Sow what? Climate reviews help farmers choose.

African subsistence farmers are far likelier to leverage rainfall forecasts into better crop yields after attending workshops explaining the basis for the rain predictions, some of which include climatic events half a world away.

Anthony Patt of Boston University and his colleagues organized short workshops for a randomly chosen cross-section of subsistence growers--those who plant crops for their own consumption, not commerce--in several Zimbabwean villages. The workshops preceded planting seasons and explained the government's rain predictions, factors contributing to their uncertainty, and planting strategies that the farmers might adopt in response to the forecasts and uncertainties.

A major issue influencing the rain predictions, the workshop instructors explained, is the timing and severity of any recent El Nino, a prolonged period of warm surface waters in the west equatorial Pacific (SN: 8/17/02, p. 110).

In the Aug. 30 Proceedings of the National Academy of Sciences, Patt's group presents data from two villages for the 6-month growing season in two successive years. The first season's drought and second year's ample rains had been predicted fairly accurately.

Farmers who attended the workshops were several times more likely than others to have changed, in response to the forecasts, the timing of their planting or the crops they chose to plant. This proved especially beneficial, Part notes, when the second year's forecast indicated that these normally dry villages might reasonably gamble on planting crops, such as "long-season" maize, that need more water but hold the potential for much higher yields than the usual, shorter-season cultivar. Harvests by farmers who received workshop training were 20 percent greater in that rainier year than those of their peers who hadn't gone to the workshops.--J.R.