Category Archives: Issue 18

The Soil Will Save Us, by Kristin Ohlson

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This very readable book describes how sustainable agriculture can make us healthier, reduce pollution, and counteract climate change. It provides a comprehensive and eye-opening look at how farmers and organizations in several countries use innovative techniques and ancient traditional methods to build soil and provide food in a sustainable manner. 

The author meets and interviews key soil researchers and innovative farmers and practitioners, including Alan Savory (founder of the Savory Institute), Courtney White (founder of the New Mexican organization Quivira Coalition), and Gabe Adams (a successful no-till, cover-crop farmer in North Dakota). She reports on the work of research institutions such as New Mexico State University. She also points out the damaging impact of big money from petroleum, fertilizer, and chemical companies on government agricultural policies, university agriculture departments, farming practices, and ultimately, the nutritional quality of the food we eat. 

Conventional wisdom has assumed that over-grazing by cattle has caused degradation of the land. But Alan Savory’s research shows that putting large numbers of cattle on small sections of land for a short time and then moving them can result in richer and more productive soil. Saskatchewan farmer Neil Dennis found that the benefits of running a large number of cattle “were multiplied by having lots of them there: lots of hooves breaking up the hard surface of the soil, lots of grasses trampled into the ground, lots of grasses being tugged and bitten, causing the plants to pulse carbon sugars into the soil, and lots of nutritious dung, urine, and hair spread around for insects and microorganisms to break down.” (p. 96)

Ohlsen describes exciting New Mexico State University research by Douglas C. Johnson. Planting over cover crops instead of clearing the previous year’s debris increased the soil’s organic matter by 67% and water-holding capacity by more than 30% in two years. There are obvious lessons here for creating sustainable agriculture in arid New Mexico.

The author portrays problems, including difficulties getting research funding that is not from fertilizer and pesticide companies. Despite this, there is much hope in the book. A diverse of people, including farmers, ranchers, hunters, preservationists, and wilderness advocates (all of whom love the land), are coming together to create solutions that will work for everyone.

Reviewed by Linnea Hendrickson, member of Elder Activist Readers ) EAR)

Soil Moisture

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In soil, moisture is found in the spaces between the particulate matters of sand, clay, and silt. Loamy soils are a friable mixture of the three types and are able to hold moisture better than any one type alone. Soil is generally 45% particulate matter, 50% pore spaces which hold moisture and air, and 5% organic matter. (In New Mexico, organic matter averages only 1–3%.) A plant’s root system depends on soil moisture to protect it from swings in temperature. As the planet warms, soil moisture decreases and stabilizing existing moisture becomes more critical for plant survival.

Photo: Gabriel Jimenez / unsplash

There is a National Coordinating Soil Moisture Monitoring Network (NCSMMN) with 1,200 stations across the US. They advise farmers and ranchers using mathematical modeling of evapotranspiration and sensed soil moisture from its network. This data can help ranchers manage forage and the number of cattle on a parcel of land as well as help farmers decide which crops to plant and the timing of planting. In general, fruits, vegetables, nuts, and medicinal herbs are more vulnerable to changes in moisture than field crops.

Soil moisture can be measured by high tech using satellites or simply using a trowel or auger in your garden. Drill or dig down six inches and feel the soil – it should not crumble in your hand. If it does, more water is needed.

To learn more about soil in NM, check out NM Healthy Soil. Their premise begins with “Soil is a living ecosystem which sustains plants, animals, and humans.” Adequate soil moisture makes this possible.

by Sue Brown with input from Robert Flynn, NMSU Extension-Artesia

MULCH

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Not much beats mulch for retaining soil moisture in a dry climate like New Mexico’s.

Mother Nature covers the ground under plants with their cast offs, so humans would be wise to leave them there.

So what exactly is mulch? Mulch is often confused with compost, which is the dead remains of living matter that have been digested by microbes, insects, worms, and fungi to create rich soil. Mulch is simply any ground cover. This protective layer could be leaves, straw, wood chips, grass clippings, pecan shells, newspaper, black plastic, or even rocks that are placed around the base of a plant.

Reasons to use mulch:

  1. Slow the evaporation of water.
  2. Cool the ground around the roots in summer.
  3. Prevent the roots from freezing in winter.
  4. Discourage weed seeds from sprouting or finding light.
  5. Decorate or define planting areas.
  6. Keep soil and soil-borne diseases from splashing onto plant leaves during rain or watering.

Factors affecting your choice of mulch material:

  1. Price – what you can access for free or find readily available will be a tempting choice.
  2. Weight – if the land is sloping, a heavier mulch will stay in place better in wind and rain.
  3. Color – a dark mulch will retain more heat than a lighter mulch, and some folks like to expand the outdoor palette or give distinct areas contrasting colors.
  4. Durability – clearly rocks last longer than newspaper, but they’re also harder to get rid of if you change your mind.

Cautions and considerations include:

  1. Weed killers in the mulch (such as in grass clippings) could kill your plants, so know your source.
  2. Overheating of the ground and die-off of soil life may occur when black plastic is used.
  3. Colored dyes in newspaper or magazines rarely contain lead these days, so no worries on that front.
  4. Soil compaction from a heavy mulch such as river rock on clay can block root growth.
  5. Seeds in straw or especially hay can sprout in mulched beds.
  6. Matting of unshredded materials may prevent moisture from penetrating to the root zone.
  7. Weed barrier (aka landscape fabric) sheds microplastics into the soil that plants then take up.

Free sources of wood chips are:

—East Mountain Transfer Station, 711 NM-333 in Tijeras, 505-281-9110, open 7am-5pm every day. You can load yourself or pay them $5/scoop.

—ChipDrop puts you on a list that tree trimmers will call if they come to your area. You have to take their whole load, which could be as much as ten cubic yards.

—If you or a neighbor has a tree trimmed or removed, you can ask the arborist to leave the chips in your driveway.

by Donna Deitweiler

Cover Crops

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Cover crops are grown for a variety of reasons. In fact, it is important to identify your goal before planting a cover crop as they differ in their ability to help the soil and to help you. Goals for planting cover crops can be:

  1. to decrease soil compaction
  2. an attempt to interrupt the cycle of disease
  3. to increase organic matter
  4. to retain of soil moisture
  5. to decrease wind and soil erosion
  6. to catch nutrients so they don’t leech away
  7. for carbon fixation
  8. to add specific nutrients as nitrogen or potassium.

New Mexico Extension Services has an online cover crop publication which helps the reader know which cover crop to choose for their own goals.

Cover crops for increasing soil moisture are often called ‘living mulch.’ Because they are perennials, they also sequester carbon. Clovers, such as Dutch White and Ladino do not grow very tall. Clover can attract pollinators, add nutrients to the soil, and tolerate the heat and cold of New Mexican weather. As all clovers, it has shallow roots which don’t tolerate drought as well as some other plants do. A loam soil would provide more soil moisture in times of drought. Alfalfa can be used as a cover crop and does not require as much water as when being grown commercially. Vetch does well in NM and historically there is not a nematode problem in NM which would prevent using vetch.

by Sue Brown with input from John Idowu-NMSU Extension Service, Las Cruces