Transformation from natural to wheat ecosystems enhances fine roots production and soil organic carbon input in an arid region

Abstract

In arid regions, fine roots turnover contributes directly to soil carbon and nutrient cycling. However, less information is available on how increasing agricultural activities influence those dynamics. Fine roots biomass, production, and turnover rate were measured by sequential soil cores based on the maximum–minimum method in the 0–60 cm soil layer in three agricultural ecosystems and three natural ecosystems. Most (87% in agricultural and 75% in natural ecosystems) fine roots were distributed in the upper 30 cm soil layer. Mean annual fine roots production and turnover were 457% and 464% greater in agricultural than in natural ecosystems. Soil organic carbon input by fine roots decomposition was 91 g m−2 yr−1 in agricultural and 11 g m−2 yr−1 in natural ecosystems. Both fine roots biomass and fine roots production were significantly higher for two winter wheat (Triticum aestivum) ecosystems from May to October, 2010. Soil pH ranged from 8.2 to 9.4. Soil water content in agricultural ecosystems was higher, whereas soil electrical conductivity was lower than that in natural ecosystems. pH, soil bulk density, gravimetric soil water content, and soil electrical conductivity significantly affected fine roots biomass, production, turnover, and decomposition in all ecosystems investigated. The findings increase our understanding of the soil carbon cycle after natural ecosystems are modified into agricultural ecosystems.