Quantitative attribution of major driving forces on soil organic carbon dynamics

Abstract

Soil organic carbon (SOC) storage plays a major role in the global carbon cycle and is affected by many factors including land use/management changes (e.g., biofuel production-oriented changes). However, the contributions of various factors to SOC changes are not well understood and quantified. This study was designed to investigate the impacts of changing farming practices, initial SOC levels, and biological enhancement of grain production on SOC dynamics and to attribute the relative contributions of major driving forces (CO 2 enrichment and farming practices) using a fractional factorial modeling design. The case study at a crop site in Iowa in the United States demonstrated that the traditional corn-soybean (CS) rotation could still accumulate SOC over this century (from 4.2 to 6.8 kg C/m2 ) under the current condition;whereas the continuous-corn (CC) system might have a higher SOC sequestration potential than CS. In either case, however, residue removal could reduce the sink potential substantially. Long-term simulation results also suggested that the equilibrium SOC level may vary greatly (5.7 to 11 kg C/m 2 ) depending on cropping systems and management practices, and projected growth enhancement could make the magnitudes higher (7.8 to 13 kg C/m 2 ). Importantly, the factorial design analysis indicated that residue management had the most significant impact (contributing 49.4%) on SOC changes, followed by CO 2 Enrichment (37%), Tillage (6.2%), the combination of CO 2 Enrichment-Residue removal (5.8%), and Fertilization (1.6%). In brief, this study is valuable for understanding the major forces driving SOC dynamics of agroecosystems and informative for decision-makers when seeking the enhancement of SOC sequestration potential and sustainability of biofuel production, especially in the Corn Belt region of the United States.

Projection of corn production and stover-harvesting impacts on soil organic carbon dynamics in the U.S. Temperate Prairies

“…4 ). This finding agreed with previous studies that showed soil with high SOC levels may tend to release carbon 10 37 because SOC tends to progress toward its equilibrium level which depends on the land use and management practices applied for a given site with a given climate condition 38 39 . Land-use change could alter the equilibrium level, and thus extensive stover harvesting in high SOC areas (vulnerable areas) would likely result in substantial release of carbon.…”

“…For proper projection of plant growth and grain production, the EDCM model also took into account the enriched CO 2 effects 66 and the biological enhancement of grain production owing to gene technology, which can be found in our previous national-scale assessment 2 38 . Specifically, the corn yield has experienced continuous increase in the past century and will also increase but with a much lower rate for the coming decades 2 38 . The auto-fertilization function of the model based on N stress was implemented to ensure nitrogen content would not be a limiting factor of crop growth in this study.…”

A system approach to conservation agriculture

“…No-till without mulch cover drastically reduces crop yields in semiarid regions (Rusinamhodzi et al 2011), strongly reduces the C sink potential (Wu et al 2015), and decreases the SOC pool (Blanco-Canqui 2013).…”

Spatially distributed modeling of soil organic carbon across China with improved accuracy

“…Accounting for about 62% of global soil carbon, soil organic carbon (SOC) is an important component that affects physical, chemical, and biological processes in soils [ Lal , ; Fang et al ., ; Wu et al ., ], and a key variable for global and regional numerical weather prediction models (NWPMs) and earth system models (ESMs) [ Batjes , ; Li et al ., ; Todd‐Brown et al ., ; DeBrogniez et al ., ]. As NWPMs and ESMs have become more sophisticated, there has been growing demand for more detailed information of SOC levels and spatial variations across geographic areas [ Sanchez et al ., ; Shangguan et al ., ], which can contribute to more accurate estimations of SOC stock [ Meersmans et al ., ; Yang et al ., ] and to improve simulations of climate and earth system models [ Shi et al ., ; De Lannoy et al ., ].…”