An Introduction to Soil in Albuquerque
An Introduction to Soil In Albuquerque
If you are planning a new landscape element in your yard, a garden, or maybe even starting a small farm, the first thing you must consider is the soil. Soil is the conglomerate of organic matter, sand, silt, clay, and rock that makes up the uppermost layer of earth where plants can grow. You can omit any one of these, except organic matter, and still have soil, but healthy soil is not pervasive, especially in the desert.
A healthy soil is a vibrant, life filled ecosystem that maintains itself in unison with the plants and bugs the live in it. Just a handful of healthy soil contains more microorganisms than there are people on the planet, but though this system is nearly contained, the more vegetation it supports, the more care it needs. In the high desert, more care means more organic matter.
Soil Makeup in the Albuquerque Area
The basic components of soil composition seem simple, but they all have an important task. Air and water make up between 40-60% of a healthy soil system, mineral (dirt) components make up ~45%, and organic material (decomposed organic matter) makes up the rest. The mineral composition of desert soils varies widely, but in Albuquerque the sand makeup is mostly granite, limestone and sandstone with all the minerals associated with those rocks (feldspar, quartz, potassium-feldspar) and of course, plenty of ash and basalt from the area volcanoes. In the Bosque the soils are a more diverse buildup of silt and clay as the Rio Grande filters and deposits in its ebbs and flows.
In order for organic matter to quickly decay into its beneficial elemental structure two basics must be in abundance: oxygen and water. The high altitude (low oxygen) and low moisture climate of New Mexico does not create an abundance of organic matter and as such our native soils offer very little nutrition for plants to thrive. Of course, this doesn’t hold true for all of New Mexico, or even all of Albuquerque, as certain areas of the region have their own microclimates with more favorable conditions, but the general makeup of soil in Albuquerque is sand and clay.
Sand, Silt, and Clay
Sand, silt and clay are essentially the same thing, eroded rock, classified by size. Each one plays an important role in the makeup of soil. Sand, the largest particle, helps with air flow and drainage so plants’ roots do not stay overly moist and develop mold and rot, but it cannot hold nutrients. Silt is porous, it allows water to flow and drain but not quickly, it holds nutrients but does not lock them in. Clay is the most dense. Clays’ small particle size allows the particulate to bond together like a puzzle and, like a puzzle when put together, forms a tense, impermeable surface allowing little to no drainage but can lock in and store nutrients. When these three blend together in equal parts they create loam, the perfect palette for plants to thrive.
In Albuquerque it is not uncommon to have large deposits of sand and silt covering thick, concrete tough deposits of caliche. Caliche is often referred to as clay, but it is actually a calcium carbonate that acts as a binding agent for sediment, essentially creating a cement out of clay particles. Building a garden on top of a caliche deposit is problematic, as water will collect on top of the caliche and potentially flood the root zone leading to root nutrient deficiency or root rot. Caliche can be removed but it is an astonishingly difficult process, or it can be broken down over time (sometimes a very long time) by the application of organic matter and a lot of TLC.
Photo by Lucie Hošová
Organic matter in soil is like DNA in living organisms, the building blocks from which new life can grow. There are many elements to the make-up of organic matter in soil – worms, bugs, microbes, and most importantly, decayed organic matter, what we call compost. When once living organics decay, they don’t break down into just nothing, they return to their elemental state in in the form of minerals and acids that can be consumed by new growth. Nitrogen, phosphorous, potassium, et. al. that are be found in soil are the result of decayed organic material. Without these elemental nutrients, plants have no food (counter to popular belief, it turns out plants need more than just water and sunlight) and cannot grow to their potential.
In New Mexico organic matter needs a little help breaking down. Ok, it needs a lot of help. The lack of oxygen in our high altitude combined with low moisture means that organic matter does not decay in a manner that creates the micro-biodiversity and elemental nutrition in the soil to promote vigorous plant growth. In lower elevation areas with high humidity, you will always see extremely diverse and robust plant growth. This isn’t simply because of moisture, but because the moisture allows for organic material to decay quickly into a rich soil that decays further into humus. In arid environments like the plains of New Mexico, the microbes that break down organic matter cannot naturally thrive, so plant matter cannot break down into compost and humus. This is why organic matter needs to be introduced and replenished into most soils in New Mexico for healthy plant growth.
Raw Manure vs Compost vs. Chemical Fertilizers
Albuquerque’s climate doesn’t allow for an abundance of natural organic matter to break down easily so organic material needs to be introduced in the form of manure or compost. In and around the Bosque, a fall application of raw manure might be all you need to revitalize the soil for a healthy spring and summer, but raw manure only provides nitrogen and carbon, more diverse nutrients will need to be applied for many crops. Many farmers with established fields use raw manure as they are working with established soils that already have microbial life that only need a bit of extra fuel and can quickly break down the manure – think of it as an espresso for the soil.
Compost, on the other hand, is made from manure, green waste such as yard clipping and leaves, and food waste and is collectively decomposed through management. Compost provides an abundant source of most nutrients’ plants will need. The diversity of organic matter that is decayed is important to increase the diversity of available nutrients and beneficial fungus and microbes. Compost is less like an espresso shot and more like a whole meal that provides foundational energy stores.
Many farmers and gardeners opt for chemical fertilizers to offset deficiencies in their soil, and these are always an option for quick results. Chemical fertilizers add nothing to the creation of healthy soils, but with a proper application and attentive care to individual plants or crops, chemical fertilizers can help you grow and maintain healthy plants. If you are looking to transform your soil from the sandy clay conglomerate into a healthy micro-ecosystem, chemical fertilizers will offer little to no help.
The Perfect Soil
The perfect soil does not exist, but healthy thriving soils can be found in every neighborhood around the world. Soil in Albuquerque is fickle, but with time and effort (and more time and effort in some cases) the desert soil can become rich and abundant with life. Whether you are a new gardener in Albuquerque, or experienced but wondering why your neighbors garden is doing so much better, understanding the soil is the most important aspect of getting your roots set and healthy.