I would contact the nursery you bought it from. If you cannot get help there you could always try your cooperative extension. There are wonderfull organic fertilizers at Walmart, Home Depot, Lowe's or try your local nursery. Tell them you are looking for organic fertilizer for your Papaya. If you have not got info on how to grow it you could ask there, and get the info on the best organic fertilizer. Kill two birds with one stone. Good luck! You should post whatever you find out just in case someone out there has the same question.
Andrew

I got it at the local farmer's market. I suppose I could ask next week what the man who grew them uses.

If you don't want to wai you should try a nursery. You may get a whole bunch of info that you never thought of asking for.

Papaya plants are relatively short lived so you want to get as much out of them in the time you have. They grow well with frequent applications of small amounts of fertilizer. Organic fertlizers are great for that. Any all around organic fertilizer with micronutrients should be fine. Even if it does have micronutrients you could spray every few weeks or so with micronutrients.

If your soil is sandy and has very good drainage you should water it frequently especially in hot or dry weather. If it the soil is more loamy and retains moisture you could probably go a few days without water. I would recommend mulching it either way.

A big problem you might face is that your plant might end up to be male. If it is your only papaya plant and it is a male you will probably never get fruit. There are some records of males changing sex but I wouldn't count on that for fruit. If its a female and there are no males around you probably will not get any fruit either. Your best bet are the hermaphrodite papaya plants. You could always buy a pack of seeds from aloha seeds and be guaranteed 66% hermaphrodite and 33% female. Then you cull the females once they bloom and only leave the hermaphrodite plants.

It is supposed to be a hermaphrodite plant, a Mexican papaya.

How long do they usually live out here?

It's not guaranteed to be a hermaphrodite if it was grown from seed.

They are usually productive for 3-4 years then you cut them down.

Papaya's grown in S. Florida seem to last a few years and then go into decline. Fruit production severely drops. I think there is some virus that causes the decline. Not sure what would happen in another environment where the virus may not exist.

The viruses do have an effect on the lifespan but the papaya plant is not very productive over a long term anyways. From what i've read regardless of the area you should replace them around 4 years. I've seen plants older than with fruit but they were too tall and had only a few fruit compared to what a younger plant has. Since seeds are cheap and the plant is so fast growing I wouldn't waste my time keeping older trees alive.