Modelling climate, CO₂ and management impacts on soil carbon in semi-arid agroecosystems

• Published in: Plant and soil 1996-01, Vol.187 (2), p.351-365
• Main Authors: Paustian, Keith, Elliott, Edward T., Peterson, Gary A., Killian, Kendrick
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agricultural management; Agricultural soils; Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Climate change; Climatology, meteorology; Crop management; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities. Techniques. Climatology. Meteorology. Climatic models of plant production; Grassland soils; Modeling; Organic matter; Organic soils; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plains; Soil organic matter; Soil science; STABILIZED - FORMATION AND TURNOVER; Wheat soils
• ISSN: 0032-079X; 1573-5036

In agroecosystems, there is likely to be a strong interaction between global change and management that will determine whether soil will be a source or sink for atmospheric C. We conducted a simulation study of changes in soil C as a function of climate and CO₂ change, for a suite of different management systems, at four locations representing a climate sequence in the central Great Plains of the US. Climate, CO₂ and management interactions were analyzed for three agroecosystems: a conventional winter wheat-summer fallow rotation, a wheat-corn-fallow rotation and continuous cropping with wheat. Model analyses included soil C responses to changes in the amount and distribution of precipitation and responses to changes in temperature, precipitation and CO₂ as projected by a general circulation model for a 2×CO₂ scenario. Overall, differences between management systems at all the sites were greater than those induced by perturbations of climate and/or CO₂. Crop residue production was increased by CO₂ enrichment and by a changed climate. Where the frequency of summer fallowing was reduced (wheat-corn-fallow) or eliminated (continuous wheat), soil C increased under all conditions, particularly with increased (640 µL L⁻¹) CO₂. For wheat-fallow management, the model predicted declines in soil C under both ambient conditions and with climate change alone. Increased CO₂ with wheat-fallow management yielded small gains in soil C at three of the sites and reduced losses at the fourth site. Our results illustrate the importance of considering the role of management in determining potential responses of agroecosystems to global change. Changes in climate will determine changes in management as farmers strive to maximize profitability. Therefore, changes in soil C may be a complex function of climate driving management and management driving soil C levels and not be a simple direct effect of either climate or management.