There are three basic types of soil in Northern New Mexico: caliche, adobe and sand. All are alkaline, with a pH often well over 7.0, and tend to contain abundant quantities of sodium, calcium and potassium. Caliche, adobe, and sand all lack organic matter, the nutrients and organisms of which are essential for sustaining high quality plant growth and production.

Caliche is made up of sand, gravel and clay. Adobe is essentially fine clay. Neither soil type is easily penetrated by water. Sand, on the other hand, allows water through but has a limited ability to hold nutrients or moisture.

When cultivating our soil for the first time there are three steps to follow:

1. Clear the ground of weeds and brush. Annual weeds may be pulled up, hoed, dug out with a spade or roto-tilled. Perennial weeds must be dug out and discarded. Avoiding leaving plant roots behind. In locations where you have perennial weeds, or a combination of annuals and perennials, you might first apply a herbicide. We suggest using a product such as Roundup™ or Finale™. These herbicides both work systemically, that is to say, they enter through the leaves and travel down into the plant’s root system. They are inert upon reaching the soil, thereby avoiding soil toxicity.

Herbicides work best in consistent daytime temperatures of 70-80 degrees and in an acidic water base. They take about 5 to 10 days to be effective and may require more than one application on tough weeds. Once the treated plants appear brown and dry, dig or pull them out removing as much of the plant as possible. Some soils may need to be soaked to soften them sufficiently to loosen and remove any remaining plant roots.

2. To add amendments, examine your soil and determine its type. If you aren’t sure what type you have, bring a sample to the nursery for our professionals to examine. You may want to have your soil tested by a laboratory. Contact the Santa Fe County Extension Service (471-4711) for further information on testing. In our experience, soil testing of home plots is usually only necessary when you suspect toxic contamination.

3. Add organic matter to your soil at the rate of 9 cubic feet of compost, peat moss or manure per 100 square feet of garden area. We also recommend adding natural minerals to soften and acidify the soil at the rate of 21 lbs. per 100 square feet. We suggest Ironite™ or the combination of greensand and rock dust. Then apply an organic base fertilizer (like Gro-Power Plus™) at the rate of 2 lbs. per 100 square feet. Spade or roto-till these additions into the soil. Break up any remaining dirt clods to the size of a large walnut or smaller. Finally, rake the ground level to facilitate even water penetration and to regulate air flow and soil temperatures.

Organic and natural amendments improve our soils in many ways. Organic matter improves soil structure enabling clay soils to expand by creating air spaces for roots to grow and helping sandy soils to retain nutrients and moisture. When organic matter is applied as a top-dressing (mulch), it saves on water, promotes even soil temperatures (thus extending the growing season), acts as an effective wind barrier and adds nutrients and organisms to the soil.

Natural minerals acidify alkaline soils, breakup tight clays and enrich the soil’s natural mineral content, which give our fruits and vegetables their wonderful flavors. The addition of organic fertilizers give the extra nutrients needed to sustain quality plant growth and production. Note: Chemical fertilizers feed plants but do not nourish the soil and can, in fact, tighten soils further. Chemical fertilizers are fine to use in moderation, but should be avoided during periods of hot, dry and windy weather or drought since they may promote tender growth, making plants more vulnerable to adverse weather conditions. Likewise, chemical fertilizers should be used with care after mid-August as they often stimulate new growth, which does not have time to mature before the first hard freeze.

Over time, plants, soil organisms and other environmental factors will consume the amendments you have put into the soil, so periodic replenishment is encouraged. Once or twice a year, ideally in the spring and fall, top-dress (mulch) your lawn, garden and landscape with organic matter. Apply 1 to 2 inches of it (we recommend Payne's Organic Soil Conditioner™, a cottonseed-based compost) for spring mulching and 2 to 3 inches for fall. Lawns usually only require 1/4 to 1/2 inches of mulch. Replenish natural minerals 1 or 2 times each year (April and October) and organic fertilizers 2 to 4 times per year depending on the plants being grown.

For more information on soil-building in Northern New Mexico, contact Sam McCarthy, the Compost King, at POSY (Payne's Organic Soil Yard), at 505-424-0336. For directions to POSY, where you can purchase top-quality organic soil amendments in bulk, click here.