Principles Lay Foundation for Healthy Soils
Soil health is a largely underrated topic in mainstream society. Even in agricultural circles, where emphasis on the land and soil is strongest, misconceptions still linger on.
Archuleta, a Natural Resource Conservation Service (NRCS) soil health specialist based in North Carolina, travels the country "speaking for the living soil" to groups to foster a better understanding of soil health and teach producers how biomimicry strategies and agroecology principles can make their operations more sustainable.
This is accomplished by first demonstrating the differing soil properties, such as stability and water infiltration, of conventionally-tilled versus no-tilled (undisturbed) soils with the slake test. The slake test measures the stability of soil when exposed to rapid wetting. This and other visual demonstrations help to bring groups together in a single focus, setting the stage for listeners to better grasp soil ecology principles.
While NRCS teaches only four foundational soil ecology principles, Archuleta expands his focus to eight to help producers understand how farming in nature's image can facilitate healthy soil function, and successively, healthy plants and animals. The first four principles deal with the human aspect, while the remaining four involve soils' ecological characteristics.
The human component
Understanding the ecological context means recognizing the farm and humans are still part of the ecosystem. Commonly, producers tend to separate how the farm and ranch function from the natural system, thinking they work differently, when in reality they do not.
The microbe, the cow, the human, the plant – all are interrelated and connected to each other working together to form the whole of a pasture ecosystem.
In the second principle, Archuleta stresses human integrity must be cultivated alongside ecological integrity to foster commitment from land stewards. Tenacity, patience, and open-mindedness are necessary.
Archuleta advises producers follow holistic management principles as a decision-making framework in his fourth principle, quoting Benjamin Franklin, "If you fail to plan, you are planning to fail."
The last human-related principle is to reduce chemical, physical, and biological stresses on the soil ecosystem. Chemical stresses include herbicides, insecticides, fungicides and fertilizers. Overuse of these chemical tools can suppress or harm soil biology diminishing soil function. Physical stresses include tillage and over compaction. Biological stress is overgrazing and continual monocultures. Though grazing is a natural occurrence, Archuleta notes proper grazing where animals are moved often and pastures have long recovery periods is desired.
Another ecological principle to ensure a healthy, functioning soil ecosystem is to grow a living root in the soil year-round. The living root acts as an energy conduit for the sun. Plants are energy transformers.
According to Archuleta, the plant is a biological primer which converts solar energy into photosynthetic byproducts, also known as root exudates, which feed the soil ecosystem. This liquid carbon pathway leaks carbon, protein, sugar compounds, and hundreds of other compounds into the soil which feed a myriad of organisms that live there. In turn, soil organisms cycle nutrients and services back to the plant helping it grow.
Along with maintaining year-round greenery, Archuleta emphasizes having biodiversity by maintaining a mixture of plants and animals in the system. Diversity above ground will increase diversity below as well. For cropping operations, integrating livestock into the farming system will build ecological and economic resilience. Prairies and forests have diverse plants and animals all the time. This is an important principle which must be applied for healthy soils.
Soil health check-up
"On pastures, what I'll do is take a shovel and dig into the soil to see if the five spheres are present," Archuleta says.
When looking at the five spheres (listed below) Archuleta says a healthy soil will have the following:
- Detritusphere – residue covering the surface (i.e. litter) consisting of dead plant and insect material, decaying fecal matter
- Rhizosphere – 1-2 cm area surrounding roots will have biotic glue and fungal hyphae bound to roots and soil particles
- Aggregatusphere – should look like cottage cheese, porous, allowing air into soil
- Drilosphere – part of soil influenced by earthworms, should have 4-5 earthworms per shovelful
- Porosphere – macro and micro pores, allowing unobstructed flow of water and air, low bulk density, highly permeable
A soil test known as the Haney-Brinton Test which measures active carbon pools that drive nutrient cycling in soil can also be useful. Archuleta explains organic matter is approximately 58% carbon. In a soil with 1-2% organic matter there is about 12,000 ppm carbon. The "active" portion of this carbon pool is even smaller, about 80-100 times.
"It (active carbon pool) is like the sugar, the ice cream, the thing that is easily digested by microbes," says Archuleta. "If the Haney test picks up small pools of organic nitrogen and carbon that drive nutrient cycling in soil, that's one indicator I use that the pasture is healthy."
Once a baseline has been established, producers can take proactive steps to begin improving upon their soil's health.
"The most important thing you can use is adaptive grazing management," Archuleta says. "Learn how to graze properly. Know how much your cows are eating. Use adaptive management and be out there all the time watching and observing the animals' behavior."
Adaptive grazing mimics nature and adapts to changes in the system similar to the natural world.
"Bison and giant herds of ungulates grouped together and moved often because of predators," says Archuleta. "The predator we want to use is the hot wire fence."
Large fields should be broke up into smaller paddocks with interior fencing and animals rotated through to ensure proper recovery periods for grazed plants. Gallagher offers many fencing components options for this purpose, including the Ring Top Post which makes putting up temporary electric cross-fencing for paddocks fast and easy.
Controlling density, not number of animals, but the size of the area they graze, combined with timely moves will help improve soil function in grazing systems by more evenly distributing manure and urine. This assures every square foot of the soil is fertilized and soil microbes are receiving the nutrients they require to help the rest of the system function properly.
Finally, Archuleta recommends producers read books like Allan Savory's Holistic Management: A New Framework for Decision Making and Dr. Patrick Levelle's Soil Ecology to learn how to look at the water and mineral cycles of their soils and how these cycles influence pasture ecosystems.
"To understand how the cow and the soil microbe are connected, how the system works," says Archuleta, "that's the key to this whole thing."
Authored by Jesse Bussard, an agricultural writer based in Bozeman, Montana.
Detailed explanation of five soil spheres: http://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download?cid=stelprdb1259408&ext=pdf
NRSC Soil Health Key Points: http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1082147.pdf