Dunno Aaron! If you look at the projected increase to about 9 billions on this planet by 2040 or 2050 the rising living standards and adequate food production hinge almost totally on the availability of cheap energy.
Cheap energy as the history of the development of our industrial society has proven was the reason behind the increased availability of food as food production could then move from a peasant type production to a mechanised system and from where as I have mentioned above up to 80% of the income of the lower classes was spent on enough food to enable them to live to where food now takes less than about an average 20% of a worker's wages.
The advent of cheap energy meant iron and then steel could be manufactured in large enough quantities and so cheaply that it could be used to build the machines that provided work and better pay and etc
The ability to travel to employment with the advent of trains plus water supplies, sewerage and consequent better health, food transport so that seasonal shortages or surpluses in a region could be supplied from other areas meant that the rapid rise in living standards during the industrial revolution and so on all rested on cheap energy.
Cheap energy meant the production of artificial fertilizers at prices where they could and can be used to dramatically boost food production.
With cheap energy and therefore cheap fertilizers and cheap transport opened up many other areas for food production in the late 1800's and the early 1900's
In fact South Australia was the world's largest wheat exporter in the late 1800's and that was entirely due to the unique SA situation where their main grain growing areas were within 50 or a maximum of about a 100 kms from the coast.
There is nowhere else in the world where this situation existed, where big acreage's of wheat and grain was grown so close to coastal ports.
With that situation the horse drawn wagons which was the only heavy transport in those days could haul wheat to the all those little ports that line the SA gulfs where the bagged wheat was loaded onto the sailing ships for transshipment to overseas markets or to other Australian markets.
Rail and the advent of road trucks, all tied to the availability of cheap energy, of course eventually finished this trade as other regions world wide could then compete with SA wheat.
Just to back track on fertilizers.
Fertilizers both the phosphorus based fertilizers and the nitrogen fertilizers take a lot of energy to produce.
When these fertilizers reached over a thousand dollars per tonne due to the Chinese demand a few years ago, a lot of farmers did not use any fertilizer or just cut right back.
OK for a year or two as the crop can draw on unused reserves of fertilizer in the soil if you have been conscientious about your farming.
Now with the crazy demands of the global warmers and politicians to put a huge tax on all sources of energy then fertilizers and chemicals and numerous other necessary inputs to food production will be reduced unless there is a dramatic rise in prices received for grain which of course leads to dramatic rises in food prices of every type.
A lot of grain is used in animal feed, the starch from grain such as wheat, is used in food of all sorts and in some industrial production.
Transport costs rise and ditto above as grain is shipped everywhere around the world and in fact the grain supply pipeline is estimated as 28 days.
If the world's grain supplies fall below 28 days supply or even down near that number then the world no longer has enough food to feed itself, a situation I have sen at least twice in my lifetime.
Huge taxes on energy as wanted by the warmers and politicians will create immense problems and probably lead to some potentially serious food shortages as areas go out of food production as they cannot afford the long distance cartage costs for the inputs or their produce and / or can no longer afford the much higher priced fertilizers and chemicals that use a lot of energy in their production.
Unless there is a dramatic rise in the price of food to compensate for the big increases in energy costs due to the global warming taxes and imposts.
When it comes to whether there is and can be on farm sustainability of production, the answer to your question as it applies to Australia, the USA, Canada, Europe and other similar advanced countries is Yes!
I posted about the 1940's and how the farmers of the 1950's completely rebuilt their soil fertility within about a decade using nitrogen fixing plants that were plowed back into the soil to provide the essential nitrogen for the following crops and to give dramatic increases in the soil organic carbon content and matter.
A measure of soil fertility is Organic Carbon content or levels.
Australia's soils have a very low organic carbon content like only one percent or a bit better and as I have posted they are some of the poorest soils on earth as Australia being the oldest continent has highly eroded soils that over the aeons have had all their nutrients leached out.
American and European soils being much younger on average have high organic carbon levels of up to 5 and 6 per cent which is close to peat type soils.
Cultivation breaks down the organic carbon and converts it into nitrogen without which the plant will not grow as the processes within any plant need nitrogen and CO2 to function and in fact it is calculated by the plant researchers that the rise in atmospheric CO2 levels of perhaps some 40 ppm over the last 30 or 40 years has actually accounted for about 20% of the increases in yields that have occurred over this period.
