How do plants farm soil microbes?

Source: How Plants ‘Farm’ Soil Microbes and Endophytes in Roots

UPDATE: Dr. White sat down with Dr. Fitzpatrick and Jeff Lowenfels to discuss rhizophagy. Click here to view the webinar. (Jan. 15, 2021)

A summary of James F. White’s presentation at BioFarm, 2020 (Nov. 12, 2020). 

The rhizophagy cycle is an amazing process recently discovered by James White’s laboratory at the University of New Jersey, by which root tips “ingest” bacteria and absorb nitrogen and phosphorus and other nutrients from them.

The microbes pictured here in roots are called endophytes because they can live inside plants. The bacteria are attracted to the root tip by root exudates. They then enter the root where the cell walls are dissolved using superoxide, allowing nutrients to leak out to the plant. But the plant does not kill the microbes instead the microbes stimulate the formation of root hairs, which are escape routes for the microbes.

After ejection from root hair tips, bacterial cell walls re-form. The bacteria fatten up and are soon ready to acquire soil nutrients and become another meal for the plant.

Source: How Plants ‘Farm’ Soil Microbes and Endophytes in Roots

Not only does rhizophagy provide mineral nutrients, it is also the stimulus for formation of root hairs, which are critical to the establishment of a healthy root as can be seen in this photo of a plant root with and without endophytes.




Soil Health Improvement Tracking

Microbial biomass (MB) is the best single indicator of soil health (Doran, 2000). Microbes feed and protect plants, build soil structure which prevents erosion, increase water holding capacity, and build soil organic matter (SOM). MB is low in any situation that is harmful to plant growth (and vice versa) and protects against pathogens, thereby reducing the need for pesticides. MB can predict success before plant outcome. The Fungal:Bacterial ratio (F:B) of the MB provides crucial information regarding colonization by Arbuscular Mycorrhizal Fungi (AMF), and the recycling metabolic processes of saprophytic fungi (SpF).

Soil stewards all over the world are seeking to understand the microbial levels in their soil and the ratio of fungal to bacterial life. The higher the microbial biomass, the more nutrients will be available to plants naturally, decreasing or eliminating the need for chemical fertilizers. Higher fungal to bacterial ratios are critical for building soil structure that prevents erosion and runoff off of pollutant chemicals while building moisture holding capacity of the soil and sequestering carbon.

Soil health is fast becoming one of the most important factors in agriculture and in the growing efforts to improve the earth’s stock of agricultural land. Farmers, industry, and environmentalists are looking for cost-effective and reliable ways to measure soil health and to assess impacts of progressive changes to soil and harvest management.

Testing soil in homogeneous sections at similar stages of the growth cycle can set a baseline for microbial biomass and fungal to bacterial ratio. That baseline can be used to assess how different stewardship practices are impacting the soil and allow for refinement to soil management plans and show soil health improvement over time. While every soil steward’s situation is unique, microBIOMETER® can help measure, follow, and assess efficacy of improvement to soil health.

Why is microBIOMETER® the best test for soil health?

soil health testUntil now tests for microbial biomass were expensive and time consuming. microBIOMETER® costs $13.50 or less and takes 20 minutes with results read by your cell phone.

* Only microBIOMETER® identified soil health in a U. of Tennessee study of soil health test methods including Cornell, USDA, Alabama and other soil health panels costing ten times as much.

* There are >2 million academic articles that use microbial biomass laboratory tests as proof of soil health. However, lab tests cost $100 – $500. microBIOMETER® takes 20 minutes at an average of $10/test.

* Soil microbes quickly die when removed from the soil. microBIOMETER® reveals the microbial biomass of your soil as it exists. Lab tests use dried soil and we have demonstrated that 80% of microbes die upon drying.

* The low cost and simplicity of microBIOMETER® means you can use it to monitor what is happening in time to make necessary corrections.

* microBIOMETER® can tell you if you are increasing your soil organic carbon. For instance, an increase in microbial biomass of 100 ug MBC/g per acre of agricultural land is equal to an elephant’s weight in microbial biomass, which is about 400 lbs of microbial carbon or >1450 lbs of CO2 equivalents. This can be accomplished by switching from heavy chemical fertilizer use to regenerative practices.

“Farming is more fun with microBIOMETER®.”

soil microbesmicroBIOMETER® helping increase soil health in Brazil.

Marcelo Chiappetta of Chiappetta Agricultural Company in Brazil shared with us how microBIOMETER® is assisting them with their soil management efforts. Their main agricultural crops are soybeans and corn. Between those crops, as they have a temperate climate during the winter months in southern Brazil, is the possibility of growing a cover crop mixture of radish, vetch, rye, and oats and feeding the soil with different roots.

Their microBIOMETER® results pictured here from top to bottom are:
  • Degraded Soil
  • Native Forest 1
  • Native Forest 2
  • Cover Crop Mixture
  • Alfafa

Analyzing your fungal to bacterial ratio data.

microBIOMETER® is a great tool for us to manage our soil health. As parameters to compare and create our own soil measurements and to increase our soil quality, we use degraded soils to get the lowest readings and forest soil analysis for the highest. Farming is more fun with microBIOMETER®”, said Marcelo.