Abstract
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 CO2 exchange and helps in carbon sequestration. Agricultural management practices influence soil water dynamics, as well as carbon cycling by changing soil CO2 emission and uptake rates. The rate of soil CO2 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 CO2 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 CO2 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 CO2 emission for collard greens during two growing seasons. The results showed higher the application rates for each organic amendment, higher the CO2 emissions from the soil. The results also showed higher cumulative CO2 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 CO2 emission, and also help to develop best management practices to maximize carbon sequestration and to minimize soil CO2 emissions during the growth periods of collard greens under changing temperatures using different organic amendments, and application rates.
Highlights
Vegetated land surfaces play an important role in determining the fate of carbon in the global carbon cycle
Regardless of organic amendment types and their application rates, Soil carbon dioxide CO2 (SCO2) emission spiked following the organic amendment and gradually decreased; it reached the lowest levels in three months after the start of the experiment (Fig. 3)
The observed increase in SCO2 emission in response to increasing temperature and soil moisture/rainfall indicate an increase in microbiological activities; such activities result in an increase of the soil organic carbon and carbon dioxide emission because SCO2 is mainly produced as a result of the soil microbial respiration and vegetation root respiration[48,49,50]
Summary
Vegetated land surfaces play an important role in determining the fate of carbon in the global carbon cycle. We evaluated the effects of organic amendments and the application rates on soil CO2 emission for collard greens during two growing seasons. The results showed higher cumulative CO2 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 CO2 emission, and help to develop best management practices to maximize carbon sequestration and to minimize soil CO2 emissions during the growth periods of collard greens under changing temperatures using different organic amendments, and application rates. Atmospheric CO2, one of the major greenhouse gases, which has an impact on global warming, and www.nature.com/scientificreports its variation is in response to global natural and human activities Changes in climate, such as precipitation and temperature, could alter the exchanges of these gases by altering plant activities, as well as thermal and hydrologic regimes[15]. It is important to monitor CO2 emission and uptake worldwide to achieve a sustainable environment[21,22]
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