon addition (control). Over the four-week incubation, microbial respiration was measured. After two weeks and following termination of the incubation, nitrogen mineralization and microbial biomass were determined. Results indicated a significant treatment effect with laboratory and half molasses addition average microbial respiration rates being higher than field and control. Additionally, there was no difference between field rates and control at any point over the four-weeks. The control, half, and lab treatments had significantly greater ammonium concentrations compared to field and intermediate treatments. Control, field, and intermediate treatments had a significantly higher concentration of nitrate compared to half and lab treatments. Field treatments had significantly higher microbial biomass compared to the intermediate and lab treatments. There was no significant difference in microbial biomass between field and control treatments. The high concentration of ammonium and low microbial biomass in half and lab treatments may indicate the suppression of the nitrification process, potentially through inhibition of nitrifying bacteria.
Recommended Citation
Markley, Lauren, "Field Rates of Soil Carbon Addition in the Form of Molasses May Not Support Soil Health Indicators of Microbial Respiration, N Mineralization, or Microbial Biomass" (2026). Biology Honors Papers. 114.
https://digitalcommons.ursinus.edu/biology_hon/114
