The effects of NPK rates and planting rates on Lobo™ zoysiagrass establishment in the transition zone

Abstract

Zoysiagrass (Zoysia spp.) is widely used in turfgrass systems due to its exceptional tolerance to environmental stressors and reduced maintenance requirements. However, its relatively slow establishment rate, especially using vegetative propagation methods such as sprigging and plugging, limits its widespread adoption. This study evaluated the impact of planting rates and varying nitrogen (N), phosphorus (P), and potassium (K) fertilizer combinations on the establishment and performance of newly released cultivar Lobo™, a Z. japonica × Z. matrella hybrid. The experiment took place at Lake Wheeler Turfgrass Field Laboratory (Raleigh, NC) in 2024. Two planting rates (sprigs at 5 or 10 m³ ha⁻¹) were tested, supplemented with low (9 plugs/plot) and high (16 plugs/plot) plugging rates due to drought-related sprigs loss. Sixteen fertilization treatments, combining four N rates (0, 12.5, 25, and 50 kg ha⁻¹), two P rates (0 and 25 kg ha⁻¹), and two K rates (0 and 25 kg ha⁻¹), were applied weekly for the first month, then monthly. Results showed that planting rates and N rates positively influenced percent green cover. However, increasing N rate beyond 12.5 kg ha⁻¹ did not yield additional benefits, suggesting an optimal economic threshold for sod growers. Turfgrass color, indicated by normalized difference red edge, was enhanced by a higher N rate and planting rate, and was subtly increased by a higher K rate. Phosphorus rates had no significant effect on establishment or color. This study highlights the importance of optimized planting and fertilization strategies for efficient and cost-effective establishment of Lobo™ zoysiagrass.