Edmund Leach's study of the Kachin in Highland Burma in the late 1930s

(From Wilder and King)

In this time he paid some attention to their ecology as a limiting but not a determining factor of their social and political order. He (1954) argued that in general 'hill peoples can only be expected to yield a surplus under exceptional conditions of low population density and specially favourable terrain'. Among the Kachin, Leach distinguished three kinds of upland agriculture (taungya is the Burmese term for hill field):

Monsoon taungya

Firstly (slash and burn?) the vegetation is cleared, left to desiccate during the dry season and then burned. The burned debris provided an ash fertiliser of phosphates and potassium. The ground was dibbled and drilled among the ash and sown with a variety of crops , principally hill rice, with maize, millet and buckwheat, and in this region the opium poppy as a cash crop. Usually after a year's cultivation, the area was abandoned and allowed to lie fallow and recover (usu. for 12-15 years). Gradually secondary forest established itself, then it was farmed again. Leach says that if this cycle was followed 'then there is no deforestation and negligible soil loss'. This is an extensive agricultural system because at any one time there are substantial tracts of fallow land in various stages of regrowth as the fields are used in rotation. Leach notes that Kachin villages were usually small in size, scattered and close to their fields. Shifting cultivation therefore might be put under pressure with population growth. A shortening of the fallow period, esp on hill slopes prone to erosion, might not permit the land to recover sufficiently and the vegetation to provide cover to prevent soil leaching and to yield sufficient amounts of ash fertiliser when burned.

Grassland taungya

In these regions of Burma described by Leach, the climate has less considerably rainfall than the areas which receive monsoons, so instead of forests the land is covered by pine stands, scrub and grasslands. This environments made for difficulties in ensuring sufficient rain and heat for hill rice. Beans were a favoured crop on cleared grasslands, followed by various other crops such as maize, buckwheat, millet, wheat and barley, planted in rotation on the same patch of land. The fields were then left to revert to grasslands. The poorer prospects for food crops also resulted in the cultivation of cash crops such as tea and the opium poppy.

Irrigated rice terraces

These were constructed in areas 'when local population densities are great enough to create a serious shortage of land' and where communities were relatively fixed, often for military and political reasons to control trade routes. Nevertheless, these terraces required considerable effort and energy to construct and maintain, and wherever possible the Kachin preferred to practise shifting cultivation.