Soil Regeneration and Health

Amy Larsen, Dr. Johnson, and Tom Dominguez Beside Johnson-Su Bioreactor Compost Bin
Amy Larsen, Dr. David Johnson, and Tom Dominguez Beside Johnson-Su Bioreactor Compost Bin (Photo Taken by Adrienne Rosenberg)

Soil health may be the most important factor for farming success, especially in the arid Southwest. Today's soil is challenged by the effects of modern human inhabitance such as salinization, pollution, soil loss, and reduced water retention. Although we often think of soil as inert and uniform dirt, it can be viewed as comprising three major components: chemical, physical, and biological. Together these make any soil sample deeply complex.

For Amy Larsen, Senior Research Assistant, the solution for vibrant soil is growing the microbial community or microbiome. Larsen is currently initiating a series of trials with a static, aerobic composting process that was designed and developed by NMSU researcher Dr. David Johnson and Hui-Chun Su Johnson. By encouraging microbial communities to increase both in numbers of organisms and in diversity, the Johnson-Su bioreactor composting system produces a "high quality" nutrient-rich, fungal-dominated, high microbial biomass, and biodiverse compost. Based on previous experiments, soil inoculated with the bioreactor compost benefits with faster and greater biomass growth, a more efficient transfer of carbon, reduced soil respiration rates, and increased soil fertility. Larsen intends to observe and measure the cultivation of diverse microbial communities and the potential for increased crop yields. In addition, she seeks to standardize the system so that everyday farmers can inoculate their soils with a radiating, fungal dominant network of interacting beings without the need for a lab or a microscope.

SASC Alcalde Publications

  • Compost as a Microbial Inoculant (Poster; PDF)
    Created by Amy Larsen and presented at the 2018 Soil Science Society of America, this poster illustrates the current Johnson-Su Bioreactor Composting System study conducted at SASC Alcalde.

Additional NMSU Publications

Power Points, Circulars, and How-to Guides

  • Best Management Practices: Johnson-Su Composting Bioreactors (Powerpoint, PDF)
    Compost-amended soils have existed for over 5,000 years in the tropical soils (terra preta) of Amazonia, more than 4,000 years in Asia and Japan, over 2,500 years as plaggen soils in the Netherlands, more than 850 years in cultivated soils called chinampas in Meso-America, and 1,000 years in the altiplanos of Bolivia. Some of these soils, created as a consequence of human activity, remain more fertile and more productive than the surrounding soils to this day. This longevity of soil fertility provides good evidence that composting is beneficial, and if we are to achieve long term sustainability in our agricultural systems, it may be advantageous for us to start emulating the composting activities of nature and our ancestors. This document guides the reader through building a Johnson-Su Bioreactor.
  • Circular 650_Sulfur and New Mexico Agriculture
    Sulfur-deficient soils are often low in organic matter, coarse textured, well drained, and subject to leaching because sulfate is mobile in the soil. In semi-arid regions, SO4-2 can accumulate in the lower soil profile as soluble gypsum. The S status of New Mexico's soils is not well defined, and S effects on the growth of New Mexico crops have not been extensively researched.
  • Circular 656_An Introduction to Soil Salinity and Sodium Issues in New Mexico
    Salts are necessary for providing many of the minerals that both plants and humans need in order to be healthy. Too much salt is unhealthy for humans as well as plants. High salt in the plant root zone interferes with the uptake of water and can cause death. It does not matter to the plant what kind of salt it is. Thankfully, plants have different levels of tolerance to salts found in the soil or in irrigation water. Since salts can conduct electricity when dissolved in water, we can measure the total "saltiness" of a soil by using a water extract and measuring how well the water conducts electricity. We can combine this measure of saltiness with knowledge of how plants respond to the salt to improve productivity using optimum soil management and plant selection.
Amy Larsen Holding a Hand Full of Soil
Amy Larsen Holding 5 Month Old Bioreactor Compost (Photo Taken by Adrienne Rosenberg)
  • Guide A 114_Test Your Garden Soil
    Soil tests provide a scientific basis for regulating available plant nutrients. Recommendations on soil management practices are based on test results. Tests on a sample that does not accurately represent your garden or field's soil are likely to be misleading. The directions in this NMSU Guide can help you take a representative sample.
  • Guide A 146_Appropriate Analyses for New Mexico Soils
    Soil testing helps us understand the soil environment in which our plants must survive. A complete understanding of the soil would include its physical, chemical, and biological properties. Management practices affect all three of these categories. Soil testing provides a "snapshot" of what conditions were like at the time of sampling, and this allows farmers and homeowners to plan their management practices for the coming growing season. The focus of this publication is to provide guidance for people interested in knowing more about their New Mexico soil from a chemical and physical perspective.
  • Guide A 148_Understanding Soil Health for Production Agriculture in New Mexico
    Since soil is such an important component of the natural ecosystem, careful management of the soil is essential to sustain its utility. Conventional commercial farming depends heavily on the careful management of soil nutrients to promote adequate crop yields of food, feed, and fiber. This has resulted in the development of precise nutrient analytical methods with accompanying recommendations to address nutrient deficiencies in different soils that are used for farming. While this strategy has improved productivity over a long period of time, scientists are now finding that managing soil for nutrients alone may not lead to sustainable crop production in the long term. Other aspects of the soil, including aggregate stability, infiltration rate, salinity, sodicity, and mineralization potential, need to be addressed to attain the goal of sustainable crop production (Idowu et al., 2008).
  • Guide H 637 PH 4 206_A Practical Way of Measuring Soil Moisture
    Irrigation efficiency in orchards is extremely important in the arid West where almost all the water needed come from irrigation water. Orchardists should check water penetration after each irrigation to ensure the appropriate soil moisture depth for optimum tree growth. Although this guide is geared to pecan growers, it is generally applicable to other orchardists.

NMSU News Center

Additional Links


  • NMSU: Understanding Western Soils (Animations and Videos)
    This series provides guidance on how to sample soil for analysis and includes visualizations related to soil properties and water infiltration. Concepts such as particle size, soil water-holding capacity, runoff, leaching, sodium adsorption ratio, sodic soils, and saturated paste are explored. Short video demonstrations assist with teaching or learning. The series focuses on arid soils, such as those found in the American West.
  • NRCS: Guide to Soil Texture by Feel
    Not all laboratories evaluate soil texture as part of their normal fee structure. Many labs will estimate texture or perform a specific test to determine soil texture for an additional fee. Texture can be estimated at home or on the farm with the "feel" method by using the USDA NRCS's guide found in Gee and Bauder (1986).

Johnson-Su Bioreactor Compost

Nematode in Bioreactor Compost 400 tot. mag.
Nematode in Bioreactor Compost 400 tot. mag. (Microscope Photo Taken by Amy Larsen)