Polyculture Trial — Apple Polyculture vs Monoculture — How Do they Compare in Terms of Costs, Soil Health, Biodiversity, Production and Time?

I’m so looking forward to the spring to meet our Polyculture Study crew and get back into the gardens. This season we’ll be shifting our focus to perennial polyculture experiments and forest garden yields.

During the last few weeks, I’ve been working on a new perennial polyculture trial that we’re aiming to start this April. It’s a long term comparative study looking at the input and outputs of growing an Apple tree in polyculture vs monoculture.

Thank you Simon Leupi for your feedback and suggestions on the study design, and to Chris Mallorie for discussing the trial with me, and working on the organic fertility and pesticide protocol.

Polyculture vs Monoculture Study

During this post, I’ll present the trial garden and trial design, cover what we will record, and take a look at some of the shortcomings of the study.

So, let’s start with a look at the garden where we’ll be growing the trials.

Trial Garden Overview

Location: Shipka, Bulgaria, Southeast Europe

Köppen Climate Classification — Dfc borderline Cfb

USDA Hardiness Zone: 5b (conservative) — 7a (risky)

Latitude: 42°

Elevation: 565 m

Average Annual Rainfall: 610 mm

Prevailing Wind: NW & NE

Garden Area — 352m2

Garden Location on our Project Map — See here

We’ll be growing four trials on the plot as seen in the below image. We chose this plot as each trial will more or less experience equal environmental conditions. There is a very mild slope on the site from N — S and no slope W-E.

Perennial Polyculture Research Garden — Orexis

The plant we chose to feature in the trial is Apple — Malus pumila ‘Red Cap’

Here’s some info on this cultivar

  • Origin: A mutation of a spur Red Delicious with a sweet taste and a crisp texture.
  • Growth: Strong growth, develops more shoots in comparison with other spur mutants of Red Delicious.
  • Fruit Colour: Ripens with a full deep dark red colour.
  • Fruit Size: Big, elongated fruits.
  • Fruit Storage: Good, similar to other clones of Red Delicious.
  • Taste: The fruit is sweet, with crunchy and firm flesh, which becomes softer during long storage.
  • Flowering: Early to midseason bloom. It blooms relatively early, but for a long period. Good pollinator cultivars include Evereste, Idared and Golden Delicious.
  • Production: Early and regular, at the end of September and beginning of October.

We’ve selected feathered whips (generally bigger than a whip with well-developed side branches) 2nd year on the graft with Rootstock — MM106. The selected plants will be of equal shoot and root mass.

The Four Trials

We’ll be growing 4 trials with each trial planted in a 56m2 area. The trials will include 2 polycultures and 2 monocultures as shown below.

Polyculture 1 — Suitable for broadscale application- Apple planted with two Nitrogen fixing shrubs (Elaeagnus umbellata) and bulbs at the base of the tree. The spacing of the shrubs and bulbs is such that a compact utility tractor can operate within the orchard, leaving two strips of wildflowers between tree and shrub rows.

You can find an example of how this polyculture would look within an orchard setting in the below image.

Polyculture 2 — Intensive polyculture. only really practical for gardens or small market gardens, schools, parks or small scale landscaping in general. It will be high maintenance.

Monoculture Organic — Apple cultivation with the full works of organic synthesized proprietary products applied (all recommended fertilizers, herbicides, pesticides and fungicides).

Monoculture Conventional — Apple cultivation with the full works of non-organic synthesized proprietary products applied (all recommended fertilizers, herbicides, pesticides and fungicides).

You can find the species list on our blog here

What we will Record

What we will record Soil Physical Analysis — Three Soil physical tests will be taken every 3 years in the locations seen in the below image, and should be rotated so that they are taken in a different quarter of the area every 3 years.

What we will record — Annual soil mineral analysis — Each year soil samples within each plot will be collected and sent off to the lab to test for N-P-K-Mg-Ca and soil organic matter.

Our project mission is to develop and promote practices that can produce food and other resources for humans while enhancing biodiversity, so it’s important to us to record biodiversity within the trials. We’ll attempt to do this via simple botanical and invertebrate surveys.

