Vermicompost as a fast-acting nitrogen amendment to mitigate nitrogen deficiencies in organic vegetable production

Final report for ONE13-182

Project Type: Partnership
Funds awarded in 2013: $14,588.00
Projected End Date: 12/31/2014
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Project Leader:
Dr. Josef Görres
University Of Vermont
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Project Information

Summary:

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 (at the P ‹ .05 level) 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.

Economic Analysis showed that in directly seed plots, applications of vermicompost was only more profitable in very sandy soils. It is not clear why this is but leaching and or droughty conditions in the sandy soil may have allowed vermicompost to out compete the other treatments. However, when looking at a comparison between crops that were either directly seeded or planted from greenhouse starts, the vermicompost improved economic returns when starts were produced with vermicompost. It also appears that vermicompost use to produce greenhouse starts can shorten teh maturation time of Swiss chard, a large benefit where growing seasons are short.

Analysis of soil nitrogen and soil water nitrogen did not show any significant differences. There are several more samples to be analyzed to confirm this finding.  Background information on vermiculture and results are depicted and explained at blog http://vermicompostingne.wordpress.com/

Introduction:

For sustained production, organic agriculture depends on plant needs being synchronized with the release of nutrients from organic amendments during decomposition within the soil. Like conventional agriculture, organicagriculture also requires nutrient inputs as organic amendments as harvest and other nutrient losses lead to a reduction of fertility. Unlike conventional agriculture, organic fertility management has to be planned well ahead of when plants need the nutrients. For example, inputs of composted materials will produce plant available nutrients through decomposition and mineralization only after a time. Because decomposition is strongly dependent on soil moisture and temperature, nutrient needs may not always be met as planned or synchronous with plant need. Yet, plant nutrient deficiencies that result have to be addressed to maintain an economic level of yield. Unlike conventional agriculture, fast acting amendments are not readily available. Until recently organic farmers could fall back on Chilean nitrate to combat early nitrogen deficiency. As of October 2012, Chilean nitrate is no longer certified in organic production. This leaves a significant gap in organic fertility management in particular where spring weather conditions may prevent timely decomposition and mineralization of organic amendments and cover crops. Until this year it was allowed in several northeastern states for use to satisfy up to 20% of total plant requirements.

Farmers are looking for an organic, fast acting form of nitrogen to replace Chilean nitrate, a mineral, available form of nitrogen. Because of its high nitrogen content (reference 1,2,3, below) VC may be able to fulfill the function of Chilean nitrate. In addition to a fertility analysis, economic analysis is needed to evaluate feasibility as VC is expensive. Our goals are to show that VC may as a soil amendment prevent nutrient deficiencies; to measure nutrient leaching; to compare cost and benefits of using VC; to transfer this knowledge to the organic farmers. VC provides additional services beyond soil fertility. These include prevention of disease (4), increased germination rates, resilience to pest outbreaks (5). While we do not directly test for these, they may be expressed in greater yield and thus in the economic analysis. VC has been shown to increase yield in crops (6).

Additionally vermicomposting is aligned with sustainable agriculture practices. In a greater context, VC and TC both recycle organic waste materials bringing them back to the farm. Vermicomposting uses epigeic earthworms, such as Red Wigglers (Eisenia fetida) to decompose farm, food and animal wastes. The resulting compost is high in available nitrogen and has C:N ratios of about 15:1. By pretreating organic wastes at temperatures between 45-65°C, organic standards of pathogens and weed seeds suppression can be met. Like TC, VC has high organic matter, water holding capacity and nutrient retention. Thus resiliency of the agroecosystem, both above-ground production and below-ground decomposition is increased while nitrogen leaching may be reduced. In preliminary trials at the UVM Horticulture Research Facility with spinach, we found that VC produced greater germination rates and longer deeper roots, as well as lower incidence of N deficiency than TC, Chilean nitrate and control. We found that the effect of VC was greater on the droughty side of the field suggesting that VC may indeed impart some drought resistance to the agroecosystem. Much of the evidence that VC has benefits in crop production comes from studies on seed germination and production of starts in greenhouses. Yet, there is a dearth of information derived from field studies. We propose to implement field plot trials with both starts grown in greenhouses and directly seeded crops to test hypotheses on fertility, economics and environmental impacts.

