As part of our working bee on Sunday 11th June, a Soil Health workshop was held by Richard Main. Richard is currently working with 'Gardens for Health' and part of his work involves 20 schools and over 60 community gardens.
In 1998 the Sanctuary garden began as an 'open laboratory' for Unitec. Richard was a tutor and Sarah Abbott was one of the original students he taught.
The Sanctuary gardens have some of the best soil in NZ and quite possibly the world. The soil is both enriched and bountiful, being light and friable which ensures that it never gets water-logged and therefore stays workable year round.
The primary function of soil is to provide plants with air, water, nutrients and a medium for growth and physical support. Soil is made up of;
45% Earth
25% Water
25% Air
5% Organic matter
with air being the most important ingredient.
To investigate the profile of (your own) soil, dig a hole. The layers in the soil may be evident and these layers are referred to as 'Horizons'.
The top layer is called the 'O horizon' - Organic matter
The second layer is called the 'A horizon' - Top soil layer
The third layer is called the 'B horizon' - Subsoil layer
Finally the 'Parent material horizon' - Rock and fragments
The soil from our sanctuary hole had;
7 cm of O-horizon
60 cm of A-horizon, being the top soil, which is very deep.
30 - 40 cm of B-horizon, that for us is clay.
Parent material for us is a rock base.
Soil health and improvement is about building up the microbial layer - the 'Micro-citizens'. These need to be valued. To see how many micro-citizens are in the soil, mold a 'sausage' of soil from the B-horizon layer. The 'mucus' exuded by the microbial population holds the soil together. Drop your 'sausage' to the ground and if it stays together, then this represents the presence of a good microbial population.
To build up microbes in the soil (to heal the soil) add compost. Organic material encourages microbes.
The soil bacteria, Mycobacterium vaccae, is also referred to as the 'happy bacteria' see;
https://qz.com/993258/dirt-has-a-microbiome-and-it-may-double-as-an-antidepressant/
M. vaccae can enter the body through the pores of the skin and through nicks and cuts = happiness!
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Additionally, soil needs to be rested. Avoid chemicals and artificial fertilizers as these can lead to sterile soil which is not good.
When Rudd Kleinpaste visited he was amazed by the diversity of insect life at the Sanctuary garden. The diversity here really exploded with the planting of host plants; trees, shrubs, perennials and annuals. Also, focus on planting flowers to promote insects.
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Recommended reading
1. The Soul of the Soil; A Soil-Building Guide for Master Gardeners and Farmers
2. Organic Gardening by Soil and Health Association Organics NZ
3. The one straw revolution by Masanobu Fukuoka
4. Gardening for planet earth by Dee Pigneguy
5. Zen Gardening by Veronica Ray
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Handout sheets follow;
Soil Profile Test
The primary functions of the soil is to provide plants with air, water,
nutrients and a medium for growth and physical support
Soil is made up of-
45%____________
25%____________
25%____________
5% ____________
earth water air organic matter
Practical -
Looking at soil gives us a picture of what soil health is like
Dig a spade depth down and wide.
View the soil profile ….the layers in the in the soil may be evident
.
O Horizon………Organic Matter ….top layer
A Horizon………Top Soil Layer….second layer
B Horizon…….Sub Soil Layer….third layer
Parent Material horizon……..rock and fragments
Practical Questions-
1 What soil horizons can you see?
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2 Measure the depth of O, A and B horizons
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Soil Score Card
1. Name Soil…………………………………………..
2. Date…………………………..
3. Is Soil…. sandy ( light)….. loamy ( between light and heavy) …..Clayey ( heavy)
4. Is Soil…. dry….slightly moist…wet
5. Is soil ….cold… warm …hot
6. Is soil made up of small …medium or ……large size clodes or segments
7. Name the number of colours in the soil_____________________________
8. How many worms and insects can you count in your soil ______________?
9. Are Micro-Citizen alive and active in the soil?
Micro-citizens are the key to soil health. Soil tests will offer an insight into soil condition only. Check for micro citizens by taking a handful of soil, moderately moist and squeeze it. If it sticks together this is a good indicator. If it sticks together when you drop it on to the ground it is REALLY GOOD.
What we are assessing is Mucus, the substance soil bacterium exude when they are Healthy. The fact that there’s enough to bind soil particles together indicated a substantial, healthy microbial mass.
Reference…… Sustainable Dream by John Pearce
All these answers help you decide if the soil is good to grow food and plants or does it need help from you.
10 We can improve soil condition with the addition of green crops herb leys , liquid brews, composting and organic fertilizers eg
Soil Improvement
Herb leys - for cropping over 6 months to 2 years Crop rotation.
Benefits
To replenish soil and attract beneficial insects and pollinators
living ground covers that helps to control and suppress weeds, retain moisture, prevent erosion and attract beneficial insects and bees. It acts as a nutrient fixer and recycler, looks gorgeous and saves labour.
lupin , clover, rye grass , prairie grass, wild flower mixes, chicory, phacelia, buckwheat, alfalfa, oats, mangle beet, sorrel, plantain, caraway, dill, and yarrow, cocksfoot, fescue, praire grass, poppy, chicory, fennel
Sowing Rates- 3-5 grams per 10m2 or 1kg per 150m2
Green manure and nitrogen fixing crops- 2-6 months
Benefits
improves soil fertility
When dug in, adds nutritious elements to your soil
Increases levels of beneficial fungi & bacteria
Broken down plant material adds humus (water holding component)
Prevents soil from drying out, can hold moisture longer
Breaks up/aerates soil allowing more microbes/insects in
Stops erosion by sun (panning/caking), wind (topsoil blown away) and rain (topsoil washed away)
Controls weeds by occupying spare space in your garden
Controls pests in the soil - for example nematodes
mustard, lupin, nasturtium, alyssum, beans, vetch, buckwheat, beans, peas, crimson, white and subterranium clover , soyabean
Sowing Rates- 1kg per 40m2 or 100 kg per acre
Carbon Mix- 3-6months
Benefits
Reduce carbon emissions through carbon capture in soil
Use conservation tillage and controlled traffic techniques in cropping operations.
Avoid burning crop residues and retain prunings and stubble where practical.
If cultivation is absolutely necessary, do not till excessively wet or dry soils.
Avoid periods of bare fallow. Ensure continuous plant cover where possible.
Manage irrigation and soil drainage to reduce waterlogging.
Rotate crops and include rotations of perennial pastures and legumes.
Add composted material where practical.
Manage soil structure to maximize plant uptake and minimize nitrogen loss (e.g. use gypsum on sodic soils).
Manage livestock waste (dung and urine) to minimise nitrous oxide emissions.
Manage soil nutrient levels by choosing nutrient targets, completing a nutrient budget to determine fertiliser requirements, match nutrients to the nitrogen input and hence maintain those targets.
Don’t overgraze pastures. Keep sufficient groundcover throughout the year.
Manage livestock movement/paddock rotations to reduce compaction/soil structure decline in overgrazed paddocks.
Livestock
Wheat, barley, oats, broad beans, peas, corn
Sowing Rates- 5 grams per 10m2 or 1kg per 150m2
Seed sources-
Mitre Ten stores
Newton Seeds online
Mon-Fri 8 - 4.30pm
, Sat 9-12pm
35 Angle Street, Onehunga, Auckland
PHONE: 09 6364918, FAX: 09 634 5916
EMAIL: john@newtonseed.co.nz
Happy Gardening.
