throughout large parts of sub-Saharan Africa. South America and Southeast Asia are also regions where numerous intensive horticulturalists were once located. Today, however, few remain. Most of these are found in parts of sub-Saharan Africa, and perhaps in some portions of South America and Southeast Asia.
Like simple horticulturalists, intensive horticulturalists are dependent upon cultivated garden products for the bulk of their food supply, and they cultivate by the slash-and-burn method. Some of them keep domesticated animals, whereas others hunt or fish to obtain their supply of meat. Yet intensive horticulturalists differ in several significant ways from simple horticulturalists. One principal difference involves the length of time that land is allowed to remain fallow. Simple horticulturalists generally permit the land to lie fallow for 20 or 30 years before using it again. Intensive horticulturalists, by contrast, shorten the fallow period to perhaps as little as 5 to 10 years, thus cropping a given plot of land more frequently. Some intensive horticulturalists have reduced the length of the follow period even further, occasionally to the point of cultivating land almost continuously. Ancient Hawaii, for example, fell into this category. To compensate for the decrease in soil fertility that accompanies more frequent cropping, intensive horticulturalists further fertilize the soil
by adding such things as humus or animal manure.
The shortening of the fallow period has the effect of eventually converting thick forest growth to bush. Land that has been cleared of bush must be prepared for cultivation in a way that is unnecessary for land cleared of forest. Thus, many intensive horticulturalists have invented or adopted hoes for the purpose of properly preparing land for cultivation. As Boserup explains (1965:24):