>>3481602 adult humans require 0.4 acres of arable land to survive on. Average 4 hours of work each day, per person for maintenance. Include the amount of work needed to divert or store water: another 1-8 hours depending on ease of access to water. Add 10-16 hours per day during harvesting, processing, preserving, and storing. Add another 0.1 acre for every teenager or 2 children; with that aid remove 4 or 2 hours per day from the adult workload. What do you end up with? A clusterfuck. Mind you that is ONLY basic survival.
Now let's go up a notch: 4 adult humans will require 0.9 acre of arable land, with 2-3 hours of work each day between them, and 2-3 hours of water maintenance for 2 persons. You can see how quickly scaling a farm community upwards becomes. Let's say there's 3 teenagers and 6 children: this leaves the adults 5-6 hours more time per day to work on other projects and tasks.
That is, until you reach the 3 Problems:
#1: "space is at a premium, we have X people with Y accommodations, and there isn't enough time/knowledge/skill/tools to build more". This is the most common one, due to either shortsightedness, lack of education and real world experience, pressure, or being in a shitty area. How to resolve this? There's a famous quote that I enjoy stating often: "Any idiot or moron can build a bridge that lasts a thousand years given all the materials and time he needs. On the other hand, it takes a true genius to design a bridge that will only last twenty years." In short: overbuild. everything. No shitty little 1-room house made of single-stacked logs, make that fucker a fortress of triple-layered logs and externally protection by a mountain of form-fit stones.
#2: "we don't have enough water!" Can't change weather patterns unless you know how cloud seeding methods. Not enough water? Reduce number of crops. Too much water? Add a small amount of sand to the soil for additional drainage. Flooding constantly? You picked the wrong location.
#3: "we can't expand more because we don't have more arable land". The third most common and least understood. You cannot simply expect to plant a seed and water it. Certain crops will take a few years to adapt to even marginal changes from their native spread, so long as you let them wild seed and spread on their own without 'aid'. Others will not grow anywhere save for a tiny region. Be selective, study the potentials, be aware of problems such as parasites, bacterium, fungi, and what will, or may, prey on select crops. Also:
ROTATE YOUR FUCKING CROPS. """Modern""" monoculture methods have fucked over the vast majority of commercially farmed land, so don't even try.
#4: arguably both the least and most major problem to consider is whether or not you will be planting genetically engineered crops. Main liability with those is that the vast majority have been engineered to REQUIRE doses of glyphosate in order to sprout. If you've been 'spraying' for years or you decide to take over a place, guess what: that soil is heavily contaminated. Takes over 5 years for that shit, among other herbicides, to BEGIN breaking down. You will not realize this immediately, though common signs are a lack of certain flora not growing in the vicinity.
As for fruit trees... do NOT depend on them for 'efficiency' unless you've selected a hardy Old World variety. Most are water hogs. If they don't get enough you will have wasted time, space, and water over several years that could have been used for another crop. A firmly established fruit tree can provide a
reasonable amount of fresh and preserved food for at most 4-5 people, all depending on species, height, and difficulty acquiring. Don't plant exotic fruit trees unless you have studied their needs.
Nut trees and fruit-bearing vines have the same problems as above, except they are targeted more by birds and insects. Walnuts are infamous for this, as are almonds, watermelons, cantaloupe, etc. etc. etc.