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Nitrogen fertilization recommendations for South Carolina are largely based on research conducted in the Piedmont regions of South Carolina, North Carolina and Georgia. The Piedmont is characterized as having soils with high clay content. These soils generally hold more water and nutrients in the root zone, which may result in the reduced need for nitrogen fertilizers to maintain a healthy turf. Soils with a high sand content hold less water and nutrients and may require additional fertilizer inputs to maintain a healthy turf. Currently, the Agricultural Service Laboratory at Clemson University recommends no more than about 0.5 lb. N/1000sq ft /year on centipedegrass grown in fine loamy soils or clay soils and no more than 1lb.N/1000sq ft /year on centipedegrass grown in sandy, coarse-textured soils or coarse loamy textured soils. However, minimal research has been conducted on fertilization requirements of centipedegrass in soils with high sand content. The purpose of this study was to establish nitrogen fertilization guidelines for centipedegrass grown in the sandy soils of central and coastal South Carolina. |
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MATERIALS AND METHODS |
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A nitrogen fertilization study with 9 rates was conducted at four locations in South Carolina. The fertilization treatments were 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, and 2 lbs. N/1000 sq ft applied in May and July. A quick release source of N formulated in a greens grade, 16-4-8 fertilizer was used for treatments. The four locations were Columbia, Charleston, Florence and Myrtle Beach, SC. Local county agents assisted in applying the fertilizer treatments and were responsible for taking color, density and quality rating once every two weeks from May until dormancy in Columbia, Charleston and Myrtle Beach, SC. Treatments and ratings were performed by the author at the Florence, SC location. All of the sites had automatic irrigation systems and were watered to minimize wilt. The plots were mowed weekly at heights ranging from 1 to 2 inches depending on location. The experiment was conducted as a randomized complete block design with 9 treatments and four replicates. Data were averaged over five dates to determine treatment means. Data were analyzed by ANOVA and means separated at P=0.05 by the least significant difference test. Only data from the Florence location is presented in this report. |
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RESULTS AND DISCUSSION |
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A color rating of five to five and a half designates that a plot had good color for the purpose of this study. As a general trend, color increased as N rate increased (Table 1). Differences in color tended to diminish at 6 to 8 weeks after the treatments were applied (June 28 and July 11). Differences in color on a given date were detected in treatments that had ± 0.5 lb. N/1000 sq ft. Plots that had a dark green color (5.8 and above) were among the first to wilt during July and August (data not shown) ( Figure 1). All plots had 100 percent cover and there were no differences in turfgrass density among N rates. All N treatments received quality ratings that were considered good for centipedegrass due to high-density and uniformity. Plots receiving between 0.5 lb. and 0.75 lb. N/1000 sq ft per application had good to excellent quality through July 11 (Table 1.). Eight weeks after initial applications (July 11) there were no differences in turfgrass quality in plots with N rates greater than or equal to 0.75 lb./1000 sq ft. Preliminary observations suggest that plots receiving between 0.25 and 0.75 lb. N/1000 sq ft in May and July may perform best over time. These plots did not wilt between scheduled irrigation during July and August, or scalp after mowing. Although centipedegrass is a low maintenance turf, it does require N to keep the turfgrass healthy and dense. Timing seems to have played an important role in the quality of test plots. All of the plots looked good when fertilized in May and showed no detrimental effects when the average high temperature was 83º F. When treatments were applied in July when the average high temperature is 89º F, the plots with N rates greater than or equal to 1 lb. of N/1000 sq ft per application began showing signs of wilt and scalping. Turfgrass quality ratings were not taken immediately after mowing and do not reflect the poor mowing characteristics of the plots that were fertilized with greater than or equal to 1 lb. of N/1000 sq ft per application in July and August.
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