Varieties and Properties of Arizona Soil
Tillage can make or break crop growth and yield. Knowing the soil and tillage
techniques is paramount when trying to have the most bountiful and sustainable
harvest possible.
Conservation tilling is the best way to manage the soil dynamic in the Arizona area.
Since so much of Arizona soil contains large percentages of sand and clay loam, it is
difficult to keep organic content and water in the soil. Using No till, strip till, or
single pass techniques, there is less of a chance of erosion and a decrease in organic
material.
No till holds the most organic content but runs the risk of runoff and is difficult to
weed. Using this method in alfisol, aridsol, and inceptisol soil you will have higher
organic matter levels but a difficult time managing the fields.
Single Tillage or one pass tillage will be beneficial for any soil type because it keeps
at least 30 percent or more organic material in the soil and eliminates weeds. Before
tilling be sure to decide on driven paths and tilled areas. This will keep most of the
soil nutrient-rich while sacrificing a small part of the fields.
Only tilling areas plants will be growing is strip tillage. It avoids large amounts of
land and nutrients from being exposed to the harsh, drying sun but it does decrease
the organic material on the surface. This can be useful in mollisol and entisol soil
because it prevents erosion and the soil still contains organic content.
Maricopa County has a variety of each type of soil. Though they mostly have clay,
silt, and sand loam in their soil, it is still available for agricultural use. Irrigation is
often necessary when there is clay, silt and sand in the soil. By irrigating, the water
saturates the soil, making it more pure for plants and easier to maintain in the drier
months. Conservation tillage has also helped keep organic content and moisture in
the soil. With single pass, no till, and strip tillage, crops have been able to thrive in
harsh conditions. Crops like rice and lettuce thrive in this soil.
The county also wants to protect as much of their rural land as possible. Some land
in the county is under agricultural exemption. To protect farmlands, Arizona has
decided any mining, railroad, grazing, and agricultural land can be exempt from the
regulations put forth by the Zoning Ordinance and the Building Safety Ordinance.
This means it cannot be considered for residential or commercial construction
unless the certificate is lifted. By doing so, the land will never be threatened with
residential or commercial development and will remain farmland. This secures
Arizona local agriculture and part of their economy.
Maricopa County has cooperative extensions with the University of Arizona. These
cooperatives are used to promote knowledge of Arizona’s agricultural growth and
maintaining Arizona soil responsibly. Classes, externships, and events have helped
keep Maricopa County and Pinal County environments sustainable and safe.
Knowing the soil and how to till the land is essential when trying to grow on a largescale farm in Arizona. Because the soil can be drastically different due to
environment or elevation, researching soil makeup and preparation techniques will
help your plants thrive.
Before you can start tilling and planting, you need to know the soil. Arizona soil is
primarily made out of topsoil, clay, and a sandy, cement-like layer. The soil is
divided into layers or horizons. These horizons are made of different materials,
which can help or hurt agriculture.
Organic material is in much of Arizona’s topsoil. Organic content helps keep water
and nutrients in the soil and encourages plant growth. While organic matter is in
many types of soil in Arizona, only one percent of the soil is organic content. In arid
conditions it takes years to build up a useful amount of organic material. By using
sustainable farming techniques, organic content will not erode as drastically as it
would with other farming techniques.
Underneath the topsoil there is clay and silt material. Arizona soil has a high
percentage of clay. Clay has a high alkaline content and can prevent the plants from
absorbing moisture or nutrients. While it is virtually impossible to remove the clay
from the dirt, crops such as rice or desert plants have high yield in the arid soil.
Caliche is a sub-soil that is approximately six feet beneath the surface. It is a cementlike layer made up of mostly sand, clay, and silt. While farmers do not usually dig
deep enough to reach the caliche, plants cannot penetrate the ground and water
cannot pass through it. This means trees and larger, older plants are limited in
terms of growth. Even many residential and commercial carpenters must jackhammer the ground in order to construct a well or foundation.
Casa Grande soil has a high clay and salt content. It is a common soil in Arizona and
is often irrigated thoroughly in order to grow most plant-life. While many Arizona
residents do not mind irrigating small gardens, it is not cost effective in large-scale
farming.
Alfisol soil is found in semi-arid or sub humid areas that are usually wooded. Soil in
wooded areas usually contains a higher percentage of organic matter and can hold a
larger amount of water to encourage plant growth. Large-scale farming is rare in
these regions because it could harm the environment and would take a large
amount of energy to prepare, plant, and harvest.
In more desert-like environments, aridsol soil makes up most of the farming soil.
Aridsol soils contain a high level of calcium carbonate and small amounts of organic
matter. Without organic matter, it is difficult for the ground to hold nutrients and
water for plant growth. With additional irrigation, it is possible to coax plant life to
grow.
Found in landscapes such as plains, entisols have a particularly high organic content.
This soil is more resistant to weathering than other Arizona soils but will require
irrigation.
Inceptisol soil forms quickly after small amounts of weathering. It contains a high
amount of clay that can expand or contract depending on the moisture levels. Plants
do not grow well in this soil since the soil tightens around the plant’s root system
when moisture is introduced. This means the plant is unable to absorb water or
move its roots to more moisture.
Soils in higher elevations tend to contain more organic matter and are more
beneficial for agriculture. Mollisol soil can be found in grassy plains or slightly
wooded areas. Since they have large amounts of humus (organic matter) in their
makeup, they can support grains very well.
Like inceptisol, vertisol soil contains large amounts of clay. With montmorillonite, a
mineral that contracts and expands depending on moisture, this soil also harms
plants and can affect harvest.
By becoming educated in soil contents and conservation tillage, it is possible to save
time, money, and resources on your farm. Using methods such as single pass, strip
till, or even no till can help save farmlands from years of erosion or organic material
loss.
Sources:
http://extension.arizona.edu/pinal
http://www.maricopa.gov/planning/PlanningServices/Other/AgriculturalExempti
on.aspx
https://extension.arizona.edu/maricopa
http://www.az.nrcs.usda.gov/technical/soils/shrinkswell.html
http://www.ehow.com/list_7305399_description-soil-types-arizona.html
http://www.ehow.com/about_6577550_type-soil-arizona-have_.html
http://southwest.library.arizona.edu/azso/
http://www.sciencedaily.com/releases/2013/06/130611122008.htm
http://ucce.ucdavis.edu/files/repositoryfiles/ca5505p44-68933.pdf
http://extension.psu.edu/plants/crops/soil-management/conservation-tillage/soilcompaction-and-conservation-tillage
http://www.maricopa.gov/planning/GeneralInformation/FAQS.aspx#8