Permaculture Projects

Green Manure Trials, Building a Micro-Wetland, Perennial Polycultures and Forest Garden Plants

Week 16 - The Polyculture Project

It’s been another hot week here in Shipka. We’ve taken to starting our work in the gardens at 7.30 am to avoid the heat and it’s working well with the fresh and cool mornings.

Tobi and Christina left the week before last back to Germany where they are working on a free range rabbit farm called Mobihasy, rearing rabbits and developing their own buildings and management systems for the operation. Good luck with your project guys and thanks for your help in the gardens.

So here’s what we’ve been up to in the gardens.

Green Manure Trials

Introduction – This spring we started a Green Manure/Cover Crop Trial,  a very simple 3 year comparative study where we sow 3 m2  patches of three different Nitrogen fixing ground covers

The species and quantity of seed used for each patch is as follows
Onobrychis viciifolia – Sainfoin – 55 g (husked seed)
The idea is to look at how fast each species takes to provide cover, how well each species prevents volunteer plants from establishing , the quantity of biomass produced and how attractive each patch is to invertebrate wildlife in the gardens.
The Trial  – The seed was sown in the first week of April. None of the patches were irrigated or weeded and the first cut is made in the second week of July with the second cut made in the last week of September. The July and September cuts will be repeated for the following 2 years.
The below photos were taken 7 days after sowing – The Onobrychis viciifolia – Sainfoin had not germinated. The Trifolium repens – White Clover  germination rates were highest and provided the most cover. Medicago sativa – Alfalfa/Lucerne germinated but at a lower rate than the clover.

In July we undertake 5 simple tests. Weather conditions on the day of the tests are recorded (see below)

  • Ground Cover – estimation of how much of the bare soil is covered in each patch
  • Volunteer Plant /Green Manure  Ratio – estimate of the % of volunteer plants there are to the green manure plants in each patch
  • Canopy Obs – 5 mins observations counting the number of unique invertebrate species seen within each patch
  • Ground Obs – 5 mins observations counting the number of unique invertebrate species seen within the 30 x 30 cm quadrant placed within each patch
  • Biomass Weight (g) – Cut all vegetation (green manure and volunteer plants) to ground level and record weight of biomass
The below photos are taken just before the July cut –  only a few Onobrychis viciifolia – Sainfoin plants established with the vast majority of vegetation you can see in the below photo being volunteer weeds. Trifolium repens – White Clover provided the most thorough cover growing approx. 20 cm high and a few volunteer plants can be found growing through the cover.  Medicago sativa – Alfalfa/Lucerne provided decent cover with more volunteer plants growing among the cover and had reached approx 50 cm tall.

Here are Christina, Tobi and Shahara taking 5 minute observations of  invertebrate life in the vegetation canopy and 5 minute observation of invertebrate activity in a 30 x 30 cm quadrant.Lea is on the right keeping records. The number of unique species are counted. We do not identify the species nor do we count the number of the same species within each patch.
This isolated observation test is not very useful and in the future we will undertake the obs tests everyday for 2 weeks prior to cutting and average the data to getting a better impression of invertebrate diversity within each patch.
Here are some common invertebrates from the gardens.
We cut down the vegetation to just above ground level with a machete and scythe and weighed the total biomass (including volunteer plants). The cuttings were used to mulch the annual vegetable beds nearby.  Here is Tobi cutting the Alfalfa biomass to ground level with the machete.
The Results 
Weather Conditions
Date – 16/07/19
Time – 11.30 a.m
Temp – 22° C
Weather – Bright and Sunny
Other – Ground well soaked from recent rainfall
A – Trifolium repens – White Clover
Year 1
1st Cut – 16.07.19
Ground Cover 95%
Volunteer Plant /Green Manure Ratio 20%
Canopy Obs 13
Ground Obs 9
Biomass Weight (g) 4225
B – Onobrychis viciifolia – Sainfoin
Ground Cover 70%
Volunteer Plant /Green Manure Ratio 98%
Canopy Obs 8
Ground Obs 10
Biomass Weight (g) 3585
C – Medicago sativa – Alfalfa/Lucerne
Ground Cover 80%
Volunteer Plant /Green Manure Ratio 30%
Canopy Obs 14
Ground Obs 10
Biomass Weight (g) 2985


The results from the first set of tests showed clearly that Trifolium repens – White Clover produced the most biomass and provided the best cover. Very few Onobrychis viciifolia – Sainfoin seeds germinated. This could be because we used husked seed or perhaps the seed was not sown deep enough. The Onobrychis viciifolia – Sainfoin patch was 98% volunteer plants so this plot provided a good example of how the wild vegetation compared to the two other species. It’s worth noting that in terms of biomass weight the wild volunteer plants provided more than the Alfalfa but not as high as the White Clover.

1 week after the cut both  Trifolium repens – White Clover and  Medicago sativa – Alfalfa/Lucerne are recovering well. We will repeat the tests again in the last week of September.



Aponia – The Market Garden

Every year I intend to grow more Melothria scabra – Cucamelon . They are easy to grow from seed and provide delicious refreshing little fruits during the hot months of summer. This year Lily built a frame for the plants and they seem to be establishing well with the first fruits appearing last week.

We have started to bring the water diverted from a mountain stream into the pathways in the veggie garden. The pathways serve as irrigation channels and the water soaks into the raised beds. We’ll leave the water running through the garden overnight.


Beetroots under the shade of Paulownia tomentosa – Foxglove Tree doing well


Ekpyrosis – Forest Garden

We’ve been putting the finishing touches on our new forest garden the last few weeks including the addition of a small wetland area that sits in the middle of the productive beds as seen in the below illustration of the garden. The main purpose of this garden is to grow Vaccinium corymbosum cv. – Blueberry and Rubus idaeus cv. – Raspberry  while the wetland should provide habitat support for wildlife such as dragon flies, frogs and hoverfly larvae that should help control pests in the garden.

