April 9, 2011

1 - There are several reasons that New Mexico soil is too hard to dig into, but a common cause this year is the fact that the soil is dry.

Yard and Garden - April 9, 2011


I was all ready to plant some tomatoes and peppers today and found that when I started to dig my holes, just a couple of inches down I hit rock hard 'soil'. I dug as much as I could and have soaked the holes with water to try to break it up deep enough for planting.

What can I add to this 'soil' to turn it into something more suitable for gardening/planting? And how much of whatever material that you suggest, should I use? I had assumed that my location had been used as a garden area before as it is fenced and has water nearby. And since the irises in the iris bed are coming up looking healthy and vibrant, I was further convinced that I could dig a hole, throw in some miracle grow and plant to my heart's content! My garden is located about 10 miles south of Deming, NM.


Hard soil is not uncommon in New Mexico. It may be due to rocks (many small rocks), caliche (soil particles cemented by high calcium concentrations in the soil), or just the fact that when our soil is dry, it is often as hard as pavement. Dry soil can turn a shovel into a pogo stick.

If the problem is caliche, a solution may be for you to make raised beds or container gardens. You can try to dig out the caliche, but it is much easier to build above the soil, especially for flowers and vegetables (trees and shrub planting require very large raised beds and depth considerations). An advantage of raised beds is that you can engineer the soil (mixing purchased components and some native soil) to create the ideal soil for the plants you intend to grow. As you water these beds and add organic matter (and perhaps sulfur) to the soil, it may begin to decompose the caliche below and in time may make a deeper soil available for gardening.

If the problem is just dry soil, and this has been a very dry year for most of New Mexico, then irrigate the soil slowly to moisten the soil. You will find that the soil becomes much more workable when it is moist. A soaker hose, sprinkler on low, or even a hose just trickling in the area to be prepared can help. When you can work the soil, add organic matter (compost) that will help increase the moisture holding capacity of the soil and improve its structure allowing better aeration and water penetration. It will then be ready for planting.

Your local NMSU Extension Service County Agent can help you determine the specific nature and problems with your soil in your location. They can also advise you regarding collecting samples for soil testing and help you interpret soil test results. They can also tell you where to send your soil sample for testing. Soil testing is a good idea when starting a new garden, and periodically thereafter.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!