I spent over 30 years of my life working in agricultural biology. Mostly this was in biological control of insect pests and weeds. At the same time I followed my interests in the evolution, life history, taxonomy, ecology and behavior of arthropods and often these overlapped as a basic understanding of all of these is necessary to properly practice biological control. I worked for a time under the direction of the late W. H. Whitcomb, one of the most knowledgable researchers in biological control in the country, at the University of Florida. I had lengthy experience in several crops, especially soybeans and citrus. I later worked here in New Mexico under various people, adding rangelands, pecans, alfalfa, and cotton, to my range of crops and forage. I have thus been able to witness first hand the state of agriculture in our country, including Puerto Rico, as well as having some experience in Mexico and lightly touching projects in Egypt, Israel and Argentina. The following observations are based on this experience.
When I started work under Dr. Whitcomb, biological control was starting to reassert itself as a viable methodology. Chemical control had lost some of its luster (although even now we are still using way too much of modern pesticides in my opinion) because of "Silent Spring" and other revelations. DDT and other chlorinated hydrocarbons had been banned, or were soon to be so, and the organic farming ideas of Robert Rodale were starting to not sound so crazy after all. Reality being what it is, we could not, of course, wean ourselves completely from chemical control - in many cases it was mandated for bank loans and in others it was occasionally necessary - but there was enough of a trend that organic food labeling has become common even in most chain supermarkets. The problem of course was that the miracle chemicals developed and extensively used after World War II had several down sides - they produced resistance in pests, they indiscriminately killed wildlife and beneficial insects, they required specialized techniques to apply properly, and they were often prohibitively expensive. On the plus side they cut back on such insect-transmitted diseases as malaria and for a while house flies were predicted to become extinct (Murphy's Law and evolution soon put an end to that delusion!)
Let us get one thing straight - we are absolutely dependent on agriculture and I know of no practical way, unless society collapses and we are forced to forage to survive, that we can get to some mythical elysian time when we were hunter/gatherers in some sort of Eden. It was never an Eden even when we lived like that and we have been dependent on agriculture for at least 5 thousand years and are not likely to go back. However, we can and must reform our agricultural practices, or we will not survive in the long run. All the wishful thinking in the world will not produce the fresh water needed to irrigate crops or bring back rain to areas that depend on it for their agricultural production, once climate change alters the rainfall patterns. Droughts in some areas and catastrophic floods in others have already cut agricultural production.
Of course population drives the need for mass production, but often people who could produce their own food by integrated pest management or organic methods are caught up in the "Green Revolution" of hybrid crops, sometimes at high costs and requiring large inputs of synthetic fertilizers and pesticides. In essence they are trapped by ideas once considered groundbreaking, but which have long since become the property of huge corporations who mainly have to satisfy their stock holders, and the latter are seldom farmers. To be fair, the Green Revolution has put off the reckoning that the Ehrlichs predicted in their 1968 book "The Population Bomb" (Barry Commoner criticized the book as not tackling the problem of food distribution,) but there are limits to how far we can go with this approach. At present we are nowhere near sustainable development and while there have been encouraging signs in some areas, notably China and some European countries, we need to do a lot more to reach sustainability. It does not help that many of our politicians in this country have blocked action on these issues because of their campaign money needs or ideology, and in some cases have worked to weaken what action has been taken.
Still, I have very fond memories of harvesting fruit (raspberries and grapes) and nuts (pecans) and of shopping at farmer's markets and stands, as well as "pick your own" blueberries. I have also enjoyed my visits to farms when I have been able to do so and was involved with 4-H and FFA for about 30 years over all. Farmers are also often the victims of a system that feeds off of their industry (See: John Oliver on poultry farming https://www.youtube.com/...) Farming is not the problem so much as unsustainable agrobusiness is. Unless we humans can get our acts together collectively, we are in a real pickle and I honestly don't know how we will get out of it!
What would a sustainable agricultural system look like? I can only give my opinion on this, which is somewhat informed, but I have never owned a farm or ranch and perhaps some of this may be infeasible.
1. The ultimate goal is to develop a sustainable system, which would be helped by stabilization and eventual drop in world population. This means that women should have more control over their reproduction (easy access to birth control and if necessary safe abortion) and should also be involved in the financial operations of farms and other economic systems.
2. Fertilizer should be not used in excess. Excess nitrogen eventually finds its way into creeks and rivers and causes algal blooms, which eventually causes eutrophication when the algae die.
3. Pesticides should be used sparingly following the "Least necessary" policy. Pesticides should also be timed to avoid peak natural enemies populations and if possible selective or less toxic synthetic chemicals or biopesticides should be used.
4. Good farming practices should be followed - contour plowing, crop rotation, hedge rows, interplanting, leaving understory in tree crops, etc. Top soil especially needs to be conserved and in some cases built up, something that does not work well with straight plowing, bare fields and border to border planting. Soil is a living material, as well as a carbon sink, and is best not heavily treated with harsh biocides. These practices should be monitored, as methods will need to be varied to fit the specific area.
5. Water sources, especially watersheds, should be protected from pollution.
6. Smaller farmers should not be forced into slave-like subservience to corporations.
7. Farm loans should be regulated so that farmers do not get in above their heads.
8. Farms should be part of a widespread long-term ecological plan that integrates farms, towns or cities, and wild lands.
This is a tall order and I'm frankly skeptical that these would be followed when an investor can get in and make a quick buck, then leave or impose onerous conditions on the farmers to keep the money flowing as long as they can. It is also possible that a growing population precludes methods other than mass production on factory farms. If so, perhaps nothing can be changed. However, this is our one and only planet and we had better do something right or face the consequences. I don't think we have much time.
Among books of interest (and there are many) I would strongly recommend "Dirt: The Erosion of Civilization," by David R. Montgomery, 2007, University of California Press.