By Jeff Danner Jeff has worked in both the chemical and biotech industries and is the veteran of thousands of science debates at cocktail parties and holiday dinners across the nation. In his Common Science blog, Jeff aims to make technological and scientific concepts accessible to all.

Chapelboro 2050 Part IV: The Good Dirt

By Jeff Danner Posted February 6, 2012 at 11:32 am

This is the final installment of a four-part series on changes I expect to see in the Chapelboro by 2050 as a result of reduced resource availability.  To start at the beginning check out “Life on Two Wheels”, “A Farewell to Lawns”, and “Get into the Zone”.  This week I’ll get to the root of the local food movement, dirt.  I touched on some of these same issues in a post last year post called “Advice for Chapelboro from George Washington” but want to expand on them here and focus specifically steps we need to optimize local food production in 2050.
 
Soil is made up primarily of rock particles, decaying organic matter, and water.  The water helps to dissolve minerals and other compounds from the rock and organic matter to make them available for plants.  Plants grow by extracting carbon dioxide from the air via photosynthesis and absorbing water and nutrients from the soil.  So every time you remove a plant from the ground the soil is depleted by the amount of nutrients contained in that plant.
 
Sustaining the vitality of soil is achieved by maintaining a sufficient amount of decaying organic matter by adding compost and maintaining nutrient levels by adding fertilizer.  Generally speaking this is a job we humans are doing very poorly.  The amount of compost or manure needed to maintain the proper level of organic matter is significant and therefore expensive which causes most farmers to skimp.  Further our approach to fertilizing the soil is, to be generous, woefully incomplete.
 
The nutrients which plants need in the highest volumes are nitrogen, phosphorous and potassium.  When you purchase a fertilizer at the store they the bag shows the amounts of these minerals as the N-P-K ratio (note K is the atomic symbol for potassium).  If you start with a soil which is in fairly good condition and start to add N-P-K fertilizer, at first yields jump in a seemingly miraculous way.  During the 1960’s and 1970’s the provision of N-P-K fertilizers to places like sub-Saharan Africa and India led to dramatic increases in food production which were dubbed the “Green Revolution”.  The Green Revolution allowed farmers in East Africa to raise corn production in some areas from 15 to 50 bushels per acre, at least for a while.
 
The increase in food supply staved off starvation and led to an increase in population as more people had children and more of those children survived.  Then things started to go awry.  As time when on more and more fertilizer was required to maintain yields.  The problem stemmed from not replenishing the organic matter in the soil with compost and or manure.  When the organic content of the soil drops the dissolved minerals and nutrients become less available to the plants.
 
The second problem was the deficiency of the fertilizer.  Plants extract many more minerals from the ground than just nitrogen, phosphorous and potassium.  The second tier of minerals for plants includes boron, copper, manganese, molybdenum, zinc, iodine, and selenium.  These second tier minerals can generally be maintained by the addition of compost or manure.  Most farmer is developing nations did not have access to sufficient compost or manure to keep up.  Beyond the second tier, plants extract minute, but vital, amounts of 60 or 70 additional minerals from the ground.  In many cases we don’t know the exact function of these minerals but we can see the impact of their absence.  Plants grown in soil without these trace minerals display stunted growth, malformed structures, and reduced resistance to disease.  The opposite effect can be seen following volcanic eruptions when the falling ash repopulates the soil with these trace minerals and plant growth becomes especially vigorous.
 
In 2050 we want the soil in the Chapelboro area to be in peak condition to allow us to grow a high volume and wide variety of nutritious local foods.  To achieve this we need to look at both losses and additions to the soil to make sure the levels of organic matter and major and minor nutrients are sustained for the long term.
 
Losses from soil occur from the following:

  • Harvesting and removal of plants
  • Erosion from wind and water (primarily water)
  • The intentional removal of top soil, usually from new housing developments
  • The collection and removal of organic matter like leaves and grass which would otherwise have decomposed and become part of the soil

 
Additions to the soil include:

  • The removal of nitrogen from the air by nitrogen fixing plants
  • The addition of organic matter through compost or manure
  • The addition of minerals via fertilizer

 
Much of our public policy in Chapelboro is in line with managing our soils well but there could be some improvements.  I would change the development rules for housing developments to prevent the removal of top soil from the site.  Many new developments in the area start out with just a thin layer of sod on bare clay after all the top soil has been driven away.  I like that the Orange County sells class A compost but think suggest that we find a way to provide this to local  farmers at little or no cost.  This may result in slightly higher taxes for non-farmers but would be well worth the investment in local foods.
 
Where I think we may be able to make the greatest strides is in management of trace minerals which tend to be the most neglected part of the equation.   Since ocean water has a complete array of dissolved minerals, adding seaweed to compost makes a great addition.  The other approach to sustaining the trace minerals in our soils, and the one I believe has the most potential, is through the addition of rock dusts.  This should roughly simulate the well-known benefits of having volcanic ash fall on the ground.  Check out Remineralize the Earth for more details.
 
North Carolina is rather well positioned to become a leader in next-generation fertilizers which can provide the full array of components we need to maintain soil productivity.  We have a significant supply of manure from pig and chicken operations, have significant coastline to allow for seaweed farming, and from the Piedmont through the Appalachians we have a wide variety of rock strata which could be quarried and ground. 
 
I hope you have enjoyed this four-part Chapelboro 2050 series.  Next week I’ll get back to delving into new science and technology issues.  Look for updates on global warming and fracking.
 
Have a comment or question?  Log in below or send me an e-mail to commonscience@chapelboro.com.

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