Carbon dioxide fluxes over bermudagrass, native prairie, and sorghum

• Published in: Agricultural and forest meteorology Vol. 93; no. 2; pp. 121 - 139
• Main Authors: Dugas, W.A, Heuer, M.L, Mayeux, H.S
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 22-02-1999; Oxford Elsevier; New York, NY
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Bowen ratio; C4 PLANTS; CARBON CYCLE; CARBON DIOXIDE; Carbon flux; Chemical, physicochemical, biochemical and biological properties; CICLO DEL CARBONO; CO 2; CYCLE DU CARBONE; DIOXIDO DE CARBONO; DIOXYDE DE CARBONE; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities, techniques; Generalities. Techniques. Climatology. Meteorology. Climatic models of plant production; GRAMINEAS; GRAMINEE; GRASSES; Grassland; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; PLANTAS C4; PLANTE EN C4; Sequestration; Soil CO 2 flux; Soil science; Synecology; Terrestrial ecosystems; TEXAS; VAPEUR D'EAU; VAPOR DE AGUA; WATER VAPOUR; United States; North America; Texas; America; Grassland; CO 2; Carbon flux; Soil CO 2 flux; Sequestration; Bowen ratio; Monocotyledones; Cultivated field; Material flow; Cultivated soil; Sorghastrum nutans; Carbon dioxide; C4-Type; Cereal crop; Cynodon dactylon; Sorghum bicolor; Andropogon gerardii; Gramineae; Ecosystem; sequestration; Angiospermae; Chemical composition; Native species; Agroclimatology; Agroecosystem; Carbon cycle; Micrometeorology; Mass flow rate; Agrometeorology; Air ground interface; Spermatophyta; Low atmosphere; Fodder crop; PRAIRIES; GRASSLAND SOILS
• ISSN: 0168-1923; 1873-2240
• DOI: 10.1016/S0168-1923(98)00118-X

The Bowen ratio/energy balance (BREB) method was used to measure 30
min water vapor and carbon dioxide (CO
2) fluxes over three fields dominated by different C
4 grasses (bermudagrass, tallgrass native prairie, and sorghum) at the Blackland Research Center, Temple, TX. Fluxes were related to biotic and abiotic phenomena. Carbon accumulation rates calculated from BREB measurements were compared with those determined from plant biomass measurements. Thirty min CO
2 fluxes were measured continuously from 22 February to 22 November (days 53–326) in 1993 and from 3 March to 22 November (days 62–326) in 1994. Soil CO
2 fluxes were measured periodically in each field and from a bare soil. In all fields, average daily evapotranspiration varied from less than 1
mm day
−1 in March and November to about 5
mm day
−1 in June and July. The CO
2 fluxes, which were affected by leaf area, radiation, and soil water content, were near zero in each field in the fall and spring and were maximum in the summer (positive toward surface). Total annual CO
2 flux in the bermudagrass, which was sprigged (planted with grass stolons) in April 1993, was −0.4 and 2.8
kg of CO
2 m
−2 year
−1 (which are equivalent to −0.1 and 0.8
kg of carbon (C) m
−2 year
−1) in 1993 and 1994, respectively. The larger flux in the second year was due to greater bermudagrass leaf area. Corresponding annual CO
2 fluxes were 0.2 and 0.3
kg
m
−2 year
−1 (0.05 and 0.08
kg C
m
−2 year
−1) for the prairie, and 0.9 and −0.3
kg
m
−2 year
−1 (0.2 and −0.09
kg C
m
−2 year
−1) for the sorghum. Bare soil CO
2 flux was a small fraction of soil CO
2 flux from all fields, suggesting that a considerable amount of soil CO
2 flux was due to root respiration. The dry matter accumulation rate calculated for each year and field from CO
2 flux measurements was within 20% of the rate calculated from gravimetric biomass measurements. The prairie and sorghum fields were in approximate equilibrium for C storage because estimated annual CO
2 fluxes were near zero. By contrast, the bermudagrass field was a large C sink, primarily in the roots, during the second year. This substantiates other evidence that conversion from continuously cultivated cropland to grassland could create a short-term C sink.