Note, 20% OF the increases in overall yield, not a 20% yield increase. CO2 Science
gives a set of tables where crops give their highest yields at certain CO2 levels and for wheat the highest yields come at about 700 ppm of CO2.
Atmospheric CO2 levels are calculated to be about 390 ppm at present but considerable variations in levels around the globe are now known to exist.
As above cultivation breaks down soil organic carbon content and therefore continuous cultivation as it was practiced prior to the advent of the modern chemical herbicides led to ever lower fertility levels over the long term.
Since the advent of the use of more and more weed controlling chemicals,ie; herbicides, farming technology had changed dramatically as we no longer have to cultivate perhaps 8 or 10 times to control weeds before planting a crop.
Now we use a couple of sprays to kill the weeds and in a lot of cases NO cultivation at all before planting so far more soil organic matter other than what the crop needs is retained.
Also with herbicides we can control weeds and kill any previous crop regrowth that springs up after the first seasonal winter rains and then plant a new crop of a different type to reduce disease problems straight into the old crop stubble or the residue and stubble of the previous crop.
So instead of getting one crop every two years as in the 1970's we are now getting a crop every year off the same area [ if it ever rains! ]
That is one of the ways we have just managed stayed in business as the consumers force the prices ever lower.
The really interesting thing here and there is a lot of research and innovation in machinery and technology going on to enable us to do all of the above is that when we retain the old crop residues, the stubbles, the soil organic carbon levels remain relatively constant and in a lot of cases show a very slow increase in levels, something that was not realised could be done some 30 or 40 years ago.
In other words, the soil when chemical weed control is used, when stubbles are retained and when the right artificial fertilizes are used actually very slowly increase in their fertility.
This doesn't happen everywhere as soil types also have big bearing on the results but that increase in fertility or the maintenance of fertility using modern technology and techniques, despite increasing tonnages of grain being taken off an area, is far more common nowadays than a significant loss of fertility due to the cropping of the land.
And this is a world wide trend in cropping and grain growing
The next factor is by using chemicals to control weeds we are not pounding the soil down all over so a lot less traffic across the paddocks means that the soil is far more permeable which allows a lot more rainfall to penetrate into the ground instead of sitting around and either running off or evaporating away,
This of course mean more deep soil available water for the growing plant.
Retaining the previous crop's residues also protects the soil surface and increases soil water uptake as well although special machinery has had to be developed to sow through the stubbles of previous crops as normal machinery just blocks up with the stubbles or crop residues.
Some farmers, and most of us use the automatic GPS steering systems nowadays in our tractors, sprayers and harvesters, only use one set of regularly spaced wheel tracks across their crop paddocks right through the crop growing season and all machinery follows these sets of wheel tracks for the entire season and in some cases they are the only wheel tracks that are used full time every year that paddock is under crop.
Again this is to keep the soil as open and permeable as possible to allow rain water to permeate into the soil and to give a nice soft open soil for the plants to grow in.
Yes we can retain fertility and we can continue to increase yields of most of mankind's most important crops but there are now signs that we are closing in on the biological limits for many crop yields and as we do so, as with all systems operating near their limits, smaller and smaller problems have larger and larger repercussions and that in crops means reduced yields.
The UN's Food and Agriculture divisions [ FAO ] has calculated that the world neds another 200 million hectares of crop land to feed the 9 billion people that will be on this planet by 2050 [ global population is calculated by demographers to start to decline after 2050 ] however the FAO can only identify some 94 million hectares that could still be converted to crop land but most of that 94 million Ha's is under forest and that is going to really cause a ruckus in the green camp.
So mankind's choice may yet be, do we feed the extra mouths or do we let them starve to save the environment.
I wont be around to see that but you might be right in the middle of it and then the world will see just who has the real morality and who really cares about people or does the environment come first?
Yep farmers are real dumb and they rape the soil and despoil nature and they feed each and every one of the 6 3/4 billions of human beings on this planet.
And they will continue to do so for the many, many more generations of the human race still to come.
And remember; Don't criticise farmers with your mouth full!
Hope the above epistle above answers some questions, Aaron.
Regret not the past.
Fear not the future