Christine Jones shared important information at the Soil Health Event and on the webinars, and I hope some of you took the time to listen to one or more of the webinars Jones recorded for Green Cover Seed. This article summarizes some of her main insights.
It is important to remember that soil is not dirt. Soil is alive, and life builds soil aggregates, allowing the soil to breathe, absorb moisture, and support a diverse soil biology. We need to change how we look at the soil and see it as a living system.
Christine Jones's key insights:
1) Inorganic fertilizers reduce microbial diversity and function, resulting in compaction due to the loss of soil aggregates.
2) Plant family diversity results in a diverse soil biology, creating a more resilient ecosystem.
3) There are two soil carbon pathways. The liquid carbon pathway is much more efficient at creating soil carbon than the decomposition pathway.
Bacteria, fungi, and all the other life in the soil build infrastructure that increases water infiltration and nutrient exchange, allows the soil to breathe and prevents soil compaction. The soil's microbial diversity depends on the plant feeding the biology through root exudates. Synthetic fertilizers break this relationship between the plant and the soil microbes. Plants no longer need microbes to get nutrients, so they stop feeding the biological body. In one study, synthetic fertilizers reduced the percentage of growth-promoting bacteria living on plant roots from 91% of total bacteria to just 19%. Growth Promoting Bacteria make nutrients available by fixing nitrogen, unlocking phosphorous from the soil, and producing growth hormones and antibiotics.
Everything is connected. Fertilizers are not poison, but they stop the plant from communicating with its soil biome. Placing nitrogen, phosphorous, or fungicide near the seed stops the formation of the rhizosheath. The rhizosheath - the link between the plant and the soil biology - has many functions, such as enhancing water and nutrient uptake and protecting the plants from drought and heat stress as well as disease and insects. The rhizosheath also plays a key role in the liquid carbon pathway, which I will cover in this article later.
A microbial world surrounds us. Remembering that is the key to both human and plant health. 90% of the cells in our body are microbes, and that relationship impacts our health. A plant’s association with its microbiome impacts its health as well. The seed first forms a root, and the rhizosheath forms around the root. Where does the plant get its microbiome from? It came from the plant, from the biology of the seed, and the conditions that produced the seed. Each plant family has its microbial associations. We introduce diverse microbial communities into our soil by planting seeds from different families. Similar biomes compete for the same resources versus a diverse mix of plant families that share resources when necessary.
The Jena Experiment showed the importance of biodiversity when the test area flooded. The areas with a monoculture of grasses died, whereas the same species seeded in diverse mixtures of plant families survived the flooding. The community of plants shared resources for the benefit of the whole system. This has also been shown to happen in drought and frost situations. In one field, they had planted white clover and ryegrass. In an adjacent field, they had planted white clover, ryegrass, chicory, and plantain. The field with white clover and ryegrass frosted, and the more diverse mix did not.
When they measured the brix on each field, the frosted field had a brix of 7, and the field without frost had a brix of 14. What was the reason for the higher brix? One possibility is that the higher diversity of plant families provided greater microbial diversity, and the plants could access more nutrients and water for a higher level of photosynthesis, thus the higher brix. The forage with the higher brix improved rumen function and forage conversion. What is good for the soil is good for the animals.
There are two soil carbon pathways.
1. Decomposition pathway – the breakdown of complex organic matter – cellulose, and lignin into simpler compounds – microorganisms breaking down residue as a feed source to grow and reproduce.
2. Liquid Carbon Pathway – from simpler compounds to more complex compounds. Plants excrete root exudates to feed microorganisms. The bacteria and fungi, along with other soil biology, form the rhizosheath around the root system. The fungi hyphae increase the root surface area 5 to 10-fold; thus, the plant can access more of the soil for nutrients and water. Within this community are nitrogen-fixing bacteria as well as phosphorous solubilizing bacteria, actinomycetes that produce antibodies, and protozoa and other microbes that play a role in providing nutrients through the soil food web. This complex biology produces more complex compounds, such as glomalin, that bind the soil together. The dead microbes also get complexed with minerals to create more stable soil carbon. Plants, through root exudates, build soil carbon 5 to 30 times faster than adding organic matter to the soil. No fungi, no rhizosheath, then no liquid carbon pathway.
Another interesting fact Christine Jones mentioned is that you build more soil carbon without legumes than with legumes. Too much nitrogen suppresses microbial diversity no matter what the source. With too much nitrogen in the soil, the microbes will work to balance the carbon-to-nitrogen ratio and start breaking down organic carbon. Thus, soil is losing soil aggregation compared to building it. She suggested keeping the legumes at 10 to 20% of the stand.
It is important to understand if we work with nature, she will provide everything the plant needs as long as the plant has a strong connection to a healthy and diverse soil biome. Otherwise, the farmer must provide costly inputs and protection for the plant. Let nature do her work.
Resources Christine Jones referenced:
