Not a lot. You will have about 5 years paying the expenses BEFORE the trees are able to produce avocados for you.
But let us play with the numbers... the Dept of Agriculture says you can grow 400 Avocado trees on a 1 acre plot.
It also says that the trees average 150 avocados per season.
Soooo.....400 x 150 =60,000 (avocados)
I can buy an Avocado in the grocery for $2.00 (sometimes $3.50 ...sometimes 1.50 depending on the season)
So since the $2.00 price is the retail price....I will guess that the wholesale price will be $1.00 (or less...probably less)
So $1.00 x 60,000 = $60,000.00 gross profit for the year.
But you have to pay workers to pick them...if you try to pick them all yourself most will rot before they are sold.
And you have to have a place to store them until you take them to the wholesaler... and a truck to take them in
And you have to pay for the water and the fertilizer.
So if you hire two temporary workers for 4 months every year and you pay them 20 cents per Avocado...that is a $12,000 expense every year ($60,000.00 less $12,000 = $48,000)
And if you have a used truck that you make payments on...perhaps only $100 a month... but insurance, gas, and maintenance....$250 a month = $3,000.00 ($48,000.00 less $3,000.00 = $45,000)
Ok.....even if you already owned the land, you have to buy water. It can take up to 90 gallons of water to grow ONE AVOCADO in a dry climate. So we will guess that you get some rain there in So CAL so we will estimate it will only take 75 gallons of water per Avocado.
60,000 avocados will use up 4,500,000 gallons of water. Let us also say that you are paying the low rate of $3.00 per 1,000 gallons ...$13,500.00. ($45,000 less $13,500 = $31,500.00)
So the answer is close to $31,500.00 per year...IF you have no bug infestations, no fires, no mudslides and no sudden freezing weather. And no herds of wild anything tramping through your acre)