Data collected from 1968 through 1997 showed a globally synchronous annual increase in soil acidity during the period June through August which was highly correlated with progressively decreasing geomagnetic field strength despite periodic local alterations in electromagnetic activity at the planetary boundary layer. Monthly determinations of soil pH for periods of one or more years at sites in Australia, South America, North America, Scotland, and Germany showed pH values to be consistently and significantly correlated with the monthly average geomagnetic field strength and the auroral electrojet values recorded during the time period covered by the data. Unweighed simple and multiple 2631 ORDER REPRINTS least squares linear regressions of soil pH on geomagnetic D, H, and Z, and the auroral electrojet gave r 2 and p values as high as r 2 ¼ 0:9997; p ¼ 0:0000: These relationships were subject to modifications in soil pH by telluric currents and electromagnetic events, such as thunderstorms and accompanying acid rain, occurring at the planetary boundary layer. Short-term variations in electrical conductivity of soil, in situ plant-available soil moisture, availability of soil mineral nutrient elements for plant uptake, soil pH, and the pH of fresh and stored samples of soil diluted 1:5 in water, rainwater, and other solutions, and Rn levels in soil and air were highly correlated with ambient telluric currents and with atmospheric electrical discharges. Decreasing soil pH values were consistently associated with decreased availability of soil mineral nutrients for plant uptake, lower foliar mineral element content in growing plants, and reduced health status, fertility, and productivity of herbivores. Rising pH values were accompanied by increases in available soil mineral nutrient elements and improvements in plant and animal health and productivity.

Wasting diseases of nutritional origin in domestic livestock are infrequently seen under systems of modern management. They are seen, however, in animals grazed under extensive management systems, particularly in cattle maintained solely on tropical forages grown on low-fertility acidic soils. Secadera is one of the wasting diseases which occur in the South American tropics1,2,3,4. This report, which further characterizes the disease and its treatment, is based on research conducted in the oxisol savannas of the Altillanura, the least fertile area of the Llanos Orientales (Eastern Plains) of Colombia.