Climate Resilience through Home-Grown Soil Fertility

Each month, we share expert-led training sessions to help community orchard stewards grow and care for thriving fruit trees. On this page, you’ll find a recorded workshop, a summary of key takeaways, and additional resources to deepen your knowledge. Be sure to explore past workshops for even more insights into urban orcharding best practices!

Interested in attending a workshop? Sign up for our workshop series email list!

Overview:

Impact of Climate Stress
CoreConcepts: Soil Tests, Minerals, Mycorrhizae
Practical Steps:
- Mulch, mulch, mulch
- Add organic matter
- Cover crops
- Tree guilds
Rootstocks & varieties
Holistic sprays & additional ingredients

Indigenous Acknowledgements

Many of the practices below emerge from indigenous peoples with a deep connection, stewardship, and respect for the land. It is a core principle of land stewardship for us to take care of what has been given to us by Mother Nature.

Increased Climate Stress

Various factors of climate stress cause more challenges in community orchards:

Increased Heat/Cold Cycles bring more stress, more insect life cycles
Increased and Variable Precipitation - higher fungal diseases
Stronger winds and storms cause more damage to trees, opening up wounds for diseases to take hold
increase in the chance of late frosts, swings in temperatures during the wintertime bring about early blossoms that are prone to frost damage

Soil Food Web

Soil is made up of a complex web of fungi, bacteria, and animals. These organisms in the soil break down organic matter to make nutrients accessible to plants.

The soil food web is the way the forest creates nutrients from organic matter; fungi, bacteria, and microorganisms work together to decompose organic matter into available [?????]
Nutrients are not directly available to plants without help from the soil food web!

Soil Tests

Getting a soil test at least once a year allows you to understand what is happening in your soil and allows you to avoid being blind to what is happening underground

Take soil samples from multiple locations, at least 4-6 inches deep (refer to these Soil Test Instructions)
For fruit trees, make sure your soil test includes the following items:
- pH: Aim for a pH level of 6.3 - 6.7 pH (Too acidic/basic soil makes nutrients unavailable)
- Macronutrients (Nitrogen, Phosphorus, Potassium, Calcium, etc.)
- Trace Mineral Levels
- Heavy Metals

Ideal pH Ranges for Fruit, Vegetables, & Blueberries, credit: Susan Poizner

Law of the Minimum & The Importance of Minerals

TRACE MINERALS: iron (Fe), manganese (Mn), boron (B), molybdenum (Mo), copper (Cu), zinc (Zn) and chlorine (Cl).

The law of the minimum is a core idea in agriculture & medicine is used to understand growth of plants
This means that whatever element you’re missing has the most effect, even with “trace minerals” at the very smallest amounts
For example, boron plays an important role in the formation of flower and fruit development
Organic & holistic methods will not work well without attention to trace mineral levels!
The pace at which plants convert amino acids into proteins is directly related to availability of trace minerals
Sources for Minerals: Azomite, Rock Dusts, Sea-90, homemade plant extracts of Stinging Nettles, Dandelion, Comfrey

Mycorrhizae- Create the Conditions for Thriving

Mycorrhizae are the root systems of the mushroom fruiting body

They work together with a plant’s roots to expand root uptake of nutrients and water by up to 100x
They break down woody materials, and through the soil food web, make nutrients accessible to the roots of the trees
Mycorrhizae have a symbiotic relationship with 85-90% of plant species; the trees provide sugars in exchange for other nutrients
“Bridge trees” (like willow, alders, cottonwood, poplar) allow for the exchange of minerals from bedrock to fruit trees
Support mycorrhizae by providing a food source: Lignins - proteins in wood, found in highest concentrations in small diameter branches less than
Ramial wood chips are wood chips made from small diameter branches less than 3-4 inches thick, that contain high amounts of lignins to feed mycorrhizae
Use the Technique of Hugelkultur (burying various sizes of hardwoods under soil) to act as a long-term food source for trees
On a small scale, you are burying carbon and making an impact toward mitigating carbon emissions

Hugelkultur

Method of burying various types and sizes of woody debris (branches and logs) and organic matter under topsoil; as organic matter breaks down, it provides nutrients for trees and plants in future seasons

