compost-southwest-soil

Soil Loves Compost – Especially in the Southwest

The title is a bit misleading. It’s not the soil that loves the compost – it’s all the plants that grow in the soil! And not just plants! There are countless life forms – mostly microscopic – that live in the soil and further help plants.  They love compost too.

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Southwestern plants, like this queens wreath, love soil with ample rich compost in it.

Why? What’s so special about compost?

Compost is part of the natural process of building better soil for plants to grow in. Mother Nature does not sweep her floors! All those leaf bits and dead flowers fall to the ground, decay, and provide nutrients and acidic components for plant that dropped them to keep on growing. Another word for decay is decompose – creating compost!

A Bit of Science

Southwestern soils are virtually all alkaline. On a pH scale, Southwest soils are generally 7.7 to 8.5 pH. Most plants will grow better in mildly acidic to very mildly alkaline soils with 6.0 to 7.5 pH. Yes, even cacti. This is one reason they often grow tucked in under other plants.

Don’t believe me that your soil is alkaline? Go find a bit of bare soil in your yard and pour some nice acidic cider vinegar on it (pH generally 5.0). The acid vinegar will bubble and fizz like acidic vinegar and alkaline baking soda do.

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The white layer in this soil is caliche – a rock-like layer that needs acidic compost to help break it down so roots can grow.

How to Compost in the Southwest

You can purchase compost in bags at the nursery. It’s a quick way to get started. You can also very easily compost at home. However, many HOAs (Home Owners Associations) forbid it because if improperly cared for, composting can be troublesome. Hint – you can compost in five-gallon buckets in your garage, with no-one the wiser.

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Dark, rich compost. Good for our soil!

Compost Ingredients Are Different in the Southwest!

Here in the arid Southwest there are three components to successfully creating lovely compost – green, brown, and blue. (In humid climates they skip the blue component.)

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Somewhat photogenic “green” kitchen waste.

Green Materials

This includes things like cucumber peels, citrus rinds, coffee grounds, tea bags, banana peels and vegetable kitchen scraps. Grass clippings are okay if they are non-invasive grass clippings. Avoid Bermudagrass in any form (grass clippings, hay, horse manure), it can take over your garden.

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Less than photogenic kitchen green waste one week later. This will smell and attract flies without a lid and some brown material.

Brown Materials

This is the carbon component, and includes dropped leaves like palo verde, pine needles, mulberry and the like. Brown is also a shovel full of soil from your yard. Your soil should have the micro-organisms that will do the compost work. Also – recycle your junk mail! A paper shredder helps make it smaller. Sawdust works too – just not from pressure treated wood.

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Bucket of green kitchen waste needs a layer of brown soil on top to help provide decay organisms.

Do the Blue!

Blue represents the water essential to keep it everything moist so the micro-organisms can break down the materials into something ready to go into the garden soil. Keep your compost enclosed and moist. If it dries out it will not decompose.

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Add water so the compost stays moist and can decompose! Photo courtesy of Dramm.

Avoid these in your compost!

Avoid animal products such as meat, dairy, bacon grease. In the Southwest – avoid eggshells. We already have excessive calcium in our soils, and don’t need any more.

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Compost demonstration area at the Tucson Botanical Gardens. Your local botanical garden may have something similar.


Go Forth and Compost

You will need an enclosed space. Open compost heaps and piles often fail in the Southwest. Our air lacks humidity and the materials quickly dry out and cease to decompose.

There are any number of compost bin options on the market, look for fully enclosed ones. If they have air vents, make sure the vents are screened to keep out insect pests. You can build your own bin with cinder blocks, or use five gallon buckets with lids, or for and entirely low-tech (and back-breaking) option, dig a hole in the ground and use that! Just keep it covered to prevent evaporation.

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Compost that wouldn’t! It kept drying out because it was too open. Enclosed bins work better in our climate.

Add green and brown components as if you were making a giant lasagna. Add ample moisture, and keep the pile “cooking” by turning the”lasagna” once a week. This helps mix the components and add necessary oxygen. Add more green and brown in equal portions at any time, and blue as needed. One month before you are going to harvest your compost, stop adding any new material.



soule-vegetables-southwestTo learn more about composting and using compost in our unique Southwestern region, consider this book: Southwest Fruit and Vegetable Gardening, written for Arizona, Nevada and New Mexico (Cool Springs Press). This link is to Amazon and if you buy the book there we may get a few pennies. Your favorite Amazon “Smile” charity will also benefit.

© Article copyright Jacqueline A. Soule. All rights reserved. You must ask permission to republish an entire blog post or article. You can use a short excerpt but you must give proper credit, plus you must include a link back to the original post on our site. No stealing photos.

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