Monday, June 21, 2010

Tropical Agroecosystems

Tropical Agroecosystems: These habitats are misunderstood by the temperate zones, mismanaged by the tropics. Janzen 1973. Science.

What tropical countries so rarely grasp is the fact that agriculture in the temperate zone countries evolved (and is still evolving) from short-term exploitation to sustained-yield agriculture while operating off a much larger natural capital than the tropical countries possess. rather than technological environment is at fault...(because of side-by-side comparisons)

The plea for technological advance gives the scientific community a perfect excuse to continue their reductionist and esoteric approaches rather than to put their efforts into the far more frustrating task of generating sustained-yield tropical agroecosystems...

...tropical people are no more interested in spending all their waking hours picking beetles of bean bushes and transplanting rice by hand than they are. High-yield tropical agriculture requires immense amounts of very accurate hand care or tremendous amounts of fossil fuel, or both...

Most of the lowland tropics would be classified as marginal farmland...there is no biological reason that the capacity to support human life should be evenly distributed over the earth's surface, nor why is should be correlated with the primary productivity of natural ecosystems or with the biomass (standing crop) of these ecosystems.

If one wishes a high yield from a particular site, year-0round warmth necessitates complex fallow systems to deal with the weeds and insects. However, it is possible that over large areas, a much lower yield per acre in fields under continuous cultivation could produce the same average yield per acre as fallow systems.

The complex biological systems of the tropical lowlands are very easily perturbed and cannot be easily reconstituted from roadside and woodlot plants and animals, as could many North American habitats.
A great variety of horticultural practices and strains of common tropical food plants have accumulated over the centuries. They are closely adjusted to local farming conditions and coevolved with the other dietary resources of the area. When high-yield hybrids are introduced, the local strains and practices are quickly abandoned. This later lead to (i) expensive and complex programs to reevolve these strains when adjusting hybrid monocultures to sustained yield tropical agriculture, (ii) increased dependence on pesticides and complex breeding programs to keep abreast of the pest problem in single-strain monocultures, and (iii) increased imbalance in the distribution of wealth among farmers.

Tropical insects appear to develop resistance to pesticides much quicker than temperate insects.

Argues that population has increased as a result of increased cash cropping, which rewards larger families and eliminates the feedback associated with subsistence agriculture.

Well-meaning persons are constantly injecting fragments of temperate zone agricultural technology into the tropics without realizing that much of the value of these fragments is intrinsic not to the technology, but rather to the society in which that technology evolved...That the tropical country "cannot resist" these gratuities is hardly justification for giving them. [as a consequence of "development"] the land deteriorates, deserts spread or become more barren, and a greater number of people end up worse off than they were before development of the area took place.

When an experiment station is centered around a major food crop, such as rice or maize, the goal becomes one of maximizing production per acre rather than per unit of resource spent...

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