1. Atiyeh, R. M., Subler, S., Edwards, C. A., Bachman, G., Metzger, J. D., & Shuster, W. 2000. Pedobiologia, 44(5):579-590 2. Frederickson, J., Howell, G., & Hobson, A. 2007. Eur. J. Soil Biol., 43(1):S320-S326. 3. Lazcano, C., Gómez-Brandón, M., & Domínguez, J. 2008. Chemosphere, 72(7):1013-9. 4. Gopal M., A. Gupta, E. Sunil, G.Thomas. 2009. Curr. Microbiol. 59:15-20. 5. Arancon N.Q., C.A. Edwards, T.J. Oliver, R.J. Byrne. 2007. Crop Prot. 26:26-39. 6. Arancon N.Q. and C. A. Edwards. 2011.In: Vermiculture Technology (Edwards,Arancon, and Sherman eds.).pp 129 – 148. CRC Press, Boca Raton.

Project Objectives:

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 infiltration rates. However there were several events that produced leachate and samples were collected then. There was no signficant difference in soil water nitrogen among the different treatments. A similar outcome was found for soil nitrogen concentrations.

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/

7. Presenting the project to 1 regional and 1 national conference.

Cooperators

Click linked name(s) to expand
  • Peter Austin
  • Rachel Schattman

Research

Materials and methods:

Vermicompost will be obtained from our partners at VermiVision of Palo Alto California and compost from the Highfields Center of Composting in Wolcott, Vermont. Both products are quality controlled and fertility data is available although we will test their compost prior to using them in this study.

Field plots will be established at our collaborator’s farm. The study is designed to compare the effect on crop growth of VC with the effect of TC and the effect of doing nothing (C for control). These primary treatments will be implemented in two forms: directly seeded DS) and transplanted greenhouse starts (GS) to give a total of 6 treatments (VC X DS, TC X DS, C X DS, and VC X GS, TC X GS, C X GS). The design will have four replicates of each treatment. Two long, parallel seedbeds (1-m wide) will be prepared. 12 plots (2m by 2m) will be installed in each seed bed. Primary treatments VC, TC and C will be arranged in a stratified random fashion (four blocks of 3) along the seed beds. These will be arranged for a pairwise comparison of corresponding DS and GS treatments in the two parallel seed beds. DS and GS will be placed randomly in either the first or the second seed bed (Table 1). There will be a 1 m buffer between each plot and seedbed.

The soil will be characterized for texture, organic matter content, density and saturated hydraulic conductivity at 20 cm depth increments to a depth of 60 cm. Unsaturated conductivity will be estimated using the soil hydraulic properties calculator. In addition Watermark sensors will be used to log soil matric potential. These data will be used to parameterize, calibrate and validate a soil water flux model (Hydrus) for estimation of nitrogen leaching from the field.

Table 1: Randomized pairwise linear block design to compare compost treatment effects and seed starter method.
Plot 1 2 3 4 5 6 … 12
VCXDS TCXGS CXDS TCXDS CXGS VCXGS … TCXGS
VCXGS TCXDS CXGS TCXGS CXDS VCXDS … TCXDS

Crop: Swiss Chard (beta vulgaris, var: Large White Ribbed). Large White Ribbed was selected as it can withstand frost and does not bolt in the summer like some other varieties do when exposed to frost early in the season. This characteristic will make it easier to synchronize the plant growth stages of greenhouse started and directly seeded chard.

Greenhouse start production: A mixture of 50% compost (VC or TC) and 50% conventional organic growing medium (such as coir) will be placed into trays for starter plugs (5-cm deep, 1-inch wide wells). Plugs will be started in late April. For the control, only the conventional growing medium will be used. Seedlings will be planted by hand in the field after May 31when plants are 2 inches in size before transferring them to the field. In-row spacing will be 30 cm and between-row spacing will be 50 cm allowing 2 rows of crops in each seedbed.

Direct seeding: Direct seeding will be accomplished with a precision seeder placing seeds into rows prepared with VC, TC or no amendment. VC and TC rates will be calculated based on inorganic nitrogen analyses for the composts and soils to satisfy 20% of nitrogen as inorganic N. Prior to planting seedbeds will be prepared according to recommendations for swiss chard. Chard seeds will be spaced in the field at distances of 10 cm within the row with rows separated by 50 cm, and subsequently thinned to an in-row spacing of 30 cm. The seeds will be placed in the field in mid-May.

