Fertilization and defoliation drive the structure and productivity of Kikuyu grass Cenchrus clandestinus (Hochst. ex Chiov.) Morrone

Forage management practices, such as defoliation intensity and fertilization, have the potential to modify forage structure and productivity, thereby enhancing the sustainability of forage-based systems. This study examined how defoliation intensity (residual height, RH) and fertilization affect the growth and structure of Kikuyu grass (Cenchrus clandestinus) in the Colombian highlands. The experiment design was a split-plot with three blocks. Residual height (6 or 12 cm) was the main plot, fertilization level (control, medium, and high) was the subplot, and time was a continuous factor (accumulated days of the test). Kikuyu grass plots were defoliated at a five-leaf stage for 14 months. The following variables were measured: interval between defoliation (IBD), leaf length (LL), the number of dead leaves (NDL), undisturbed plant height (UPH), tiller density (TD), quantity (QST) and length (LST) of secondary tillers, daily growth rate (DGR), leaf area index (LAI), and plant composition (leaves, stems, and dead material). Fertilization reduced TD, QST, dead material and leafiness when Kikuyu grass was cut at 6 cm but not 12 cm. Plants required a longer regrowth period (+8 d) to reach five leaves, had fewer NDL (-0.2) and shorter LL (-1.5 cm), but grew faster (+19%) and had more stems and a lower (-46%) leaf-stem ratio when cutting at 6 cm compared to 12 cm. Fertilization reduced defoliation interval (-2.4 days) and increased UPH (+4.7 cm) and DGR (+13 kg DM per day). In conclusion, defoliation of Kikuyu grass at 12 cm, combined with nitrogen applications (274 and 462 kg N ha-1 per year), produces leafy plants and reduces defoliation intervals.