What we will record Botany — On the first week of each month during April — September, we’ll photograph all flowering vegetation within each trial plot, identify species and record on sheets.

What we will record Invertebrates — In the 2nd week of May — July, and September we will carry out 2 surveys (Thur & Fri) . The surveys will consist of’;

  • Sweep netting — 10 mins — Ground/grass layer
  • Vegetation Beating — 10 mins — Tree/shrub and herb layer
  • 4 Pitfall traps set on Thursday and emptied on Friday.

The number of unique species identified will be recorded for each plot.

What we will recordBiomass — All arisings from mowing will be weighed and recorded for each trial. For the two polyculture trials, we’ll also record the biomass trimmed from the E.umbellata shrubs that will be cut annually and kept trimmed to 1 m width and 1.5 m height. All trimmings will be weighed fresh and recorded on site.

The below image indicates (in greenish grey) the area of each plot that will be mown.

What we will Record — Growth and Development — The development during the year will be recorded using the BBCH Scale I.

Growth will be recorded by the girth of stem at the base and new growth at end of the season, the no. of flowers in the spring, and the weight of the fruits in the autumn.

What we will Record — Management — Polyculture 1 and 2 — Time and Cost to Manage each Trial

Fertility — Apply 20 L of compost to the surface of the planting area every spring for 4 years.

Mulching — Apply a thick mulch (10–20 cm deep) when the ground is thoroughly soaked and before the dry season begins for 4–5 years.

Irrigation — Applying approx 20 L of water every 20 days without rain (or when the soil is dry below the surface).

Weed/Mow — Mow area every 4th week of the month April — September.

Pruning — Formative prune when young i.e pruning to form the desired shape of the mature tree. Standard prune every year, i.e remove deadwood and crossover branches.

What we will Record — Management — Organic and Conventional — Time and Cost to Manage each Trial

Fertility — Application of recommended fertility additives.
Spraying — Application of recommended organic pesticide, fungicide, and herbicide additives.

Irrigation — Applying approx 20 L of water every 20 days without rain (or when the soil is dry below the surface).

Weed/Mow — Mow area every 4th week of the month April — September.

Pruning — Formative prune when young i.e pruning to form the desired shape of the mature tree. Standard Prune every year i.e remove deadwood and crossover branches.

What we will Record — Time and Cost to Establish each Plot

Plant, Materials and Labour costs will be recorded for each trial.

You can find a slideshow of this trial design here.

Shortcomings of the Study

We are practicing amateur science and have no formal training or education regarding the design of such trials. Any feedback regarding the design of the trial is very welcome. We are planning to start the trial in April 2020 so we have time to make amendments. Please do get in touch if you have something to add or take away.

Some of the shortcomings we’ve identified so far include:

Replicates of each of the trials would be great, but we are currently limited by suitable space. It would be great to find other people in similar biomes to run the trial simultaneously.

Proximity to wild areas will impact the invertebrate measurement of the organic and conventional plots and will not be representative of a typical monoculture environment.

If you are in a position to carry out this trail in sync. with us, or know someone who may be, please get in touch. It will be great to have the trials running in different locations simultaneously and to compare the results. We’re still working on the final protocols, but when we’re ready we’ll be happy to share our protocols and record-keeping sheets to anyone that may be interested.

If you would like to be involved in our trial and projects we’re working on, we still have a few 4 week and 2-week positions available during June — July — August or September on our Polyculture Study this year. If you would like to join us you can find out more and register here.

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We look forward to hearing from you.

Upcoming Forest Garden Courses

If you would like to learn how to create a forest garden and gain some practical hands-on experience come and join us for our Design and Build a Forest Garden Course. We’ll be covering site surveying, landscape design software, installing access, beds, irrigation channels, planting tree, shrub, herb and ground layers, and wildlife ponds. All in 3 days! And plenty of follow up material to take away with you to digest slowly.

Design and Build — Forest Garden Course — Regenerative Landscape Design Course

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Regenerative Landscape Design Online Course

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