We dug out an area approx. 1.2 m wide and 5m long and 25 cm deep , cleared all of the sharp stones from the pit and lined this with  tri-laminate LDPE liner, an off cut from some pond liner we used in a pond a few years back. You can find more about using pond liners and pond building in our previous blog posts here
We filled the liner with a layer of pebbles and river sand and inserted four cylinders  approx 25 cm high and 50 cm diameter into the fill. The cylinders were made from cutting a plastic barrel into 4 pieces. The purpose of the cylinders is to provide some areas for free standing water for animals and birds to drink from and frogs to lay spawn. We propagated a number of marginal/emergent aquatic plants from our wildlife ponds and planted these directly into the sand.(you can see the species used in the above illustration of the garden. Finally we placed rocks around the edges and some larger rocks in the sand and these should provide good basking areas for reptiles. The Micro-wetland seems to be working okay so far, although we do need to adjust the sides as water is flowing onto the pathway in places. I’m looking forward to watching the aquatic plants develop and some wildlife move in overtime :)
We’ve also added two more beds to the garden, here is Lea and Shahara digging the channel for the next section of beds. First we peg out where the channel path and beds will go, than we broad fork the bed area, dig the water channel placing the soil on the beds area, add compost and mulch heavily with straw. We need to make a few adjustments in the height of the channels and then the garden is ready for spring planting.

Forest Garden Plants

Vitex agnus-castus – Chaste Tree in flower. This deciduous shrub is native to the arid and semi arid Mediterranean and Western Asia, and widely cultivated in the warm temperate regions and subtropics. This beautiful plant has a thousand year old history as a pharmaceutical drug, is used to make dyes and provides strong material for basket weaving. The blooms prolong into the autumn and are great nectar providers for honey production and have earned the plant a place in ornamental gardens worldwide..

A wild Prunus cerasifera – Cherry Plum growing in the field behind our market garden. I’ll be writing about the wild polyculture of plants growing around this tree next week. This tree is one of the better tasting wild plums in the area and it’s packed full of fruit this year.
It’s a bumper crop year from plums. Prunus insititia- Damson and  Prunus cerasifera – Cherry Plum
I’ve been growing the productive polyculture photographed below in the home garden for the last 9 years. Composed of Zanthoxylum piperitum – Japanese Pepper Tree to the south, nitrogen fixing Spartium junceum – Broom  in the centre and Vitis vinifera cv. – Grape  cultivars planted around the outside that climb the Broom.  Below the trees and shrubs is a mixture of herbs including  Allium schoenoprasum – ChivesFoeniculum vulgare – Fennel Hypericum perforatum – St Johns WortLavandula angustifolia – Lavender , Melissa officinalis – Lemon balm , Mentha × piperita – Peppermint  Origanum vulgare – Pot MarjoramSalvia officinalis – Sage  and  Symphytum grandiflorum – Dwarf Comfrey ground cover. The polyculture provides a regular supply of herbs, a good harvest of grapes and plenty of the wonderful spice Sichuan pepper. It’s extremely attractive to wildlife and I’ve not added any compost to the area for at least 7 years so appears to be well fertilised by the chop and drop pruning of the nitrogen fixing  Spartium junceum – Broom and other plants.


Paul Alfrey

Hi I'm Paul, Originally from the UK I moved over to Bulgaria with my family 12 years ago and set up the Balkan Ecology Project. Prior to that, I worked as a freelance Arborist in the UK for 15 years. Balkan Ecology Project is a family project run by myself, Sophie and our two boys Dylan and Archie, and supported by the amazing volunteers we have hosted here over the years. We aim to develop and promote practices that provide nutritious affordable food while enhancing biodiversity and work to achieve this by: - Researching, designing and implementing systems on the ground - Providing working examples of our designs at our sites open for the public to visit - Providing quality education and training to aspiring growers and landscapers - Providing consultancy and design for landowners and farmers across Europe - Practicing an open source policy, whereby we disseminate our results freely and share all aspects of our work - Growing, selling and promoting the use of plants and plant communities that have high ecological and nutritional value Our activities currently include: Biological Plant Nursery, Educational Courses, Local Land Stewardship, Polyculture Research, Market Gardening​, and Consultancy and Design.

One Comment

  1. Hello Paul

    I have a question about your cover crop study. Why did you set up the experiment in the manner you did? In other words, why is it important for you to find out, on a single species basis, which of those three sprouted better and had more biomass? I am not understanding the goals you have for planting the cover crops in the first place, if this is the only information you want to study.

    My understanding is that the main reason for planting cover crops in any permaculture design context is to boost soil fertility and improve the soil structure. Both, as I understand it, are best done with polycultures (not monocultures) of cover crops since a polyculture above ground will create a diverse ecosystem (soil food web) in the soil that will be much more likely to sustain anything else you decide to plant in the area. Natural succession in soils, however, is never achieved with monoculture, since nature does not do things this way. How about including a plot with different combinations of those same plants in your experiment? Plants are definitely going to function differently as monocultures than in combination with other species, as well, so I´m curious about the way the experiment is set up….

    In your study, the careful separation of plant types is distinctly a reductionist manner of experimenting by setting up simplified test goals (fastest sprouting; most bio-mass) and comparisons between plants with careful control of context (inasmuch as one can in nature). If you have decided to plant a monoculture cover crop, this experiment may have some value, but that idea itself seems out of place in a permaculture design….. It may be that you DO want to sow a monoculture cover crop, however, and I am curious about why you would want to do that.

    Thanks a million for sharing your work with us!
    Linda Morrison

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