Actual methods timeline:

January to April 2014: Data collection continued.

April to December 2014: Grinding of plant materials, analysis of soil and water samples.

Samples were from 2013:

March 2013 – March 2014: Maintaining a project blog

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 them 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/

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.

November 2013. Presenting data at the annual meeting of the Agronomy Society of America.

Data collection was not complete for the ASA 2013 Annual Meeting and the NOFA 2014 Winter Conference. 

Research results and discussion:

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 (at the P ‹ .05 level) 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.

Economic Analysis showed that in directly seed plots, applications of vermicompost was only more profitable in very sandy soils. It is not clear why this is but leaching and or droughty conditions in the sandy soil may have allowed vermicompost to out compete the other treatments. However, when looking at a comparison between crops that were either directly seeded or planted from greenhouse starts, the vermicompost improved economic returns when starts were produced with vermicompost. It also appears that vermicompost use to produce greenhouse starts can shorten teh maturation time of Swiss chard, a large benefit where growing seasons are short.

Analysis of soil nitrogen and soil water nitrogen did not show any significant differences. There are several more samples to be analyzed to confirm this finding.  Background information on vermiculture and results are depicted and explained at blog http://vermicompostingne.wordpress.com/

Research conclusions:

For transplants, vermicompost produced significantly greater biomass than any of the other treatments and this increase was economically beneficial.  For direct seeding, it appears that using vermicompost in very sandy soils may prove economical.  It is not clear why this is but leaching and or droughty conditions in the sandy soil may have allowed vermicompost to out compete the other treatments. However, when looking at a comparison between crops that were either directly seeded or planted from greenhouse starts, the vermicompost improved economic returns when starts were produced with vermicompost. It also appears that vermicompost use to produce greenhouse starts can shorten the maturation time of Swiss chard, a large benefit where growing seasons are short.

Participation Summary
1 Farmer participating in research

Education & Outreach Activities and Participation Summary

3 Webinars / talks / presentations
1 blog was maintained 2013 to 2014 http://vermicompostingne.wordpress.com/

Participation Summary:

1 Farmers
1 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

Presented information at University of Vermont class “Fundamentals of Soil Science” with 92 enrolled students.

Presentations were given at workshops for University of Connecticut Master Composters in the Fall of 2013 and 2014. 

Learning Outcomes

1 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

Some of the research results have been used to show the benefits of Vermicomposting in the UVM class “Fundamentals of Soil Science” with 92 enrolled students.

Some of the research was presented to master composters at the University of Connecticut on October 12, 2013.

My graduate student Peter Austin is preparing his thesis. He will defend at the end of February. His thesis will be uploaded with the final report.

Project Outcomes

Project outcomes:

Areas Needing Additional Study

The economic cost-benefit analysis of vermicompost can simply be broken down into inputs and outputs; what is the cost of the material going into the system and what is the output leaving the system (sales). However, in any cropping system there are multiple variables (direct and indirect) to monitor and analyze to get a sound understanding of economic inputs and outputs. Direct variables include the required nutrient content to meet crop needs (fertility amendments), the cost of material, means of application, time of production/plant development and yield. Indirect variables would affect or be affected by the amendment but not directly associated with amendment costs and yield, for example: soil quality, irrigation, disease/pest management, cultural practices (legume cover crop rotations, tillage practices, etc.) and environmental risks. All of these variables must be taken into consideration when determining the usefulness of vermicompost as a nitrate amendment in New England. Investigating these variables in field trials is important to obtain a full picture of the cost of using vermicompost. It is also important to research the source of compost to understand how quality control is monitored and maintained in the production of vermicompost or any other organic amendment. Getting a consistent, stable, quality product must be trusted by the manufacturer to the farmer. Understanding how the amendment is produced and with what raw materials is crucial in replicating high quality soil amendments. Quality control on farm can be done by germination tests, rate of development monitoring, and integrated pest management monitoring done consistently on the farm to ensure that the quality of product being purchased is meeting the needs of the farmer.

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.