Human population is much bigger than what the earth can support sustainably.
The current farm practices are incredibly wasteful. We eat so much grains. The grains do not grow in a void. They grow on a stalk. This stalk is thrown away. We are not utilizing this stalk as much as we should. This stalk can be used to grow animals, which provide more food. Another problem with grains is that the stalk can only be used when it is dried and literally dead. A better solution would be to use vegetables, where the leaves can be used for animals while the plant is still living. This will provide better nutrients to animals. And in turn will provide better nutrients to us.
We are taking out micro-nutrients from the soil at an incredibly faster rate.
Add to the fact that we do not send back the human waste into the same soil where the food came from. The result is micro-nutrient depletion. It would be better to eat local. And fix the human waste distribution system to convert it into fertilizers and send it back to the land where the food came from. We will need to avoid chemicals that can be harmful for cleaning the toilets, so that the human waste can be used without trouble for fertilizing the land.
We are growing food by using artificial fertilizers. This does not seem to be very sustainable. We do not know what nutrients the fertilizers are missing that might be critical. The plant researchers are not omniscient. The micro-nutrients may not be fixable by just adding the constituent minerals.
I suspect that in a not so distant future, much of the land will start becoming barren. It will not grow anything. This will be the age of enormous deserts.
What will humans do?
I believe there will be a food shortage of a magnitude never seen before. I hope we don't reach this stage in my life time. It will be a living hell. I believe most of the technology will be lost, except for some technical people living from land away from population.
I hope people will understand and start to implement better practices to delay this horrific possibility till we find a way to control population. I believe the population will start to reduce once most of the women population is educated.