Message-ID: <199610090244.WAA24344@purple> Date: Tue, 8 Oct 1996 22:44:16 -0400 From: Elin Whitney-Smith <mailto:elin@TMN.COM> Subject: Re: Sustainability & soil mineral depletion To: Multiple recipients of list DEVEL-L <mailto:DEVEL-L@AMERICAN.EDU>
Many small scale horticulturalists burn off the "natural crop" and plant their until the combination of soil depletion and weeds kill off their crop then they go on to clear and burn another place. In areas of small population this allows the old plot to revive for a number of years until the group returns. This is obviously difficult when populations are large. It also leads to deforestation.I believe, (this is out of my field) in much of the orient people make heavy use of manure and night soil (human manure) it returns a lot of nutrition.
elin Elin Whitney-Smith mailto:elin@tmn.com http://www.well.com/user/elin
>Tom Hodges mentioned an Andean cropping system in operation for 1500 years
>and Stanley Chin mentioned intensive Chinese agriculture. Soil tilth and
>fertility are maintained in these systems through cultivation and organic
>inputs--but what about mineral content?
>
>Some people in the US (esp. in the health food industry) are making much of
>the fact that for instance commercially produced spinach contains much less
>iron today than it did 50 years ago. Supposedly many foods show similar
>declines in mineral nutrient value. Is this a function of agricultural
>practices that destroy topsoil or, more broadly, of continuous cultivation in
>an area (or instrumental use of data which actually show sonmething else for
>marketing purposes). Does small scale intensive & "sustainable" agriculture
>replenish the trace minerals in soil, or do foods in such systems end up
>showing similar depletions?
>
>Don Osborn mailto:osborndo@pilot.msu.edu don.osborn@ssc.msu.edu
>
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