My take on the sentence is this:

In the context of the last 2,000 years of irrigation rice farming, the differences in “development (or lack of development) of villages from extensive rice farming” seen widely throughout the Asian continent needs to be carefully considered.

I used "extensive rice farming" for "粗放米作" since 粗放nogyo = extensive farming.

I think they are trying to say that extensive farming can develop or (not develop) an area and that all the factors have to be specially noted and put into consideration.

There are samples of sentences using extensive farming below and there are many other examples through the net.

http://en.wikipedia.org/wiki/Extensive_farming
Extensive farming is found in the mid-latitude sections of most continents. The nature of extensive farming means it requires less rainfall than that of intensive farming.
Just as the demand has led to the basic division of cropping and pastoral activities, these areas can also be subdivided depending on the regions rainfall, vegetation type and agricultural activity within the area and the many other parentheses related to this data.
http://www.fao.org/docrep/009/a0444e/A0444E08.htm
Traditional extensive rice-fish farming is still practiced in Niger, Senegal and Mali, where river floods and rising tides pour fingerlings into rice plots where they grow until harvest. Human intervention in this system is mainly concerned with the infrastructure and not with fish because water regulation is needed to increase rice production.

Been doing a lot of agriculture

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Note added at 1 hr (2008-01-18 15:51:57 GMT)
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I was going to say (but cut myself off) that I have been doing agriculture-related work lately...but there's always something new. Hope this helps.