Hugelkultur beds can be above ground, half-dug into the ground, or completely buried to be level with the ground
Can be used in community orchard settings as small piles of branches, buried under compost or topsoil

Mulch

Mulch helps to retain moisture for the trees, keeps weeds down, and supports mycorrhizal growth

Trees cannot access nutrients in the soil without moisture; stress from drought can also trigger insects to feed on trees (insects can hear the cracking of dry bark)
Apply a 2-4 inch thick layer of mulch under the canopy of the tree in a donut shape
Keep at least 6 inches away from the trunk. Do not pile mulch up against the tree, as it can cause the tree to die or break at the graft union
Use a diversity of mulch sources: put different materials in new places each time to increase the diversity of your soil food web
Organic matter, like composted animal manure, feeds the soil food web and provides a source for nutrients accessible to trees
If possible, allow larger wood chips to break down for a year before placing them under trees
Sources of mulch include: wood chips, composted animal manures, decomposed leaf mulch, rotted straw or mulch hay (be cautious with hay, as it can contain weed seeds)
When possible, use ramial wood chips, made from small diameter branches (under 3-4 inches) of hardwood trees, to give mycorrhizae lignin-heavy food sources
If heavy metals are present in soil, mulch covers them, lessens surface exposure, and dilutes their presence in the soil
Avoid dyed mulches as they can disrupt the soil food web

Organic Matter

Organic matter management is one of the best ways to increase soil fertility over time

Ideal rates of organic matter are above 3% (minimum) up to around 6% organic matter; above 6% can start to have too high nutrients or moisture, leading to fungal disease and other problems
Sources of organic matter include: wood chips, leaf mulch, composted manures, cover crops,
Every 1% Increase in organic matter yields a potential 12% increase in harvest production
ChipDrop can help connect to a local source for wood chips: https://getchipdrop.com/

Cover Crops (aka “Green Manure”)

Cover crops are plants grown in place to improve soil quality and structure, add organic matter, accumulate nutrients, and minerals

Exact decision of crop type will depend upon your horticultural zone, and what time of the year you are planting
Various purposes for cover crops: Nitrogen Fixer, Organic Matter, Nutrient Accumulation, Soil Erosion, Improve Compacted Soil, Suppress Weeds
NorthEast Cover Crop Council has Cover Crop Decision Tool to help match soil goals to [?????]

Rootstocks & Varieties: Tree Choices

Choosing disease-resistant tree types and fruiting varieties is one of the best ways to prevent future disease infections

Use the Giving Grove Recommended Varieties as a reference
Certain cultivars are more susceptible to specific diseases; heirloom varieties are less likely to have resistance
Choose cultivars with successful track records for the most common disease and pest challenges in your area (i.e., fire blight, scab, fungal diseases)
Native fruiting varieties like Paw Paws, Serviceberries, and Persimmons often require less maintenance than grafted cultivars of Peaches, Apples & Pears

Tree Guilds

Tree guilds are a technique of permaculture that uses companion plants paired with fruit trees that benefit soil quality, pollinator habitat, and repel insects

Plants are planted close to trees, under the canopy, but not too close to the trunk
Plants are generally categorized into the following groups (some are in more than one group):

Nitrogen Fixers/Dynamic Accumulators - Plants that build soil fertility
Repellants - Strongly scented plants to repel pests
Ground Cover - Plants that keep the soil covered and moist
Pollinator Habitat - Establishes homes for beneficial insects
Edibles & Medicinals

Common plants included in tree guilds include: comfrey, chives, garlic, daffodils, yarrow, echinacea, clovers, bee balm, oregano, thyme

Holistic Sprays

4 Core Spring Holistic Sprays & 1 in Fall: Neem/Karanja Oil, EM, Kelp, Liquid Fish

The aim is to improve nutrient availability, suppress pests and disease, and increase the diversity of microorganisms in the soil
Sprays are a two-way street! Sprays also feed into the root system and soil food web
Additional Spray Ingredients: Kaolin Clay, Biofungicides (Regalia, Serenade), bT