A new approach to healthy soilJan 27, 2023 10:53AM ● By Bryan Reed
The topic of soil health has taken hold across the agriculture industry, and now with homeowners and consumers as well.
Colorado Department of Agriculture (CDA) recently launched the Saving Tomorrow’s Agricultural Resources (STAR) program to encourage farmers and ranchers to assess their soil health. This free and voluntary program is a great step towards defining soil health practices and educating consumers about the importance of looking after this vital resource.
Producers complete a questionnaire regarding their soil management practices. Based on their commitment to soil health and the results of their soil profile analyses, the CDA awards a one- to five-star rating, with a five representing a complete commitment to soil health.
Farmers and ranchers commit to the program for three years and do evaluations each year to grow their STAR rating and demonstrate their ability to grow crops while conserving water, reducing erosion, sequestering carbon and promoting soil microbiology. Another component educates consumers on interpreting the STAR rating when purchasing from producers whose practices they support.
The USDA’s Natural Resource Conservation Services (NRCS) division was able to succinctly define soil health management based on four components that even home growers can work towards improving. The STAR program is based on these principles:
MAXIMIZE SOIL COVER
In our desert climate, mulch is important for both conserving water in our plants and for keeping weeds down. A patch of lawn or a pasture of native grass can protect the soil from weed seeds and keep the soil temperatures moderated in the summer heat and winter cold.
Leftover plant debris in the garden can insulate soil microbes from intense freezing while decomposing and releasing stored nutrients back into the ground.
Cover crops or plant residue also stops wind and collects blowing snow for a good spring moisture bank. That same residue protects the soil from heavy rains that can wash away topsoil or pound down our heavy clay soils.
MAINTAIN LIVING ROOTS
Keeping living roots in the soil year-round is amazing for soil microbe health. Roots gain a constant feed supply, both from root exudates and from decomposing roots from last season’s crops.
All living roots have the capacity to hold more moisture in the soil. In addition, last year’s crop roots turn into this year’s organic matter, acting as a sponge to retain moisture in the soil for longer periods of time. Homeowners are a step ahead as most already have trees and shrubs on their property. The NRCS makes it clear that a 1% increase in organic matter can hold up to 20,000 gallons of water per acre.
Cover crops are an option for us gardeners as well. I scattered oats, buckwheat and winter wheat seeds throughout my gardens in early September and they filled the space around my vegetable plants.
This year I used an all-edible Milpa cover crop mix consisting of beans, seeds, mustards and radishes. I planted it in areas where the summer roots and greens had been harvested. They grew in quickly and held their vitality through the first early frosts and well into late November. The legumes fixed nitrogen, and all the other plant species fed a variety of microbes and put roots into varying depths of the soil.
Tilling and turning the soil is harmful to microbe-populated root zones. Most of the beneficial bacteria populate the one-millimeter zone around the plant’s roots known as the rhizosphere.
Uprooting plants removes the rhizosphere from the soil and takes nutrient cycling bacteria with it. Tilling and turning up the soil exposes microbes to UV rays which kills them and shreds fungal colonies.
Many large-scale growers are adopting no-till practices in their fields since plowing and tilling takes labor, fuel and wear and tear on a tractor. By reducing the amount of tillage in our gardens, we can actually build soil structure and keep those earthworm holes intact so that irrigation water has a way to get to the plant roots.
Using companion planting not only helps crops to thrive, but it also helps to conserve water.
Julio Franco at Texas A&M planted watermelon, hot peppers, okra and peanuts in two identical acre plots over two years. He planted one in quarter strips of each crop while the other was planted one crop per row in a repeating pattern across the field so that every crop was next to another crop.
The yield from the interplanted field surpassed the traditional strip plantings both years. He found that the watermelon cooled the soil for the hot peppers and the okra provided shade for the peanuts.
In the first plot, crops competed with each other for root space and nutrients while the intercropped plots complemented each other and aided in their growth. Franco also found the intercropped plot used less water.
Another approach to biodiversity is to graze fields with livestock to incorporate their manure and cycle nutrients. Animal manure has classes of actinobacteria that can’t be found anywhere else.
As home growers, we can incorporate manure into our gardens or composting to gain the benefits of actinobacteria without the added responsibility of managing livestock.