Vegetated land surfaces play an important role in determining the fate of carbon in the global carbon cycle. However, our understanding of the terrestrial biosphere on a global scale is subject to considerable uncertainty, especially concerning the impacts of climatic variables on the carbon cycle. Soil is a source and also a sink of co 2 exchange and helps in carbon sequestration. Agricultural management practices influence soil water dynamics, as well as carbon cycling by changing soil CO 2 emission and uptake rates. the rate of soil co 2 emission varies for different crops and different organic amendments. the major goal of this study was to assess the impacts of the type and rate of organic amendment on soil co 2 emission in a collard greens crop grown in the southeast texas environment. thirty-six plots were developed to grow collard greens on prairie View A&M University's Research farm. three types of organic amendments (chicken manure, Dairy manure, and Milorganite), at four levels of application (0, 168, 336, and 672 kg N/ha) were used and replicated three times. Each organic amendment type was applied to nine randomly selected plots. three random plots were used as a control in each row. We measured daily soil co 2 emission for the first two weeks and every other day in a week during the experiment. We evaluated the effects of organic amendments and the application rates on soil co 2 emission for collard greens during two growing seasons. the results showed higher the application rates for each organic amendment, higher the co 2 emissions from the soil. the results also showed higher cumulative co 2 emissions for the soils amended with chicken manure and milorganite, but lowest for the soils amended with dairy manure. This field experiment and analyses help better understand the temporal and spatial variations of soil co 2 emission, and also help to develop best management practices to maximize carbon sequestration and to minimize soil co 2 emissions during the growth periods of collard greens under changing temperatures using different organic amendments, and application rates. Vegetated land surfaces play a significant role in controlling the carbon dynamics in the global carbon cycle; however, knowledge about the comprehensive role of the terrestrial biosphere on regional to global scale under changing climate is still limited 1. Greenhouse gases, including CO 2 emissions, are rapidly increasing because Earth's climate is continuously warming 2-4. The physiological processes of vegetation leaves and photosynthetic capacity, which influence carbon emission and carbon uptake, rely on daily and seasonal variations of weather parameters, and hydrologic and climatic variables (e.g., solar energy, soil and air temperatures, humidity deficits, soil moisture) 5-10. Hence, CO 2 fluxes over agricultural lands are expected to vary on daily and seasonal time scales. During the growing season, vegetation coverage reduces bare soil areas to the environment. For example, in the beginning, the soil surface used to be...

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The chemical, morphological, and mineralogical properties of two soil‐saprolite profiles from the Durham Triassic Basin were determined. The relationship between clay mineralogy and shrink‐swell activity of the soils was also determined. The parent rock from the Vertic Hapludult profile was a fine‐grained red sandstone with muscovite mica, quartz, and feldspars as the dominant primary minerals. The parent rock from the Aquic Hapludult profile was a coarse‐grained gray sandstone with feldspars, muscovite mica, and quartz as the dominant primary minerals. The argillic horizons in both profiles had cracks, slickensides, high clay contents, moderate to high coefficient of linear extensibility (COLE) values, and smectite as the dominant clay mineral. The COLE values are greatest in horizons that display evidence of shrink‐swell activity (cracks and slickensides). The COLE values do not correlate well with either fine or total clay content, which implies that factors other than fine or total clay content influence COLE values. Base saturation percentage increases abruptly below the paralithic contact requiring close examination for correct Ultisol or Alfisol placement.

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