Stop believing the lies, and stop repeating them…our soil is not “bad” and it’s not impossible to grow anything.
If our soil was truly “bad” then how did the Native Americans farm here for centuries before we came along? (You can read more about the Hohokam canal systems in the Salt River Valley here: https://www.usbr.gov/lc/phoenix/AZ100/1899/firstfarmers.html)
I want to do away with this rumor and, in the process, help you be able to grow more things, easier.
Our soil here in the Phoenix area is actually full of minerals and nutrients, enough to grow and support many different plants, when managed correctly. Many of our clay-based desert soils have a relatively high CEC (cation exchange capacity), while sandy patches in the Valley do not. (University of Arizona Soil Quick Guide on soil texture and nutrient-holding capacity: https://extension.arizona.edu/publication/soil-quick-guide) This means clay soils can hold onto a lot of those nutrients, rather than having them wash away. The problem: it’s chemically locked up. This means that all those nutrients are sitting there in the soil, but they can’t be used by plants.
Additionally, clay soil can hold onto water a lot longer than other soil types. Consider sand (on the other side of the spectrum as clay) that doesn’t hold onto water at all, it just flows right through. (See UA Extension’s discussion on soil texture and water-holding capacity: https://extension.arizona.edu/publication/soil-quick-guide)
What this tells us is that our soil is NOT “bad” or devoid of nutrients, rather it’s devoid of organic matter and biology. If we can add organic matter and biology, we can unlock more of those nutrients. If we can unlock more of those nutrients, then suddenly growing becomes much, much easier.
First, let’s talk about what it means to say the minerals and nutrients are chemically locked up. In the Phoenix area, our soil is very alkaline, which means the pH is very high. (University of Arizona on alkaline desert soils and nutrient availability: https://extension.arizona.edu/publication/understanding-nutrient-dynamics-desert-soil) When the pH is high, the nutrients are not able to be solubilized or absorbed into water and then be taken up by plant roots. This means you can throw down as much fertilizer as you want, but if the pH is too high, not much will be taken up by the plants. Instead, you’ll just leave behind a salt buildup that can be washed away into our water supply (and then pollute it). Salt buildup will also slowly kill your plants. Imagine throwing down tons of synthetic fertilizer and having it actually kill your plants!
Phosphorus is another example of this. In calcareous soils (like Phoenix has), phosphorus will bind or attach to calcium and magnesium. Once it binds, it becomes less available to plants and can be slow to release. (UA Extension explanation of phosphorus behavior in calcareous soils: https://extension.arizona.edu/publication/caliche-quick-guide) So throw down all the phosphorus you want, and a large portion may not be used by your plants.
Here’s the real culprits:
Compaction/poor aggregation. Water, roots and oxygen have a tough time penetrating our desert soils. (USDA NRCS overview of soil structure and aggregation: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health/role-of-organic-matter)
Caliche layers. We all know about caliche and the difficulty this presents when trying to dig and plant things. (UA Extension Caliche Quick Guide: https://extension.arizona.edu/publication/caliche-quick-guide)
Salts. We live in the basin of the Salt River. Our soil and water contains salts. Our irrigation water contains dissolved salts, and without proper management those salts can accumulate in the root zone. (University of Arizona discussion of salinity in desert soils: https://extension.arizona.edu/publication/understanding-nutrient-dynamics-desert-soil) (and yes, synthetic fertilizers contribute to salt buildup)
So we know what’s going on and what the real problems actually are, but how do we combat these things?
