GROWTH AND YIELD RESPONSE OF THYME (THYMUS VULGARIS L.) TO SOURCES OF NITROGEN FERTILIZER

Abstract

The response of thyme (Thymus vulgaris L.) lo sources of nitrogen (N) fertilizer application was studied in field experiments conducted in 1992 and 1993. Thyme plants were grown in plots consisting of 3 rows 2.1 m long with 40 cm between rows. In 1992, thyme plants were fertilized with N at a rate of 115 kg. ha4 using N-source treatments of ammonium nitrate (35% N), ammonium sulfate (21% N), and urea (45% N). One treatment was applied with cow manure (2% N) at a rate of 230 kg N. ha '. A control plot (no N) was included as a treatment. In 1993, the same N fertilizer sources were used but N was applied at a rate of 100 kg. ha' for inorganic fertilizers and 200 kg. ha' for organic (cow manure) fertilizer. In both experiments phosphorus (P) and potassium (K) were applied at a rate similar to the P and K content of cow manure equivalent to 50 and 190 kg. ha in 1992 and 44 and 166 kg.ha' in 1993, respectively. In 1992, results indicated no significant differences in plant height, plant fresh yield and total dry matter yield among nitrogen fertilizer sources and the control. Results obtained in 1993 showed that urea and cow manure were superior to ammonium nilrate and the control in terms of total plant fresh yield. Plants fertilized with urea and cow manure produced total fresh yields of 7.5 and 7.2 t. ha ', respectively. Lowest plant fresh yield of 5.1 t ha ' was obtained from plots applied with ammonium nitrate. No significant differences in plant height were observed between treatments. It appears that urea and cow manure are the best sources of N fertilizer for thyme production in the Virgin Islands.