Polyculture Market Garden Study: Year 5 results

Paul Alfrey - The Balkan Ecology Project
Friday, 31st January 2020

Paul Alfrey from the Balkan Ecology project shares the results from Year 5 in their polyculture market garden study - research showing the huge value of diverse growing systems.

Here are the results from the fifth and final year of our Market Garden Polyculture Study. This study looks at the differences between growing annual vegetables and herbs in polycultures vs growing them in traditional blocks. Although this was the final year of this study, we are just getting started and next year we will be continuing our polyculture study focusing on the productivity of perennial forest gardens and biodiversity within the gardens. Registration for next year's study is now open and you can find out more about that here.

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We'd like to say a huge thank you to the 2019 crew that joined us for the study this season and that make it possible for us to carry out our experiments and research. Thank you all for your valuable input, it was our pleasure to host you and we look forward to seeing you again some day.
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The 2019 Polyculture study crew

Garden Overview 

Location: Bulgaria, Shipka
​Climate: Temperate
Köppen Climate Classification - Dfc borderline Cfb
USDA Hardiness Zone: 5b - 7a
Latitude: 42°
Elevation: 565m
Average Annual Rainfall: 588.5mm
Prevailing Wind: NW & NE
Garden Name: Aponia - Polyculture Market Garden 


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The six longer beds in the left hand corner of the photo on the right (the Aceaes) are the trial beds, the focus of this study. You can find the location of the Polyculture Market Garden on google maps here (labelled as Aponia on our Project map).


Garden area: 256.8m2
Cultivated beds area: 165.6 m2
Paths: 50cm wide - 91.2m2
Bed Dimensions - 23m x 1.2m  Area - 27.6m2 per bed
Number of beds: 6

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The beds are named after common vegetable families in order to familiarise participants with the use of Latin and introduce them to some major plants families. The bed names do not correspond to what is planted in the beds.


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The Polycultures 

We experiment with many polycultures and have developed a categorisation system for ease of reference. They are categorised by life cycle i.e annualperennial or combi (annuals and perennials) and further categorised by function. i.e supportinfrastructure or production. Often a polyculture will provide multiple functions, but the primary function is what sets them to each category. I give all our polycultures nicknames. For example, all polycultures in the annual and production category are named after Stoic Philosophers.
The study is based on a polyculture I call Zeno, an annual/production polyculture. As we are looking to see how polycultures compare to conventional growing we also include a control for the Zeno polyculture i.e. the same crops from Zeno but planted in a more conventional block pattern. In the below illustration you can see the planting plan of the trial beds.

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We scaled down to one bed of each polyculture and one bed of control for Zeno this year as opposed to two of each as seen above. We have extrapolated from the data we recorded from each bed to keep the results comparable to the previous years where we were growing on four beds.

Polyculture Zeno

We've been growing Zeno in the garden for around 11 years now. It's been very successful in our home gardens and in 2015 we scaled it up for the market garden.

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For more info on plant spacing, management and maintenance of this polyculture see a previous post here.


Zeno Plant List  - The following plants and cultivars were used in this polyculture;

Tomato - Solanum lycopersicum 'Tigerella'
Tomato - Solanum lycopersicum 'Ukranian purple'
Tomato - Solanum lycopersicum 'Yellow Pear'
Tomato - Solanum lycopersicum 'Chocolate Pear'
Tomato - Solanum lycopersicum 'Alicante'
French Beans - Phaseolus vulgaris 'Cobra'
French Beans - Phaseolus vulgaris - Local
Courgette - Cucurbita pepo 'Black Beauty'
White Bush Scallop - Cucurbita pepo
Squash - Cucurbita pepo 'Waltham Butternut'
Basil - Ocimum basilcium 'Sweet Genovese'
Pot Marigold - Calendula officinalis 

Zeno Planting Scheme  

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Zeno Control  

The control includes all of the above plants but planted in blocks along the bed (see below). We want to see how the two planting schemes compare, i.e. whether or not the polyculture will produce more and the difference in the amount of time needed to cultivate the different layouts. The fertility inputs for both beds are the same.

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The table below shows the plant species composition of each of the beds including the dates that the plants were sown or planted.

We have not included a list of native wild plants that are encouraged to grow around the perimeter of each bed that we mow and apply as mulch to the beds during the growing season.

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What we Record - Inputs 

Time Input - We record how long it takes to develop, maintain and manage the garden. The time is recorded for each task starting from sowing the seeds, preparing the beds, planting and caring for the plants, harvesting, preparing for market and packing away. The time taken for each task is rounded up or down to nearest minute. Nearly all of the records are based on two people carrying out each task unless otherwise stated in the record sheet. 
Fertility Inputs - All fertility additives are recorded including; seed sowing mediums, composts, mulch, and ash.

Financial Inputs, Costs - The costs associated with the garden are recorded. We do not cost the time spent on the garden but do provide estimates of the time the activities take. Set up and tool costs were included in the first year records. This year we only recorded operating costs. 
N.B. We eliminate many costs by growing our own plants from seed, making composts and sowing mediums, growing summer and autumn mulch and saving seeds. We also provide our own support stakes from trees grown on site for the crops.

