"Soylent Green is people!"
The problem with the type of soil we have in the farm is that its mostly clay. It may be good for something else, but it's quite a challenge for gardening.
Since we have all these plants that require good soil to grow healthy, they have been importing this precious commodity from another garden. Good thing is, it's free. The only catch is that they have to travel several kilometers and haul it back to the farm themselves.
After a few weeks the mound of imported good earth was getting used up. Then mom realized that there is a great source of fertile soil right within the farm. Remember the two drained fishponds? Well up to now they're still dry.
With all the fish poops plus other animal poops, uneaten fish foods, dead leaves and other biodegradable gunks all mixed up and accumulating at the bottom of the pond, the soil eventually got enriched by these free nutrients. After years of not seeing daylight the mixture of wastes have decomposed and aged into a rich plant medium. Today, this is where they're getting the soil needed by the ever growing number of plants.
By using the soil in the pond, they don't have to use synthetic fertilizer. Soylent Green is people, but our pond soil is 'green'.
"Soylent Green" is a science fiction movie made in the early 70's and set in the year 2022 when the world is burdened by over population and available resources are almost used up. To feed the people, food is rationed and one food being rationed is "Soylent Green" wafers.
If you haven't seen the movie, watch it and find out what Soylent Green is made of.