Response of Coastal Bermudagrass Yield and Nutrient Uptake Efficiency to Nitrogen Sources

Nitrogen is an important agronomic input for bermudagrass production in the southern USA. Fertilizers that can efficiently provide N to grass pastures and hay meadows are an important issue because of increasing costs and environmental problems associated with N losses. This experiment was designed to determine the effectiveness of various N sources on ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.] production and N uptake efficiency. Nitrogen was applied at 0, 45, 90, and 135 kg ha−1 harvest−1 as urea–ammonium nitrate (UAN), urea, ammonium nitrate (AN) and ammonium sulfate (AS) on Gallime (Glossic Paleudalf) and Lilbert (Plinthic Paleudult) soils. Mixtures of S with UAN and of Ca and B with urea were also evaluated. Bermudagrass was periodically harvested and subsampled for total N analysis. At termination of the study soil samples were collected for pH and extractable NO3–N analyses. Bermudagrass yield responses to N sources were significant only in the Gallime soil. In this soil, AN and AS increased yields and resulted in greater N uptake compared to urea and UAN. Lilbert soil showed no effect of N sources on dry matter (DM) production. There was a yield response to N rates and maximum bermudagrass production was generally achieved at the 90 kg ha−1 N rate regrowth−1. Fertilizer efficiency declined as the N rate was increased. Soil acidity increased in response to N application, particularly for the AS treatments. Selection of N sources and rates should be carefully planned to avoid detrimental effects on soil acidity and, consequently, fertilizer efficiency.