Vermicompost as a fast-acting nitrogen amendment to mitigate nitrogen deficiencies in organic vegetable production
Vermicompost is regarded as a fast acting, but expensive, nitrogen amendment. Its use may become more prevalent when Chilean Nitrate is decertified. We tested whether Vermicompost could improve productivity and whether it prevented early season deficiencies in a model crop (Swiss Chard) at Bella Farm owned by our partner Rachel Schattman. Experimental treatments were: Direct field-seeded Swiss chard with banded vermicompost, banded compost and a control which received no starter fertilizer; Swiss chard starts produced in growing medium with 10% vermicompost, 20% compost and no compost. The starts were transplanted after all start treatments had reached sufficient size for transplanting. Throughout the growing season we measured plant size. At the end of the growing season we measured harvestable biomass. ANOVA suggested that there were differences among treatments inharvestable biomass. Means were not significantly different among the direct seeded treatments although the vermicompost produced the greatest biomass. For transplants, vermicompost produced significantly greater biomass than any of the other treatments. Presently, tissue samples are being processed for nutrient analysis.
1. Establishing 24 research plots at Bella Farm and 2. Direct seeding and preparation of greenhouse starts. Twenty four plots were established at Bella Farm. There were 4 replicates of six treatments: Direct field-seeded Swiss chard with banded vermicompost, banded compost and a control which received no starter fertilizer; transplanted Swiss chard starts produced in growing medium with 10% vermicompost, 20% compost and O compost.
3. Measurement of soil water NO3 and NH4, extracted from soil water samplers installed below the root zone, after storm events. Very few events produced leachate as the plots were on a Vergennes Clay soil. We noticed that during heavy rainfalls, the plots produced much runoff suggesting slow info=iltration rates. However there were several events that produced leachate and samples were collected then. These samples are presently frozen awaiting analysis.
4. Estimate of plant nutrient deficiencies. Visual inspection of plants was done on the plots to detect any deficiencies and plant sizes measured to estimate growth rates.
5. Estimate of early nutrient supply rates using Plant Root Simulator samplers. Plant Root Simulators could not be installed into the plots as the clay soil was too hard and dry during the growing season. . However, we will be investigating supply rates in lab mesocosms to better understand the pattern of release from a clay loam.
6. Maintaining a project blog. The blog can be found under http://vermicompostingne.wordpress.com/
The blog has been updated with growing season pictures and results. We will continue updating as more resuts become available.
7. Presenting the project to 1 regional and 1 national conference. Presentations are planned for the SSSA meetings in November 2014 and the summer NOFA conference.
March 2013 – March 2014: Maintaining a project blog.
Blog was maintained through June 2013 and is curretly being updated with information on yield results and pictures of how the crops were developing in the different treatment plots .
March to April 2013: Establishment of plots, soil fertility analyses, installation of lysimeters, seedbed preparation, seeding crop, vermicompost, compost application in plot study.
Plots were established in June rather than April because of the heavy rains in 2013. We established plots at Bella Farm but also at two additional sites with different soils. At the additional sites we only direct seeded soils. Lysimeters were installed in June.
March 2013 to December 2013: Sampling lysimeters in plots.
Lysimeters were sampled from June to November. Early frost required us to remove the lysimeters early. Lysimeters at Bella did not yield much percolate for chemical testing. We think this was due to the clayey nature of the soil. The samples that we did retrieve are presently frozen and are awaiting analysis.
April 2013- May 2013: Seed crop in greenhouse and direct sow in field.
We started seeds in May 2013
May 2013: Transplanting greenhouse starts. Greenhouse starts were transplanted at the end of June.
May 2013- March 2014 Interpretation of data. We found that there were significant differences among treatments but that the harvestable biomass differences were only significantly different for the greenhouse starts grown in 20% vermicompost. Preliminary economic analysis showed a potential 30% increase in profits when using vermicompost inspite of hte high cost of the amendment.
June 2013 to September 2013: Visually assessing crop nutrient deficiencies, plant analyses. Plant tissue analyses are in progress. The Plant and Soil science grinding room is being refitted with safety equipment which has delayed the analyses.
September 2013 – October 2013: Harvest crop, plant analysis. Soil fertility analysis. Crops have been harvested, fresh harvest weight and plant heights have been recorded.
Data collection was not complete for the ASA 2013 Annual Meeting and the NOFA 2014 Winter Conference. We will request a no-cost extension to present data at the ASA meetings in the Fall of 2014 and at the NOFA Summer Conference. This was due to safety issues in the UMV grinding facility. Grinding is required for analysis. The gridning room is to reopen in April 2014 and the analysis will be done soon after.
Impacts and Contributions/Outcomes
Research data was presented at a departmental seminar by Peter Austin.
Data was also used to demonstrate differences between vermicomposting and composting to students in “Fundamentals of Soil Science” with 92 enrolled students
Research data and images from the field trials were shown at UCONN’s Worm Day for Master Composters on October 12, 2013
University of /vermont
Plant and Soil Science
Burlington, VT 05405