Add organic matter. Often less than 1% organic matter is typical in desert soils. (UA Soil Quick Guide reference: https://extension.arizona.edu/publication/soil-quick-guide) Because it’s hot and arid, most organic matter will quickly break down. In some areas, there’s a point where you can add too much organic matter. Here in the desert, it’s much more practical to increase organic matter than in many other climates. Organic matter is anything that was living. So start throwing down all your leaves, grass clippings, tree branches, pine needles, wood chips and anything else that comes from plants and trees. No need to compost it beforehand. Many are familiar with the term “chop and drop,” which means just trim your plants and allow everything to fall back to the ground. You’ll be amazed at how quickly these things break down and begin feeding the soil (or rather the biology in your soil). (USDA NRCS on the role of organic matter: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health/role-of-organic-matter)
Keep soil protected/covered. Exposed soil heats up dramatically and can reduce biological activity. The sun will absolutely bake and harm biology if left barren. It also dries out much faster. Covered soil is happy soil. You can cover with organic matter as mentioned above, or cover with a living ground cover.
Water correctly. As we mentioned above, our soil is full of salt. Plants don’t like salt. As salt builds up, we have to water more and nutrients become unavailable. Deep, thorough irrigation encourages deeper roots. Deeper roots improve soil structure over time. Water itself doesn’t magically aerate, but deeper roots and better soil structure from proper irrigation promote improved aeration and reduced compaction. It’s not just about quantity of water—it’s about how you apply it. (UA Extension irrigation and salinity guidance: https://extension.arizona.edu/publication/understanding-nutrient-dynamics-desert-soil)
Add biology. Quality compost, worm castings, and other soil amendments help bring the soil to life. Now that you are adding organic matter to the soil, the biology has food to eat. This means they’ll grow and multiply, which improves nutrient cycling and helps with soil structure. (USDA NRCS soil biology overview: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soil/soil-health/soil-health-assessment)
What happens when we do this?
The root-zone environment becomes more favorable for nutrient availability. The root zone environment becomes healthier, which helps plants access nutrients more readily.
Biology plays a central role in nutrient cycling and influences nutrient availability in the root zone. The bacteria, fungi, protozoa, and other soil life contribute to nutrient cycling and help with nutrient availability. (NRCS soil biology overview: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soil/soil-health/soil-health-assessment)
Mycorrhizal fungi. In a healthy soil, mycorrhizal fungi can help plants access water and nutrients beyond the immediate root zone and contribute to a more connected underground system. (USDA overview of mycorrhizal associations: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soil/soil-health/soil-biology)
A few important points about nutrients to keep in mind
Total vs. available nutrients. Soil tests often show nutrients present in large quantities. The issue isn’t total supply — it’s the fraction that is soluble and accessible to roots at any given time. Organic matter and biology help shift more of those nutrients into the available pool, but availability is what plants actually absorb. (UA soil testing guide: https://extension.arizona.edu/sites/default/files/2024-08/az1412.pdf)
The truth about soil tests. They’re useful for understanding what’s there, but they don’t tell you everything about how the soil behaves in the root zone. Use them as a guide, not a guarantee.
Buffering by calcium carbonate. Arizona soils are heavily buffered by calcium carbonate, which makes large-scale pH change difficult. (UA Extension Caliche Quick Guide: https://extension.arizona.edu/publication/caliche-quick-guide) That’s why improving the root-zone environment with biology and organic matter is so important—it helps you make the most of what the soil already provides.
What this means in practice:
Don’t panic about “bad soil.” Focus on structure and organic matter first.
Manage salts through irrigation so they don’t accumulate in the root zone.
Don’t chase fertilizer numbers blindly. Look at what the root zone actually needs.
Improve the root zone, not just the surface. Healthy roots unlock the soil’s potential.
Time matters. Desert soil improvement is gradual. These changes don’t happen overnight, but soil responds remarkably well to consistent inputs and smart management.
So yes, our soil is not “bad.” It’s capable, layered, and responsive to careful management. It’s about feeding the soil biology, protecting and feeding the soil with organic matter, and choosing irrigation approaches that move salts away from the root zone. It’s about understanding the difference between total nutrients and what’s actually available to our plants, and about recognizing texture, buffering, and the real constraints we face. When you work with the soil—adding life, providing the right environment for roots to grow deep, and managing salts and pH with patience—you’ll find growing here is not just possible, it’s practical and rewarding.
It’s time to stop accepting the myth and start growing with confidence.