Healthy soil and sustainable growing

[Soilsecrets@aol.com]

In a message dated 12/4/2006 11:46:08 P.M. Mountain Standard Time, tradingpost@lobo.net writes:

but the photo shows about three inches of
topsoil built over 4 or 5 years. In my book that would qualify as years
totally wasted.

Paul,

 

Is it really wasted effort or time?  Well in your opinion it may be, but in my mind it's not and it's certainly not in the opinion of Kim who has worked tirelessly on this project. 

 

So let me explain what this 3 inches of humus rich top soil really means. 

 

1. To see 3 inches of humus rich top soil form in just 4 to 5 years is a daunting task even in a good climate where you don't have the high elevation intense UV burning up the organic matter of the soil.  Or where there is plentiful rainfall to produce weeds and grasses that produce organic biomass easily, thus providing an abundant pipeline of calories that the Soil Food Web can turn into Humus.  Most deserts of the world don't have that advantage and neither does this site, so producing 3 inches of top soil in such a short time is an amazing thing to see.  I've been a Soil Scientists and a Plant Ecologists for 30 years and I've only seen it on a very rare occasion.  If you recall your school days of Earth Science classes, you were once told, and accurately so,  that under good conditions it takes nature at least 100 years to grow 1 inch of top soil.    So what's wrong with 3 inches in 4 to 5 years?

 

2. What does 3 inches of humus rich top soil represent?  Well let me define for you this information as it relates directly to this site as we have quantified it. 

  -The soil on this site is not alkaline as you stated but rather it is a decomposed sandstone that is acidic. 

  -The bulk density of the soil is right at 98.3 pounds per cubic foot. 

  -The 3 inches of humus rich top soil weights 1,089,000 pounds to the acre.   

  -The humus percentage by weight of this soil is 60,000 pounds per acre in the top 3 inches.  "Humus is a conglomeration of biomolecules that are essential for healthy and productive soils" Journal of Chemical Education 2001

  -The caloric equation taking a super high quality compost with a bulk density of 90,720 calories per cubic foot and turning it into pure humus (Humification) is this: 10,000 pounds of compost = 40 pounds of humus.  Therefore in order to make one acre of 3 inch deep top soil that contains 60 thousand pounds of Humic substances (per acre 3 inches deep) you will need 15 million pounds of a super high quality compost! Most compost made in windrows will have a bulk density of about 17 - 20 pounds per cubic foot, therefore it will take about 28 thousand cubic yards of compost on a acre in order to make enough humus to make the 3 inches of humus rich topsoil such as that found on this Arizona desert organic farm.  It truly is a daunting task!

 

3. While growing grass as a nurse crop, ground cover and root-tunnel crop is an excellent idea if the site allows for it, growing grass by itself will not create a mycorrhizal environment.  If the soils did not have a indigenous grass cover that was mycorrhizal to begin with the mycorrhizae will not mysteriously appear just because you planted grass! You will need to inoculate the grass seed or soil in order to make this happen!

 

 

Fortunately most humus in the soil and on this site for sure did not come from compost, or from sheet mulching.  Furthermore it did not come from the supplemental humus provided by Soil Secrets either as Kim only added a fraction of that 60,000 pounds that now occurs on the site.  Most of it came via a process we understand to be called Carbon Sequestration, where nature creates a provision for long-term storage of carbon in the terrestrial biosphere, most found in the form of Humus and Glomalin.  

 

 I'm out of time and continue this later. 

 

Dr. Michael Martin Melendrez