Question: asking about fertilizer doses for arecanut. 
Answer: please use the recommended doses for coconut- urea- 220 gram, super 250 gram, potash 230 gram and borax 50 gram per plant  in two equal split dose once in the month of october/november and once in the month of march/april in ring method 15-20 cm depth, 1 meter away from the plant. if you notice any kind of fungal disease then use hexaconazole 10ml/liter or blitox 50 3 gram/liter of water, apply near the root zone and also spray in the affected plant part also.