Potential effect of no-till management on carbon in the agricultural soils of the former Soviet Union

Abstract

Agricultural soils act as both a source and a sink for atmospheric carbon. Since the onset of cultivation, the 211.5 million ha of agricultural soils in the former Soviet Union (FSU) have lost 10.2 Gt of carbon. No-till management represents a promising option to increase the amount of carbon sequestered in the agricultural soil of the FSU. No-till management reduces erosion and sequesters additional carbon in the soil by lowering the soil temperature and raising soil moisture. To determine the carbon sequestered under no-till management, a data base containing precultivation estimates of soil carbon for the seven major classes of soil found in the agricultural areas of the FSU was used to establish an equilibrium carbon content for each soil. Other published data provided a method to quantify the change in soil carbon brought about by converting to no-till management. Soils suitable for no-till management were analyzed and estimates of changes in carbon storage were made. No-till management is not suitable in areas where crop production is limited by cold, wet soils. Based on the results of a geographic information system analysis using maps of climatic factors and soil characteristics, 181 million ha in the FSU were identified as climatically suitable for no-till management (almost 86% of all agricultural land). Complete conversion of all climatically suitable land to no-till management would sequester 3.3 Gt of carbon. This represents a 10% increase in carbon in the agricultural soils of the FSU. This estimated accumulation of carbon is associated with a new soil carbon equilibrium condition. Accumulation of carbon in the soil produced by a conversion from conventional to no-till management is expected to take at least 10 years. The carbon accumulation produced by conversion to no-till management is not a continuing process; once a new no-till equilibrium condition has been reached, additional quantities of atmospheric carbon will not be sequestered in agricultural soils through continued no-till management.