During this post we will be looking at various ways to prepare beds for planting, specifically for planting trees and shrubs. I'll introduce you to a trial we started this spring where we're looking at 5 different bed preparation methods to see which method works best. We'll go through how to implement each method, why they are useful and finally look at the criteria we are judging the effectiveness of each method by. We'll start with an introduction to the trial garden where we are undertaking this comparative study.
In April 2017 we began the development of our new trial garden (Ataraxia). The garden will be used for a range of perennial polyculture trials and experiments in order to discover the best practices to produce nutritious affordable food while enhancing biodiversity.
When planting trees and shrubs into grassland or fields previously used for agriculture, I prefer to prepare the area at least 6 months ahead of planting, 12 months is even better. We often prepare the planting zones in early spring for late Autumn planting. I call this "advance planting preparation".
Advance Planting Preparations - (APP)
The benefits for advance planting preparations include the following:
Wood chip - The smaller diameter the source wood is, and the more green material in the chip, the faster it will decompose. Chip from small diameter source wood is called ramial wood chip and is the best material to use for mulch in APP. Photo credit David Domoney
An excellent green manure - Sainfoin - Onobrychis viciifolia
- You need to apply large quantities of mulch and manures and for large areas this will often mean importing from offsite. If you can tap into local waste streams (as mentioned above) this is fine but it some places it can be expensive to purchase and transport these materials.
- Plants that grow via rhizomes and runners such as brambles and couch grass may grow through or around the sheet mulches and green manure cover. This can be overcome by removing these plants before mulching, or spot weeding as they reappear. If the area is dominated by pernicious weeds it's probably best to take the time of removing them before mulching.
- On heavy clay (especially compacted clay) applying organic matter to the surface (mulching) is not very effective as the clay layer forms a barrier or "pan" that is restrictive to the plant roots and the organic matter is not easily naturally incorporated into the clay. In these cases it's necessary to incorporate the organic matter into the soil via double digging or deep ploughing the area, adding the organic matter and then rotary tilling. The initial work is intensive but following this applying organic matter to the surface will work (so long as the area is not compacted again).
- On any compacted soils it's worth breaking the compaction and relieving any pan that may be present before mulching.
- It's necessary to prepare a seed bed when using green manures and this often entails ploughing and tilling the area for large areas or digging over and raking for small areas.
- Always apply a mulch following periods of heavy rain or water the area well beforehand to ensure the soil is well soaked. This will activate the microbiology in the soil that play a critical role in the decomposition process.
Setting up the Beds
Digging out the shrubs and saplings from the area and piling the material on the perimeter of the area.
Beds pegged out and defined with string. The mini digger in the background is digging out the pond at the highest point of the site.
Our five methods for advance planting preparations
1. Inverted Sod and Mulch - (Soil - Straw)
2. Green Manure - (Plough - Till - Sow White Clover - Sainfoin and Marigolds)
3. Dig over and Sheet Mulch - (Card - Manure - Straw)
4. Sheet Mulch - (Card - Manure - Straw)
5. Straw Mulch (Straw)
All of these methods are best implemented when the soil is moist, for example, following heavy rains when the soil profile is thoroughly soaked but has had enough time to drain i.e not water logged.
1. Inverted Sod
Method one entails slashing the existing vegetation to ground level and leaving it on the surface. A layer of inverted sod is then applied to cover the surface of the bed. In some cases you may wish to dig out the top soil from the pathways and this can be inverted on to the bed area. In this case we wished to leave the pathways grassed and used top soil removed from a pond excavation on site. Following the top soil a layer of straw mulch is applied approx 10-20cm deep.
Inverted Sod applied to surface. This is followed by a layer of straw.
2. Green Manure
Method two removes the existing vegetation and replaces it with plants that can improve the soil for the incoming plants. For example on sites with low fertility soils, nitrogen fixing green manures are a great way to lift Nitrogen (N) to appropriate levels. The green manures can also add significant quantities of organic matter to the soil improving structure and drainage and can serve the needs of beneficial insects.
To boost the organic matter content of the soils, the green manure should be cut at regular intervals and plowed into the soil or covered with a straw mulch before planting occurs. In such cases the green manure used should be a fast growing annual cover. An alternative is to sow a perennial cover, cut back at regular intervals (once established) and plant the crops directly into the living mulch.
We sowed the following seeds onto the prepared bed on the 18th May.
Trifolium repens - White Clover 200g - Perennial
Tagetes patula 100g - Annual
Onobrychis viciifolia - Sainfoin 100g - Perennial
We'll probably need to irrigate this bed from July onward for a good cover to establish and we'll cut the vegetation in late summer and decide whether to mulch before planting in the Autumn or plant directly into the mulch based on the performance of the cover.
To prepare for sowing we ploughed and rotary tilled the area to provide a good seed bed.
We then hand sowed the seed onto the surface before a rainy period was forecast.
The use of cover crops to prepare beds for perennial polycultures is something we'll be experimenting more with in the future.
3. Fork Over and Sheet Mulch
Digging over the bed, placing a layer of card and cloth, adding 30L of manure and covering with 15-20 cm layer of straw.
4. Sheet Mulch - Cardboard layer, manure layer, straw layer
5. Straw Bales
Placing bales on the planting locations of the trees clears the weeds from the planting zone, encourages a fungal population of soil microbes and within 6 - 12 months the surface of the bale at ground level will decompose providing a light layer of compost for the newly planted tree/shrub.
How we are measuring the effectiveness of each method
The criteria we are judging the effectiveness of the methods and how we will measure effectiveness is as follows:
- The smallest amount of effort for the greatest benefit i.e in labour, materials. - Record of Inputs
- The least expensive method (without sacrificing quality) - Cost Analysis
- The least disturbance to the existing ecosystem - Entomology Survey
- Mineral analysis compared to base sample - Mineral Analysis
- Physical analysis compared to base sample - Soil Test Card
- The beds should provide great soil conditions for the incoming plants i.e, free from competitive neighboring plants, good structure, moist and fertile, free draining. - Observational Report
Will be publishing the results of our trials in the winter.
What will we be planting in the beds
Overview of Bed Plantings and APP Methods used for each bed
For the full post, visit: https://balkanecologyproject.blogspot.co.uk/2017/06/5-ways-to-prepare-beds-for-tree-and.html
Watch: How trees talk to each other