Since I started gardening I have considered myself green thumbed. I have had no trouble making plants grow and keeping them alive, mostly. But it turns out that plants are pretty keen on being alive, and with the right conditions plus a little attention they will manage to make it through. Having plants that thrive or vegetables that taste good and last once harvested… now that takes some skill and some know how.
When you talk to life long farmers about what they do to produce quality crops it doesn’t take long to see that it is second nature to them. They can tell what the soil needs just by looking at the leaves on plants. Like anything this kind of confident, tacit knowledge takes a lifetime of experience to foster.
A good place to start is understanding that if your soil is healthy your plants will be too. Some methods of ensuring healthy soil are: following a crop rotation, adding compost regularly and fertilizer occasionally, alternating between cover crops and production crops and reducing compaction. This may seem like a lot, but it all happens as part of one big system and the rewards are huge – I mean prize winning pumpkin huge.
Crop rotation is one of the most important steps to creating a sustainable growing system. It prevents build ups of plant specific pests that live in the soil, like potato bugs, and it helps to prevent depletion of soil nutrients. The basic idea is that you should not be planting the same family is the same plot year after after. The most common practice is to leave at least three years between plantings of the same family. There are many different ways to plan a crop rotation and benefits to each. I will write a detailed blog post about my personal experiences and what works here on the farm. You can also find a quick breakdown and example rotation schedule here.
As plants grow they pull up nutrients and water from the soil. Some of those nutrients and a lot of that water makes it into the parts of the plant that we harvest and eat or sell. This means that we are running a nutrient deficit. If we were to continually plant vegetables in the same soil and take the fruit away to be consumed eventually the soil would become infertile. In order to preserve soil health we have to close the loop and return nutrients to the soil. When harvesting we don’t usually take the entire plant to be consumed, there is often leftover plant material. This should either be tilled back into the soil or gathered and added to a compost pile. If you are not producing enough organic matter to create a decent amount of compost you can also purchase it locally. Adding fertilizer at a few times over the season will also help to maintain soil nutrients and aid in plant growth. Homestead organics will test your soil and provide you with a custom fertilization plan. They will also work from an existing soil test, or help you to choose what amendments will work best for your soil.
If you have enough space to rest your soil and plant it in cover crop it can pay in dividends. The cover crop itself will act as a weed suppressant, meaning less weed management for you, it will also provide you with green manure when you till it in. The plants you select to use as cover have different benefits. For example legumes help to fix nitrogen in the soil while buckwheat suppresses weeds and attracts pollinators. OMFRA provides helpful profiles of the most common cover crops.
Soil compaction is the biggest reason for crop failure. It means that plants have to work extra hard to get their roots deep into the soil and it means that the soil is not a nice environment for soil microorganisms. If plants cannot form health root systems they will not be able to gather the nutrients necessary to grow big, strong and tasty. See the diagram below for a couple examples of soil compaction.
The beet furthest to the left is growing in an area with nice soil structure. You can see that there are varying sizes of soil aggregates, allowing water to drain through the soil, roots to grow deep and providing a nice home for soil microorganisms. To maintain healthy soil structure you should follow the directions above and minimizing tilling.
The center beet is growing in similar soil but in an area that has been repeatedly tilled and plowed. You can see that a hard shelf of compacted soil has formed a few inches below the soil surface. This is also referred to as hardpan, it will prevent roots from going deep into the soil – leading to smaller vegetables and it will cause water saturation in the top layer of soil – causing root rot. To prevent hardpan use implements that go deeper into the soil – like a spader, avoid walking on beds, consider permanent beds and allow cover crops to grow long enough or their root systems to penetrate the hard soil.
The furthest right beet is in highly compacted soil, maybe a dense clay. This is a pretty growing situation and can take years to improve. Vegetables will struggle to grow in the tight unyielding soil, moisture will sit on the soil surface and it will take a long time to dry out. It is very difficult to alter the soil structure in large areas but you can try mixing in sand, lots of organic matter, and tilling in lots of green manure.