How to Prepare Soil for Food Production: Using Soil Testing, Amendments, Cover Crops

I want to share insight and the timeline of a project I am working for a client which will ultimately become an area for apple tree guilds. In future posts, I will showcase the design, and explain the power of using plant guilds, but before that I will describe the process, and steps I have taken to prepare the soil for future food production.

Soil Testing

After determining the site where the apple tree guild will go in the future, the first thing I did was test the current soil to discover the starting condition. This required two separate type of tests; One soil test was for type of soil makeup (sand, silt, clay) and the other for essential nutrients and Ph levels. To test the soil makeup you can do the following:

1. Take a quart sized mason jar and filled it with soil halfway

o Dig at least 6 inches deep and use soil from multiple areas of your desired planting region

2. Fill it with water so it is around three quarters of the way full

3. Add a teaspoon of dish soap

4. Shake vigorously for several minutes and then let it set for several hours until it completely settles (best to leave it overnight)

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After this process, you will begin to see different layers of the soil components. The sand will sink to the bottom, the silt in the middle, and the clay will be on top. The ideal percentage 40% sand, 40% silt, and 20% clay. I discovered the soil composition I was working with was heavier in percentage with clay than desired so this needed be addressed when amending the soil.

The second set of tests I performed where to test the Ph levels, and the Nitrogen, Phosphorus, and Potassium levels also know as NPK levels. For this test I used Rapitest by Lusterleaf which you can buy on Amazon. I also used the Sonkir Ph/light/moisture sensor to test the soil as well. I will post the links at below if you desire to use them.

After these tests I discovered, the Ph, Potassium, and Phosphorus levels were in ideal ranges, but the Nitrogen levels were close to depleted. This data is helpful to target what I need to plant and focus on to prepare the soil for plant and food production in the future. I would need to focus on nitrogen fixing plants. Once all of these tests were done, now began the hands on work to begin restoring and regenerating the soil to help both the environment and increase the soil fertility to produce sustainable and resilient food.

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Soil Amending

The client had previous evergreen trees in this selected area that needed to be taken out. Then we needed to remove the large roots and the clusters of roots left from the Podocarpus. I dug throughout the selected area around 18 inches deep, to make sure when the apple trees go the soil is prepared well and there is room and space for these new trees to be rooted well and thrive. After going through section by section and removing all the roots, I began to backfill the worked through soil in layers.

It was during this time I began to add two key soil amendments to improve the clay soil. Gypsum was used to improve soil drainage to make sure the water went deep into the ground to reach the roots of the future fruit trees and surrounding plants. Expanded Shale was added to help increase water absorption to provide adequate water supply to the roots and water retention to conserve to extend is availability for use and decrease irrigation costs.

To do this effectively I alternated between gypsum, soil, shale, soil and repeated this process until most of the soil was backfilled. You can hand sprinkle each of these amendments in, it doesn’t have to be a thick layer. Try to spread it evenly, approximately one handful per square foot. You can apply the gypsum throughout the whole back filling process to aid water drainage throughout the soil, but focus your Expanded Shale amended only for the first half to two thirds of the backfilling process. This will ensure the water retention is primarily where the deep roots will be.

Once I completed this backfilling process, I spread 2-3 inches of garden soil on top; I used Kellogs All Natural Garden Soil from Home Depot (link below). I used 8 bags of this which was to cover the ground, 1 bag (3cu ft) for every 15 sqft. At the end of the article I have posted a link for a good calculator to see how many bags of garden soil you use are needed.

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Summer and Winter Cover Crops

After accomplishing this in the summer time, I planted two comfrey plants to help with nitrogen and create a living mulch that will be used before the apple trees and also once the apple trees are planted as well. Comfrey will be part of the future design of the apple tree guilds. The annual cover crop I planted to help fix the nitrogen levels was the cowpea, commonly known as the California black eyed pea. These legumes will fix nitrogen with its roots deeper in the soil, and when you cut them down before they flower, the cuttings are then left on top to decompose and add nitrogen to the topsoil as well. After about two to two and a half months I cut back the cowpea, and broke down some of the comfrey growth to add to the soil fertility and fix the nitrogen levels during the fall.

The 2-3inches of Garden Soil, Comfrey, and Summer Cover Crop Cut back and left to decompose and restore the Nitrogen levels

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When winter was beginning, it was time for the winter cover crop to continue to replenish the nitrogen levels before planting the apple tree guilds this spring. I used hairy vetch, a good winter annual cover crop that can tolerate frost. Right now this is coming in well here, and with the amount of rain we have had here in California along with cooler temperatures, even mushrooms have grown in the soil. These are good signs of healthy fungal and bacteria in the soil which will aid in the tree and plant vitality in the future; as the weather warms, the mushrooms should die back but the decomposition will be beneficial in the soil matter.

I will use the same approach of cutting winter cover crop, hairy vetch, before it flowers and leave the cuttings to decompose with more comfrey leaves will restore the nitrogen and add good organic matter to the soil. I plan to do this several weeks before planting the apple trees and the surrounding plant guilds to maximize the soil fertility, giving the new apple trees and surrounding plants the best ability to be rooted and receive the essential nutrients for plant growth.

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Hairy Vetch Winter Cover Crop Growing Until Early Spring

Actions you can take to Prepare your Soil

‍Overall, testing the soil and amending it with the right nutrients and organic matter through soil amendments and cover cropping are important to prepare healthy soil that can support optimal plant growth. If you want to prepare your soil for growing food, there are a few key actions to take based on this article:

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1. Test your soil. Get a soil test kit to determine the nutrient levels, pH, and soil composition. This will tell you what amendments you need to make.

2. Add amendments. Based on your test results, add amendments like gypsum, expanded shale, and compost or garden soil to improve the structure and nutrient levels.

3. Plant cover crops and plants that will accumulate dynamic nutrients to help in composting. Sow nitrogen-fixing cover crops like cowpeas, vetch, and comfrey to replenish nitrogen and add organic matter as they decompose.

4. Repeat the process. Test your soil again after amending it and growing cover crops. Repeat and adjust as needed until your soil is in good condition for planting your fruits and vegetables.

5. Start small and build up. Don't try to amend and prepare your entire garden area at once. Focus on a small section first to test your soil preparation methods, then expand outwards over time.

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With patience and the right soil preparation techniques, you can transform your garden soil into a nutrient-rich environment that will reward you with bountiful, healthy harvests for years to come. I hope these tips help get you started on the path to productive, living soil!

These practices and steps enable nature to perform and produce as designed. If you want to learn more, make sure you subscribe to this blog for future projects and insights. If you'd like a permaculture and regenerative agriculture consultation, please contact me by clicking on and filling out the Regenerative Agriculture contact form.

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Be blessed and may your harvest be plentiful!

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