The Soil Biology Model of Plant Nutrition

The Soil Biology Model of Plant Nutrition

Last November I went to the 7th Annual Bionutrient Food Association Soil & Nutrition Conference in Massachusetts where as expected I got my world turned upside down. These conferences  expose you to so many ideas and personalities that you would have to be brain dead to not be over stimulated. I always need a few days to start to assimilate and understand what just happened.


At breakfast the first morning the last seat at our table was taken by a woman who introduced herself as  Dr Elaine Ingham . It was my turn going around the table to tell what my strategy was to grow the best garlic I could. I mentally patted myself on my back as I told of the tight schedule of soil testing and amendment application to provide all the nutrition my garden could need. Then Dr Ingham asked “Why in the world would you do that?” Huh? Then Dr. Ingham said that all the nutrients were already in the soil and there was no need to add fertilizers and I was probably damaging the soil and limiting my plants growth not to mention wasting money and all I needed to do was get the biology back in the soil. Dr Ingham told me to take her course and then disappeared whisked away by colleagues.


The idea that it was the health of the soil as a living system that was paramount was a totally new idea. I had heard mention of the “life in the rhizosphere” but only in passing. Why wasn’t more being said about this?


Several days later back home I was discovering Dr Ingham’s I got out my credit card and signed up. The class enrollment was for a year and classes could be taken at your own pace. There are four components to the class. Life in the soil, Compost, Compost extract and Tea, and the Microscope.


The class teaches that the bacteria and fungi are the “decomposers” that 1. that decompose plant material produceing enzymes that dissolve the parent material of the earth-the rock, sand, silt, and clay. All the nutrients necessary for the plants needs (with exception of Carbon, Oxygen, and Nitrogen which  are obtained from the atmosphere) are present in the parent material of anyplace on the earth. The mineral nutrients are internalized by the bacteria and fungi and are made available to the plants when protozoa, nematodes, micro and macro arthropods, earthworms, mammals eat the bacteria and fungi and excrete. The minerals are now in a plant available form. Using photosynthesis, the plant takes in CO2 and produces sugars that are exuded from roots to feed the bacteria and fungi in the rhizosphere. Here a symbiotic relationship exists where the bacteria and fungi provide the nutrients to the plant and the plant feeds sugars to the microbes.  Although a simplification it is the basic idea.

“Soil as defined by Hans Jenny, the Father of Soil Science.”


  1. Mineral: Sand, silt, clay, All minerals balanced,


  1. Organic Matter.


  1. Organisms.


  1. Abiotic factors. Temperature and moisture.

If your garden, field does not have these four components, its dirt, not soil.


First things first. Know what organisms are in your soil. You do this by analyzing your soil sample using a microscope. Your soil must have a minimum content of bacteria and fungi and protozoa to have an acceptable level of plant growth.


So how do I bring bacteria, fungi, protozoa, nematodes, micro and macro arthropods, worms, etc into my soil? The primary way is thru correct compost building. Compost isn’t just a way to dispose of plant material, household waste, animal waste thereby adding organic matter. The important purpose of compost is to foster the reproduction of bacteria and fungi. By using certain combinations of high nitrogen, green material, and brown material it is possible to influence the end population of bacteria and fungi. The compost is then added to the soil as an inoculant. The bacteria and fungi (with the organic matter as a food source) will then begin multiplying and providing nutrients to the plants.


Of note in the “Life in the Soil” class was the information that traditional soil tests tell you what the ratio of Ca to Mg is in your soil. It should be in the range of 7:1 depending on the type of soil you have. This ratio ensures that structure of soil will be “looser”, drainage will be enhanced and compaction lessened.


Now my soil amendment plan is to make good compost using my thermometer and microscope to monitor the growth of bacteria and fungi. To be continued.

If you’ve read this far, I urge you to visit Dr. Inghams  or