Foundations of garden success

Soil Health in the Garden and Farm

If I were to choose one predictor of mankind's future, I'd pick soil organic matter (SOM). It is so essential, I consider building SOM to be my primary task as a gardener. When the soil is healthy and rich in SOM, gardening gets so much easier. There's better moisture retention, steady nutrient supply and less pest pressure.

Here in the desert, SOM can be very hard to find and build due to lack of water, high temperatures and thin soils. Higher amounts of SOM soak up and hold more water and release it over time, a precious gift in the heat of summer. What's more, abundant SOM feeds the living organisms in the soil, the hardworking livestock of successful growing.

Assessing and building soil health are where I think all growers should start.

Building soil health

What is Soil Health?

Take a minute to think about what healthy soils are. What do they smell like, look like or feel like? On some, instinctive level, we know healthy soil when we see it. For one, healthier soils are darker than other soils and have a pleasant, earthy smell.

Soil health is measurable too though. Growers should have a general idea what type of soil they have in order to make good decisions. Is the soil high in clay or sandy? How fast does water infiltrate? How easy is it to push a stake in?

Soil Health Assessment

Soil can be assessed by the beginner, using some simple tools & procedures. Understanding the soil can help the gardener know how to make good management decisions about watering and soil health.

The soil texture can be felt by squeezing and making "worms" with the moistened soil. Sand is the largest type of particle and makes soil worms fall apart and feel gritty when rubbed between the fingers. I have sandy soil which drains water quickly. When soil worms bend without breaking, there is likely more clay in the soil, smallest of soil particles. Clay binds together tightly, slowing water movement and binding nutrients.

Knowing the soil texture should help you know how to set up watering systems. But it's important to know how fast water actually infiltrates. This can be done by digging a hole in the ground, filling it with water and then timing how long it takes to drain.

Though more common in clay soils, my concreted sands also infiltrate water very slowly in new beds. With double digging and other practices I follow, the soil becomes much less compacted over time. I do not step on my garden beds without good reason.

For measuring soil organic matter, soil tests can provide more accuracy though. I recommend an initial soil test and a yearly repeat, or as often as needed. It can be costly, especially if you have one of the good tests with bio-assessment, but they can reveal key mineral deficiencies and the impact of your practices over time. I have the goal of retesting my soil this year.

the New Food Garden

There are 5 Soil Health Principals that will help growers improve their existing soil:

Maximize Presence of Living Roots
Minimize Disturbance
Maximize Soil Cover
Maximize Biodiversity
Incorporate Animal Impact

Maximize Presence of Living Roots

Living roots leak a steady stream of sugars and nutrients to the soil community. This improves fertility, creates good structure and protects soil. Using living cover crops in the winter is an example of living roots. Use of grasses and clovers for paths keeps the unwanted weeds and mud in check. Biointensive growing allows beds to be quickly replanted with new crops to minimize bare ground conditions.

Minimize Disturbance

Disturbed soils tend to lose organic matter, structure and beneficial soil microbes. Tillage, pesticide application and even fertilizing are examples of disturbances that make soil less resilient and more vulnerable. No-till, organic farming methods are a good example of minimizing disturbance. Avoid stepping on prepared beds to keep from compacting the soil.

Fungi and mycorhyzae are the heavy lifters in soil health. Their strands grow slowly, winding through the soil, offering nutrients to plants and weaving together soil aggregates. Disturbances like tillage and compaction really do a number on fungi, damaging tender strands and cutting off the important services they provide the soil.

Maximize Soil Cover

Bare soil is open to erosion, higher temperatures and loss of nutrients. Covering soil with mulches or living plants will reduce evaporation and hold soil in place. Leaving the plant stubble in beds after harvest can reduce work and leave cover in place.

The UV radiation, the wind and the dryness in my area are brutal on uncovered soil. When I first assessed my soil coverage, it was barely 25% and I thought I'd been doing a good job. Today, between wood chip mulch, stepping stones and garden residues, I have around 80% coverage. This has slowed the wind erosion that was stealing my garden.

Maximize Biodiversity

Nature does not monocrop the way large, conventional farms do. To improve soil health, add different crops and rotate them, with pollinator beds all around. Biointensive growers generally have many small beds of different crops, and even 2-3 crops in the same bed. This mash-up confuses pests and feeds a variety of beneficial insects and soil organisms. They protect plants and soil exponentially through this diversity.

Incorporate Animal Impact

Animals play a critical role in all ecosystems and the garden is no different. Growers have many options for including animals. Manure can be added to the compost, pollinators lured in with flowers and chickens can be tractored around after harvest to clean up. By protecting insect habitat around the garden, natural pest predators can find welcome space and keep the garden protected.