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livingontheland - Re: [Livingontheland] Wheat is the new oil: Nutrient Cycling

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Chronological Thread  
  • From: Harvey Ussery <huboxwood@earthlink.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: Re: [Livingontheland] Wheat is the new oil: Nutrient Cycling
  • Date: Mon, 31 Jul 2006 15:44:38 +0000

Perhaps I missed part of the conversation but if any part of the crop leaves
the land it was grown on and the manure and urine that results from its use
does not return, there will be a net loss of nutrients.

Not so fast, Phil. Don't forget that *sunlight* is also being added on the plus side of the equation. As long as the nutrients exported (farm produce) do not exceed the addition to fertility made possible by sunlight, agriculture is sustainable.

Nitrogen can be
compensated by the planting on nitrogen-fixing crops but the other mineral
nutrients are lost to the local system. They must be returned via some form
of fertilizer.

Phil

Again, it's not quite that simple. Another possibility is to "mine" minerals out of the deep subsoil using extremely deep-rooted fertility crops. You mentioned nitrogen-fixing crops, but alfalfa, for example, not only fixes nitrogen, but is deep-rooted and brings up minerals from the depths as well. Comfrey puts down roots 8-10 ft deep, bringing up minerals that would otherwise never be available to more shallow-rooted crops. Can't substantiate this, but I have read--can give you the ref if you like--that most decent agricultural soils have enough mineral content in the deep subsoil to support 100,000 years of agriculture, if sanely farmed.

~Harvey

--
Harvey in northern Va
www.themodernhomestead.us




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