self-sustaining growing patches for sustainability

hello,
let's say i want to start a big self-sustaining farm. is it possible for crop to, lets say, harvest half of the crops and let the other crops be able to spread the seeds themselves?

thanks,
Bert

I think this is a useful pattern. The plants that produce lots of seeds are usually annuals or short lived perennials. The grow fast, and make seeds strategy is an adaptation to high disturbance in low stress environments (animals, floods, beaches)... or perhaps to extremely high stress environments where seeds are waiting for a chance rain (desert). Usually humans create their disturbance for them. Another approach is to use animals like chickens or pigs to create the disturbance. Timing is important. The other wild plants that will compete with your crop plants are important to know. Timing may be very important. You may be able to make more mistakes if you have lots of species in your self-seeding crop mix. It is an art form that we are very slowly rediscovering. I suspect if you don't orchestrate a disturbance for too long or your disturbance is too weak, than perennial or rhizomatous species that can withstand your disturbances get the upper hand.

so you suggest bringing chickens and/ or pigs in after growing seson and have them spread seeds? but won't they eat the seeds in the proces?

Quite honestly... I don't know the answer, and I have not seen an robust answer with my own two eyes.

Masanobu fukuoka relied of seeds in clay pellets in his system to reduce bird predation. He did that work but little else. It might depend on the species of plant, and how long you run the animals. Perhaps you might do some kind of animal treatment after 2-3 years, when perennial weeds become stronger? I have gotten a couple of years of kale to regrow, and my garden beds sprout from the seed bank, but eventually the grasses get strong, for me particularly Agrostis stolonifera.

I can't imagine that the chickens would destroy ALL the seeds, and a wild seeding is often to dense for good leaf production, so some thinning of the seed bank might be useful. I have one patch where I am trying to load the seed bank with vegetable seeds, but I run chickens and dump in mulch in winter, and do some spot tillage for the tough weeds. I am hoping to feed myself in spring and summer, and then running the chickens in fall or winter while leaving a vegetable seed crop to mature above chicken height. It hasn't worked well yet. But I see enough success to know it is possible.

For small plots, another type of disturbance could be mulch. In a school plot I just looked under the standing waste of lupine, and found lots of lupine seedlings germinating early in that protected environment. I don't know if they would be doing so well if I had cleared the bed rather than leaving the debris.

Bert, your question is very simple, but the answer is very complex. Some crops will re - seed well, some are perennial and do not need to re - seed often, some will spread by rhizomes, or runners OT other non - seed methods. Some crops are dominating plants that will out compete weeds consistently and some are pretty delicate and will lose out to other plants. Especially in a polyculture environment, you may have some crops that will reseed and out compete others you wanted to keep going.
yes, some crops will naturalize, reseed and keep coming back year after year. Some are perennials and keep returning from the same stock without reseeding.
And so, we arrive at the classic Permaculture answer - it depends.