EFFECTS OF DIFFERENT NPK FERTILIZERS AND TIME OF HARVEST ON PHYSICAL QUALITY AND ROOT YIELD OF CARROT (DAUCUS CAROTA L.) CULTIVATED IN THE “BEDIESE SOIL AND NYANKPALA SOIL SERIES” OF GHANA

Abstract

Fertilizer formulations and time of harvest are among the important factors that influences the yield and quality of vegetable crops. The use of NPK (15-15-15) fertilizer and harvesting at 80-90 days after sowing (DAS) are common practices among carrot farmers in Ghana. In this study, we investigated the effects of different NPK fertilizer formulations and time of harvest on physical quality and root yield of carrot cultivated in the “Bediese soil series” and “Nyankpala soil series” of Ghana. A 5 × 3 factorial experiment was conducted with three replications at both locations. The fertilizers [(i) 15-15-15 (ii) 23-10-5 (iii) 20-10-10 (iv) 23-10-10, at 300 kg ha-1 each and (v) control (no fertilizer)] were applied to the main plot whiles time of harvest [(i) 80 (ii) 90 and (iii) 100 DAS)] were the sub plot treatments. There was no significant (P>0.05) interaction effect of the treatments on all the parameters measured at both locations. In the “Bediese soil”, the application of 300 kg ha-1 NPK (20-10-10) fertilizer significantly (P<0.05) improved the physical quality of the roots which resulted in the highest marketable yield. Moreover, harvesting at 100 DAS also increased the physical quality of the roots and gave the highest marketable yield compared with harvesting at 80 and 90 DAS. Generally, the different fertilizers and times of harvest did not affect (P>0.05) the physical quality and yield of carrot cultivated in the “Nyankpala soil”. The study has shown that the application of 300 kg ha-1 NPK (20-10-10) fertilizer and harvesting at 100 DAS can be used to increase the yield and improve the physical quality of carrot cultivated in the “Bediese soil series” of Ghana.