Soil. Arguably, one of, if not the most important factors of market farming.

Think about it, if your soil sucks, so will your vegetables. If your soil is thriving and full of the necessary elements, your veggies will be delicious and nutrient-dense.

That’s what you’re going for, right?

Before you start farming, it’s important to get a soil test done on your land so you know what nutrients are present and which components need to be added in by way of soil amendments.

Five Amendments For Building Soil

To build fertile soil, five amendments should be applied as raw materials. 

Organic Matter

This is generally a mixture of compost and manure. When mineralized by organisms in the soil, it makes nitrogen, phosphorus, sulfur, and several micronutrients readily available to plants.

Any organic matter not mineralized builds up in the soil and contributes to its structure.

How do you add organic matter to the soil?

Once you know how much organic matter is present in the soil (from your soil test), you can manage the organic matter in a couple of different ways.

1. Build your soil by adding a large initial organic matter amendment to obtain a high level of organic matter in your garden. Adding Peat moss is a good way to do this.

2. Maintain soil fertility by making up for lost organic matter due to mineralization, tillage, erosion, and plant uptake.

This is achieved by using compost, green manures, and crop residues in your beds.


Phosphorous is required for root development in young veggie plants and plays a key role in the formation and maturation of fruits and tubers.

Phosphorus is mineralized from organic matter, so all practices that increase biological activity in the soil also increases phosphorus availability to the plants.

Regular applications of compost and manure should provide the soil with enough phosphorus to meet the needs of your veggies.

An additional way to meet your plant’s phosphorus requirements is to apply rock phosphate, a natural rock powder, every four years.


Potassium plays a role in allowing root veg to keep for long periods and has a positive effect on the size, colour, and taste of fruit veggies.

It also makes plants more vigorous and resistant to diseases, parasites, and adverse weather. 

Unlike nitrogen and phosphorus, potassium is NOT mineralized from organic matter. It is present in most soils in its mineral form, mostly in the clay fraction.

Most veg crops require a lot of potassium, so it is fortunate that the natural fertility of most soils, coupled with crop rotation practices, along with regular additions of compost and manure will be sufficient to meet the needs of most market farmers.

Calcium, Magnesium, and Sulfur – Secondary Nutrients

These secondary nutrients play an important role in vegetable growth and are components in healthy soil.

Limestone rock is a ground rock containing calcium and magnesium that is used to raise the amounts of these nutrients, as well as the soil pH.

Sufficient lime should be applied to keep the pH within the range of 6.2-6.8. 


Also known as trace elements, are essential for crop growth, just in tiny amounts. 

Generally speaking, the existing levels of micronutrients in the soil, good crop rotation, and regular additions of compost should be enough to ward off micronutrient deficiencies in your crops.

That being said, if your soil is depleted in one or more micronutrients, Greenspan Marl (glauconite) may be what you need. It is an ancient seabed deposit considered a broad spectrum source of micronutrients, applied every 4 years.

Dried seaweed is also a popular source of micronutrients, it breaks down more rapidly and has the additional benefit of stimulating biological activity in many soils.

Importance of Good Compost

Good compost can supply both the organic matter for soil building and the fertilizer for the crops. It is packed with soil organisms that activate biological activity in the soil.

Compost is created from the decompositions of carbonaceous organic detritus (straw, leaves, animal bedding, etc.) mixed with nitrogenous material (manure, crop residues, etc.) through a process in which different organisms work on reorganizing this organic matter.

When the mix is composed of different ingredients at the right proportions and when decomposition occurs in optimal conditions, the result is a rich and stable amendment containing almost all the elements needed to grow veggies. 

As straight-forward a concept of compost is, it is not all that easy to make yourself.

Note: Raw manure is not a substitute for compost, you need the other ingredients as well.

The composting process is as follows:

1. Compost stabilizes nitrogen and produces an amendment that releases nutrients gradually over the growing season, even over multiple years.

2. Kills potentially pathogenic agents but more importantly the weed seeds that lurk in animal manure.

Importing weeds into a garden is a costly mistake that is paid back with extra weeding for many seasons. We don’t want that, do we?

3. Creates active soil life (fungi, bacteria, earthworms, etc.) which gets transferred to the garden and colonizes it. This added microbial life competes with disease-causing microbes and helps maintain healthy plants.

4. Eliminates clumps, resulting in a light, homogeneous soil that is easy to shovel and spread over the garden.

soil infographic

Homemade Or Commercial Compost?

Depends. Do you have experience making compost? Do you have the time to devote to monitoring and turning your compost pile regularly?

If you answered yes to these questions, go ahead and start your own compost pile, sounds like you got things under control.

Answer no (like me) to one or both questions? Maybe look into buying your compost instead of making it yourself.

This may go against all that you stand for but buying compost from someone who knows what they are doing can result in higher quality compost than what you would have made yourself.

Specialized compost companies have the proper equipment and methods needed to intervene at critical stages of the decomposition process. They will constantly monitor temperature and humidity and turn the pile at the right time.

The result of this expertise is a well-structured homogeneous compost mix that comes with a minimum N-P-K (nitrogen, phosphorus, potassium) soil analysis.

In the end, the extra expense of commercial compost is worth it for the quality of veg it produces. 

We plan on using commercial compost for the first few years at least. Maybe forever, who knows! Sometimes, it’s just best to leave things to the experts.

Bottom Line

Soil fertility is of the utmost importance to a market farmer and should be considered very carefully.

This is not the area where you want to skimp or cut corners. The veggies you grow depend on the fertile soil they are growing in to become delicious, nutritious foods. 

This article is only a snippet of what you need to know about soil fertility. Please do your own research and ask organic farmers in your area about their compost routines. 

Much of the information in this article is from Eliot Coleman in The New Organic Grower, as well as J.M. Fortier’s the market gardener. Also, check out more must-read books here.

Do you use your own compost or commercial compost for your market farm? Let us know in the comments below.

Stay Local,

Kathy & Jon

your friendly neighbourhood growers


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