What we Record - Outputs 

Crop Yields All produce is weighed directly after harvest. The produce is recorded into two categories, fit for market and fit for processing.

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Financial output, Profit - The market value of the produce is estimated based on the average prices we were receiving from local buyers, veggie boxes and Trustika buyers club in Sofia.

N.B. We do not sell all of the produce from the garden. Some of the produce is consumed by the team or preserved.

What we record - Surveys 

Soil Analysis - Each spring and autumn we obtain a soil sample and send it to NAAS of the Ministry of Agriculture and Food. To take a sample we take approx. a hand trowel full of the top 20cm of soil from eight random areas from the beds, mix it together and send 400g 'bagged and tagged' to the lab the same day.

Physical Analysis - Each spring the team carry out a series of nine tests that are designed to provide an indication of soil health based on observable physical properties of the soil. It's a soil management tool developed by farmers for farmers to track the developing health of soils. We have slightly modified the test for our purposes.

Invertebrate Survey - Entomologist Chris Kirby-Lambert has been carrying out invertebrate surveys in the gardens for the last few years but unfortunately we did not have the funds available to complete this project. You can find his Outline of Invertebrate Diversity Monitoring Project here. We did start a new biodiversity study this year and I'll be posting our method and results from this survey in the coming weeks.

Pest and Disease - Thanks to Victoria Bezhitashvili, who joined us for the study in 2018, we have a general record of some of the common pests and diseases in the garden. You can find Victoria's observations here.

Results 

We'll start off by looking at the results from the soil analysis and soil health tests, then look at the results for each polyculture and finally finish up with the overall garden results.

Soil Results - Mineral Analysis 

Each spring and autumn we take soil samples and send them to NAAS of the Ministry of Agriculture and Food. The sample is taken before we add any fertility in March at the beginning of the season.

The first sample taken in March 2015 in the table below is the base sample taken before work in the garden began.


Sample Location - Aceaes
2019
Nitrogen mg/kg Phosphorous - Potassium mg/100g
April (before adding compost) pH (KCI) N03N NH4N P205 K20
6.8 29.4 20.2 59.9 26.4
2018
Nitrogen mg/kg Phosphorous - Potassium mg/100g
March (before adding compost) pH (KCI) N03N NH4N P205 K20
6.74 9.53 5.3 130 22
2017
Nitrogen mg/kg Phosphorous - Potassium mg/100g
March (before adding compost) pH (KCI) N03N NH4N P205 K20
6.73 25.1 4.85 147 39.6
2016
Nitrogen mg/kg Phosphorous - Potassium mg/100g
March (before adding compost) pH (KCI) N03N NH4N P205 K20
6.65 4.43 5.79 88 25.2
November (after final harvest) pH (KCI) N03N NH4N P205 K20
6.61 8.17 3.83 44.1 22.1
2015
March (before adding compost) pH (KCI) N03N NH4N P205 K20
5.69 15.4 2.89 16.3 13
November (after final harvest) pH (KCI) N03N NH4N P205 K20
6.44 16.2 4.45 43.9 14.4

Soil Results - Soil Health Card 

This year's soil health card test scored 72.2 - an increase from last year's test of 65.6. The highest score obtainable for this test is 88.

You can find the full results from 2015 - 2018 in the spreadsheet 2019 Annual Polyculture Market Garden Study - Published Records - Sheet 6.Soil Test Cards

Should you wish to use this soil card, you can download the Soil Health Card forms with instructions on how to carry out the tests here.

Inputs and Outputs - Zeno 

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The amount of time spent on Zeno was 46 hrs:


Task Time in mins
Set up 404
Planting /Sowing 327
Garden Care 585
Irrigation 105
Harvesting 300
Propagation 151.5
Fertility 12
Mowing 270
Market Prep 600
Analysis 5
Total hrs 46 hrs 
The fertility inputs on Zeno were as follows:


Fertility Inputs
Item
Total Quantity
Strawbales 31
Compost for
Tomatoes (L)
32.6 L
Seedling Mix
for Squash (L)
10.4 L
Seedling mix for Beans (L) 13.2 L
Wood Ash kg 6.72 kg
Mulch - Lawn Mower Clipping (L) 540 L
The yield outputs for Zeno totalled 198kg of produce - 3.59kg per m2.
Crop Weight in g
Tomatoes 20640
Tomatoes - (Processing) 1770
Beans 33140
Courgette 42425
Tomato (projected)
Basil 995
Total 197.94kg

Inputs and Outputs - Zeno Control

The amount of time spent on Zeno Control was 42 hrs and 50 mins.
Task Time in mins
Set up 378
Planting /Sowing 231
Garden Care 520
Irrigation 105
Harvesting 300
Propagation 151.5
Fertility 12
Mowing 270
Market Prep 600
Analysis 5
Total hrs 42 hrs 50 mins 
The fertility inputs on Zeno control were as follows:


Fertility Inputs
Item
Total Quantity
Strawbales 31
Compost s (L) 32.6 L
Seedling Mix
for Squash (L)
10.4 L
Seedling mix for Beans (L) 13.2 L
Wood Ash kg 6.72kg
Mulch - Lawn Mower Clipping (L) 540 L


The yield outputs for Zeno totalled 168kg of produce - 3.04kg per m2.



