Abstract

Warming of the atmosphere will increase mean annual soil temperatures. Large areas in the Northern Hemisphere could become suitable for cultivation, assuming little change in rainfall patterns. A 3 °C temperature rise is predicted to cause an overall 11% decrease in soil organic matter content to a 30-cm depth in the temperature zone, but this increase is well within the standard deviations of the data. If so, a 3 °C temperature increase in the temperate zone is predicted to increase atmospheric CO₂ content by approximately 8% over the present (1990) levels during a 50-yr period, provided no increase in biomass production occurs. Carbon/N ratios of soil organic matter are expected to narrow slightly, and total N in the soil is predicted to increase by 10% in the temperate region. However, an average increase of 568 kg ha⁻¹ above and belowground organic residue return to the soil is sufficient to offset changes in soil organic C content. No major changes in fertilization practices are predicted, because modern fertilizer rates greatly exceed weathering rates in providing nutrients to plants. Increased solubility of soil minerals is expected to be slight. Redder soil colors may result from hematite formation.

Copyright © 1990. . Copyright © 1990 by the American Society of Agronomy, Inc., Crop Science Society of America, Inc., Soil Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA