Impact of Conservation Management Practices on Carbon Dioxide Emissions in a Semi-Arid Region.

The global conversation on climate change typically covers the three C’s: cars, coal, and cows. This overlooks an important source of greenhouse gases (GHGs), the soil also happens to be one of the best potential ways to mitigate and sequester GHGs. Row-crop agriculture accounts for about 10% of GHG production in the USA. Specifically focusing on the production of CO₂, microbial respiration is the major source of soil-derived CO₂. It has been suggested that by reducing tillage, the flux of CO₂ could be mitigated. Soil conservation management practices have been applied to agricultural soil on the Texas High Plains with the primary objective of reducing soil erosion and loss of topsoil. However, the impact of reduced tillage and cover cropping on CO₂ emissions has not been evaluated in the Texas Southern High Plains. Seventeen months of gas flux data have been collected, and cotton (Gossypium hirsutum L.) yield has been measured for the 2016 growing season. Conservation practices used include three tillage regimes: No-till with winter wheat cover, no-till winter fallow, and conventional tillage. In addition to tillage, five nitrogen fertilizer treatments are used: control (no fertilizer added), 100% pre-plant, 100% side-dressed, 40% pre-plant/60% side-dressed, and 100% pre-plant with a nitrogen stabilizer. This study is set up as a factorial, resulting in 15 unique combinations, replicated three times for a total of 45 plots. From this data, we have identified the use of no-till and split applied nitrogen fertilizer as the best management for CO₂ mitigation. This combination did not result in greater lint yield; however, in general, some lag in yield is expected when converting to no-till from a previously tilled system. In conclusion, the use of conservation management practices, no-till with a split application of nitrogen fertilizer, on the Texas High Plains can reduce CO₂ losses from soil.