Issue: September 16, 2000

• Acidifying soil
• Improving soil

Acidifying soil

We have lived in Alaska for the past 35 years, acidic soils that you sweeten with lime. Do we do the opposite here in NM, adding something like Miracid(TM) to the whole general area and possibly more to acid loving plants? Gerry Mosso Deming, N.M.

You have asked a good question, and, although this topic has been discussed in the past, it is worthy of occasional repetition.

The material you would add to your soil depends on which plants you are growing. However, you are correct— we do not recommend adding lime to soil in New Mexico. For plants adapted to calcareous soils, nothing need be added, except the addition of air by rototilling compacted soils. Plants native to more acidic soils will benefit from the addition of sulfur as elemental sulfur or sulfate (Iron sulfate). If plants exhibit symptoms of iron chlorosis (yellowing between green veins), or symptoms of micronutrient deficiency, then application of an acidifier (contains sulfur) and perhaps the deficient micronutrient in a chelated form will help alleviate the problem. Do not expect to see a response after mid-summer. After that time, the leaves are mature and will probably not absorb the missing nutrient. Apply the chelated micronutrient (trace element) in the spring. Sulfur can burn a plant in the heat of summer and is best applied in the autumn or spring.

Fertilizers that acidify may be helpful but are not essential if other acidifiers are used. There are several acidifying fertilizers sold as lawn and garden fertilizers as well as for houseplant culture. They will specify a sulfur content on the label or will specify that they are acidifying.

I suggest that you contact your local Cooperative Extension Service Office. The Extension Service Office is familiar with soil conditions in your county and with the various products sold in your county.

Improving soil

My garden did poorly this year, and I think there is something missing from the soil. What do I add to make the soil better?

This is another topic which has been discussed before, but it is a good one to consider again.

Compost is a safe recommendation for most gardens. It will help with many of the soil problems we experience; however, there are a few exceptions. Southwestern native penstemon plants and some other natives do not need and are sometimes injured by compost. If the compost is not well prepared or not thoroughly composted, it may cause some problems.

However, just adding compost or any other material to the soil is not wise. It would be much wiser to have the soil tested to determine exactly what the soil needs. This is a good time of year to collect and submit soil samples so that you will be prepared for the spring season. Contact your local Cooperative Extension Service agent for information on soil testing sample collection procedures and for information regarding laboratories to test the soil.

Send your gardening questions to Yard and Garden, ATTN: Dr. Curtis Smith NMSU Cooperative Extension Service 9301 Indian School Road, NE, Suite 112 Albuquerque, NM 87112

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.

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