Verdure: How much nitrogen does that zoysiagrass need?
Zoysiagrass’s slow establishment prompted researchers to investigate the effects of nitrogen rate and soil topdressing on its establishment from sprigs.
Beth Guertal, Ph.D.
Zoysiagrass is often considered for use because of its shade tolerance, winter hardiness (compared with other warm-season grasses) and overall durability. However, as a vegetatively propagated grass, it is slow to establish, and methods to get the grass established quickly are always of interest.
So, in 2001, turfgrass researchers at the University of Arkansas examined two factors and their effects on zoysiagrass establishment from sprigs. Those factors were nitrogen rate and the use of soil topdressing.
The research was carried out at two sites in Arkansas. Sprigs of Meyer zoysiagrass (a Z. japonica variety) were disked into the soil at a sprigging rate of 3 bushels/1,000 square feet (18 cubic meters/hectare), rolled, and then either topdressed with 0.4 inch (1 cm) of native soil or not. Sprigged plots (with and without the soil topdressing) were then split into fifths, and nitrogen was applied at rates of 0, 0.25, 0.5, 0.75 or 1 pound nitrogen/1,000 square feet/month (0, 1.25, 2.5, 3.75 or 5.0 grams nitrogen/square meter/month). The nitrogen source was ag-grade urea.
This study was a split-plot design of topdressing (native soil or none) and nitrogen rate (five rates), with four replications of each treatment combination. Collected data included percent cover, which was taken each month by using a grid to rate coverage in each plot. Also, at 120 days after sprigging, leaf tissue was harvested, and nutrient content was determined.
At 120 days after sprigging, zoysiagrass cover was 80% to 90% at both locations. Early-season establishment differed by location: The site with cooler soil temperatures at sprigging (75.2 F; 24 C) had slower percent cover than the site with warmer (87.8 F; 31 C) soil temperatures at sprigging.
Adding the soil topdressing significantly increased percent cover, with 10% to 15% more cover at 120 days when soil was topdressed across the sprigs. This improved cover was thought to result from applying native soil topdressing, which reduced sprig dessication and, ultimately, sprig mortality.
Did the addition of nitrogen improve zoysiagrass establishment?
At one location, there was a slight effect. As nitrogen rate increased from 0 to 0.75 or 1 pound nitrogen/1,000 square feet/month, percent cover improved slightly. This effect was observed at 60, 90 and 120 days after sprigging. The effect was slight, with a typical increase of around 10% to 15% cover as the increasing rates of nitrogen were added.
The second site, however, never showed any benefit from applying nitrogen fertilizer, and percent cover was unaffected by the addition of nitrogen. Regardless of treatment, the nitrogen level in harvested leaf tissue was normal, ranging from 2% to 3%, and responding little to nitrogen fertilization.
Topdressing with soil had the most positive impact on establishment of sprigged Meyer zoysiagrass, while higher rates of nitrogen fertilization (> 0.75 pound nitrogen/1,000 square feet/month) had little or no impact on zoysiagrass establishment. The authors note that other mulches for establishment of zoysiagrass should be explored, as little information about those techniques exists. Their work does demonstrate that Meyer zoysiagrass was not responsive to high rates of nitrogen and that applying nitrogen did not speed up establishment.
Source: Richardson, M.D., and J.W. Boyd. 2001. Establishing Zoysia japonica from sprigs: Effects of topdressing and nitrogen fertility. HortScience 36:377-379.
Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn University in Auburn, Ala., and president-elect of the Crop Science Society of America. She is a 20-year member of GCSAA.