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Title: Simulated bermudagrass production and nitrate leaching affected by ENSO, soil, and clipping frequency

Author
item WOLI, PREM - Texas A&M University
item ROUQUETTE, MONTE - Texas A&M University
item LONG, CHARLES - Texas A&M University
item Gowda, Prasanna
item PEQUENO, DIEGO - University Of Florida

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2017
Publication Date: 9/7/2017
Citation: Woli, P., Rouquette, M.F., Long, C.R., Gowda, P.H., Pequeno, D.N. 2017. Simulated bermudagrass production and nitrate leaching affected by ENSO, soil, and clipping frequency. Agronomy Journal. 109:1-13. doi:10.2134/agronj2017.05.0268.

Interpretive Summary: Coastal bermudagrass is one of the major pasture-hay grasses in the southern United States. In this modeling study using a crop growth simulation model, we evaluated the effects of clipping frequency on dry matter production and nitrate leaching under two different soils and meteorological conditions. Simulated results indicated higher clipping frequency increased dry matter production and decreased nitrate leaching, however, both at decreasing rates. Lower dry matter yields were associated with a soil with high runoff potential especially in El Nino years irrespective of clipping frequency. Nitrate leaching is predicted to be higher during El Nina years regardless of clipping frequency and soil types. Overall, clipping intervals shorter than four weeks are not beneficial from both agronomic and environmental perspectives. Additional work is required to evaluate forage quality.

Technical Abstract: Coastal bermudagrass [Cynodon dactylon (L.) Pers.] is the basis for many forage production systems in the southern United States. The agro-environmental studies on this grass, however, are limited for this region. This study, using the DSSAT crop model, assessed bermudagrass dry matter (DM) yield and N leaching responses to clipping interval, soil type, and El Niño-Southern Oscillation (ENSO) in the Pineywoods region of Texas. The response variables were simulated for various scenarios including two soil types, five clipping intervals, and 74 years of weather data. The simulation results showed a curvilinear relationship between clipping intervals and DM yields or N leaching. Bermudagrass DM yields were less; whereas N leaching was greater over a soil with high runoff potential, compared with a soil whose runoff potential was moderate. Of the three ENSO phases, El Niño was associated with the lowest DM yields and the greatest N leaching. The bermudagrass model tended to overestimate N leaching and underestimate DM yields by a larger magnitude for a longer clipping interval and for a soil with higher runoff potential and higher wilting points. Results suggested that using clipping intervals shorter than four weeks on any soil in any given year might not be beneficial from both agronomic and environmental perspectives. The findings of this study might be helpful to Coastal bermudagrass producers in this region to identify soil- and weather-specific clipping frequencies to optimize forage production while minimizing the nitrate contamination of groundwater.