Does anyone happen to know what the optimal NPK ratio is for avocado trees? I know there's several fertilizers on the market for both citrus and avocado trees, but I suspect that avocados don't have exactly the same NPK requirements.

If it matters, my tree is roughly 10 years old, but I also have one that's about 3 years.

Phillip

Fertilizer application of avocadoes cannot be simplified into something like a 5-1-3 ratio, because most avocadoes are planted inground.

In a way, inground planting can be simplified to just apply acidifying nitrogen fertilizers and solve 95% of your problems if you have alkaline soils. So why make it more complex?

Typically other common problems are salt concentrations and zinc deficiencies.

But here is a very good CRFG Orange County article for you to read, and it is all about fertilization of inground avocado trees in Southern California:

http://home.att.net/~oc_crfg/Avocado_Fertilization.htm

Avocadoes typically loses significantly more nutrients in the shedding of their leaves than you harvest fruits from them. Further, the avocado fruits, like bananas, have also high K content, aside from the expected oil content.

Based on optimal leaf analysis, my first shot for a simplified ratio would be an 8-1-8 fertilizer for Southern California. Nitrogen should preferably be the acidifying type, and make sure to have minors such as Iron and Zinc.

The ratio is somewhat between that of citrus, 5-1-3, and bananas, 3-1-6. So avocado at 8-1-8 would be a good start.

We could improve the accuracy of the ratio if we are able to gather the typical yield, average dry matter accumulation, leaf nutrient content analyses of shedded leaves from the typical area. In other words, if we can run a mass balance nutrient analysis of avocado plants during its typical season, we can deduce what and how much fertilizer we should apply at steady state annual basis, and calculate more accurately what the ratios should be. For now, based on certain assumptions about the available data, it is 8-1-8 at this point but I am open to recalculate them for you if you provide me the data.

Yes, the cheapest are sometimes the best remedy. And it is ammonium sulfate. I strongly recommend that you increase potassium too, plus minors such as Iron and zinc, after analyzing the CRFG article.

Benny and I bought KMag from Harvey and I can easily whip up an 8-1-8 fertilizer for you.

Joe:
Any thoughts on foliar feeding of avocados? I have a bunch of fish emulsion that I need to find a use for. It's in a 5-1-1 ratio.

Phillip