Effects of Three Harvest Intervals and Two Fertilizer Rates on the Yield and HCN Content of Ten Cynodon Cultivars

Abstract

Ten forage grasses (Cynodon spp.), including recent introductions, and Stargrass (C. nlemfuensis var. nlemfuensis) were grown in the central mountains of Puerto Rico to measure the effect of two fertilizer rates and three harvest intervals on the forage yield, crude protein yield and hydrocyanic acid content (HCN) for a 2-year period. Fertilizer treatments applied after each harvest consisted of 2.24 and 4.48 metric tons/ha/year of a 15-5-10 fertilizer. Significant differences occurred between fertilizer rates as to dry forage and crude protein yields. Number of harvests per year were 6, 8 and 12 for 30-, 45- and 60-day intervals, respectively. Significant differences occurred among cultivars and harvest intervals. Cynodon dactylon (PRPI 11504), C. plectostachyus (PRPI 11487) and C. nlemfuensis var. nlemfuensis (PRPI 2341) occupied most of the top yield positions at the three harvest intervals. HCN within the cultivars ranged from 0 to 333 p/m.