Soil Science Shenanigans and a pair of plum trees

A million years ago, when I was but a child, my father moved us into his aunt's house. My great-aunt's house had a large yard which was completely paved over. I remember my father breaking the cement at one end of the yard to expose the dirt under and plant some tomatoes and peppers and  herbs and such. I don't remember my father doing anything else to that dirt but clearing the cement pieces off of it and planting the seeds. It bears noting that I was born in the desert and that plants there grew quite well at all times of the year and that all you had to do was sow seeds and add water and something would sprout for sure.
The point of this story is that my father just planted the stuff in the starved soil under the cement and he got plants to grow.
As I was setting up the cage and as I continue to prepare the ground around the cage for future expansions I began to worry about the soil conditions in my yard. As it is, I live in the ancient sand dunes of the Arkansas river so the soil in my yard is well, sand. Luckily for me, the two previous owners of the house kept the yard well watered and so the soil has a good amount of bio-matter mixed in. Still, unlike my father I do worry about he soil.
This time around however, I don't want to spend lots of money like I did the first time to get my garden going. To start with, I began to compost. I bought a composting barrel years ago that remained empty. I have stuff in there now and it's already looking good. I also bought a tumbler which I assembled but never used. That baby is getting loaded this weekend.
That is step one. Once the compost begins to roll in, I will concentrate in small patches in the yard where I plan to grow more flowers and veggies. Eventually I hope to have a sizable composting operation to cover the whole yard.

The Fruit Tree Situation
I have four fruit trees growing in my yard. All four are well established. This year, with the postcard spring we are having, all four are loaded with fruit. I have a nectarine tree, a peach tree, a Granny Smith apple tree, and a plum tree. The plum tree has never yielded a single plum. The flowers develop into what looks like plum fruit but inevitably, the fruit falls off the tree long before they mature. This year is no exception; the tree is loaded with fruit and I wait in anticipation to see if this year is the year I will see mature plums.
Just in case however, I talked my wife into letting me sink $50 U.S. to acquire two additional plum trees. They are two different types of plum and I was assured that they will pollinate each other. We shall see.

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