CIBOLA COUNTY, N.M. – As I talk with gardeners in the Grants and Gallup area, I come across those that lament the soil they have to deal with, CLAY. This clay is used in making clay pots. When wet it becomes a gummy, gooey mass that sucks off your boots and puddles in low areas before drying out and reverting to a rock-hard brick. Plants have a hard time dealing with the large cracks in the soil that occur as the soil dries out. Too much water fills the air pockets and plants die from lack of oxygen. There are things that can be done to the soil.
First, we need to examine what makes soil. What is this brown stuff we call soil? We take it for granted as we walk on it. Magically it produces the food we eat, flowers of magnificent beauty, and the canopy of trees that provide shade.
Soil is a combination of:
o Sand is a large particle that can be seen with the naked eye. When wet, it falls apart. o Silt is smaller than sand and hold water better. When wet, it holds it shape and is often compared to the mixture of butter and flour. Its grain is a size in between sand and clay. o Clay is the smallest particle and cannot be seen with the naked eye. When wet, it holds it shape and is sticky. o Organic matter is the decaying of roots, leaves, and stems of plants. It is also decay of bugs, animals, and their manure. Where there is more moisture, this decomposes to enrich the soil. Organic matter is also the living portion of soil. Healthy soil is teaming with life: bacteria, fungi, and macro-organisms. o The best soils contain a balance of all of the above. The plants have a good substance to support growth and it provides nutrients, water, and air that plants need to grow.
The solution to a garden with clay soil is to add organic matter. You have a wide range of products to choose from and the trick to find something that works for your situation. o Any compost, home-made or purchased is a great amendment because it has already broken down and can be added to the soil and be planted immediately. o Wood chips, straw, dry leaves, and hay are often used but need time to break down before planting a garden. Best if composted a year first. o Spoiled or fresh alfalfa hay or hay cut in the green stage can be mulched one year then plowed into the soil the next year. o Pine needles acidify the soil, but they break down very slowly and are better used as mulch. o Grass clippings make a good mulch but they tend to mat and can sometimes smell when not well mixed in compost or soil. They do make a good weed barrier when matted. o Know where your grass and hay originate! Make sure no herbicides to control weeds have been applied. o Planting a cover crop over part of your garden for a season is another inexpensive way to improve the soil.
Soil Amendments to avoid or use cautiously. o Wood ashes raise the pH of the soil and add salts. In New Mexico our soils already have a high pH and extra salts make it harder for plants to grow. o Sand when added to clay creates a cementlike compound. o Peat moss is nonrenewable and is difficult to wet once dry.
o Gypsum is sold to loosen clay soils but compost is a better and cheaper choice.
o Fresh manure has excessive salts. It is best applied after the growing season is done. Water it in and allow it to overwinter before using.
Adding compost to clay soils provide the layer of particles needed to allow water and air to be accessed by plant roots and to grow. Unfortunately, soil reverts back to its prominent structure and by the next year and the soil is hard and gooey again. Having a compost pile near your garden to replenish the soil for vegetables gardens, flowers, and bushes is an important element to your garden when you are dealing with clay soil.
Another option is to use pots and raised gardens for everything but large trees. Wood or metal structures are filled with good gardening soil for vegetables and flowers. Soil dries out faster in a container so plants need more frequent watering than those planted in the ground. A drip system can be set up to reduce the need for hand watering. This is a more expensive set up than amending the soil, but other than small adding of nutrients, it you don’t have to deal with clay soil yearly.
The next few articles will be on gardening systems developed for dry areas of the world that are challenges to gardening: Hugelkultur, Keyhole, and Permaculture.
Edith Iwan is a Cibola- McKinley County Master Gardener who lives and works in Thoreau. As a Master Gardener she assists the County Cooperative Extension Service in providing accurate, research-based gardening information to county residents. If you have any gardening questions, please call the NMSU Cibola County Extension at 505-287-9266 or NMSU McKinley County Extension at 505-863-3432