Crop Weight in g
Tomatoes 11895
Tomatoes - (Processing) 2450
Beans 23770
Courgette 41880
Tomato (projected)
Basil 3895
Total 167.78kg

Zeno Polyculture vs the Control 

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This year's results show the polyculture outperforming the control in yield by approx 24kg and taking approx. 7 hrs and 30 minutes longer to manage.


This year's results 


Zeno Control
Total time 46 hrs 42 hrs 50 min
Total Produce 197.94kg 167.78kg 



Last year's results 


Zeno Control
Total time 36 hrs 5 min 35 hrs 20 min
Total Produce 237.23kg 191.57kg 
You can find the above results in the spreadsheet 2019 Annual Polyculture Market Garden Study - Published Records - Sheet 9. Inputs and Outputs per Trial. For date stamped harvest records for Zeno see here.

Inputs and Outputs -  All Beds 

 
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Aponia - The Polyculture Market Garden

The amount of time spent in total was 88 hrs 50 mins:


Category Total time
Fertility 24
Analysis 10
Set up 782
Market Prep 1200
Mowing 540
Planting /Sowing 558
Garden Care 1105
Irrigation 210
Harvesting 600
Propagation 303
Total time spent 5332 min


Category Description

  • Garden Care - includes weeding, tying and pinching out tomatoes, replacing weak plants, inspecting plants 
  • Propagation - includes sowing seeds, watering seedlings, pricking out seedlings 
  • Market Prep - includes packing produce for market 
  • Harvesting - picking produce from garden 
  • Irrigation - applying water to crops after transplanting and during the high summer 
  • Mowing - Mowing the pathways and applying the trimmings to the surface of the bed 
  • Planting - Planting crops into beds and sowing crops directly into the bed 
  • Fertility - Applying additives (in this case wood ash)to the soil following soil analysis results
  • Set up - Preparing beds , forking over , mulching, adding compost, erecting supports and removing supports


The total fertility inputs for all beds:


Fertility Inputs
Item
Total Quantity
Straw Bales 62
Compost (L) 65.2 L
Seedling Mix
for Squash (L)
20.8 L
Seedling mix for Beans (L) 26.4 L
Wood Ash kg 13.44kg
Mulch - Lawn Mower Clipping (L) 1080 L

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Results in Summary  

The garden produced 365kg of produce from a cultivated area of 110m2.

The time spent on the garden was 88hrs from sowing the first seeds indoors in February to packing up in late October.

The fertility inputs of the garden were 63 straw bales, 1205 L of compost, 20kg of wood ash, 224 L of sowing medium, 1620 L of lawn clippings.

Comments on Results  

Time Input  

  • Not included in the records were other tasks carried out around the site such as making compost, harvesting stakes and support sticks, establishing beneficial habitat such as wildlife ponds, hedgerows/stick piles. 
  • The time for preparing the produce for market i.e quality control, packaging and delivery, was estimated at two hrs per week. 
Financial Inputs - Costs 
  • Not included here are the set up costs for the garden. These costs were included in the first years results. The costs recorded here are the annual operating costs which is basically the cost of seed, and fuel,oil and maintenance for the lawn mower.
Financial Output - Income 
  • A polyculture market garden should have a polyculture of revenue. Our study currently focuses on annual vegetable production. We chose to begin our study of annual vegetables as it is the most accessible practice to most people requiring the least amount of investment making it ideal for a novice or curious grower. Next year we begin to look closer at perennial polycultures trails in our new gardens. You can find out more about these trials here.
Other potential revenue from the Polyculture Market Garden includes perennial crops, plant nursery, adding value to produce and courses and training. We plan to add a record of these activities to represent better the financial potential of a Polyculture Market Garden.

Considerations
  • We aim to grow equal numbers of the same cultivar in the polyculture and the control but this year our courgette and tomato cultivars were not distributed equally. 
  • Due to the warm autumn and lack of frost Tomato - Solanum lycopersicum 'Currant Sweet Pea' that we planted last year made an appearance in the autumn with a nice crop of fruits from 5-6 plants that had self sown. The yield from these are not included in the records 
N.B. We took base times for the majority of tasks carried out in the gardens in the first two years of the study. These tasks were carried out by a volunteer team that had little or no prior experience in horticulture. An experienced grower or with repeated experience of these cultivation methods should be able to reduce the task times significantly.

This is an adapted article from the Balkan Ecology Project blog. For the full article, visit: https://balkanecologyproject.blogspot.com/2019/11/the-polyculture-market-garden-study.html

Useful links

Healthy food production and biodiversity

Video: How to grow an edible, annual polyculture

The polyculture market garden study - year 4 results at Balkan Ecology Project

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