Historically, at least since the mechanization of agriculture began in earnest, there have been two primary measures of agricultural productivity, the amount that could be grown on a given acreage and the percentage of the population required to feed all of us. The former, measured in bushels or tons per acre, has generally been increasing and the latter, measured in man-hours per bushel or ton, decreasing for at least the last hundred years, albeit more so for some crops than for others. (A consequence of the decreasing need for labor to produce many staples has been the migration of the children of farmers to cities, where they helped keep the cost of labor low in other enterprises.)
Corn (maize) is a good example of a crop for which these conventional measures of productivity tell a story of brilliant progress, with the result that corn is cheap enough to use not only as livestock feed, to be converted into meat and dairy products, but as the feedstock for production of ethanol for fuel, competing with fuels refined from petroleum pumped from the ground, rather remarkable considering that corn kernels represent only a small fraction of the biomass of a corn plant and that fermentation and distillation aren't particularly efficient processes.
Crops that fair less well by these measures include many vegetables and most fruits, which have been becoming gradually more expensive, especially as compared with grains that are easily handled mechanically, but even compared with meat and dairy products from grain-fed livestock. One major consequence of this has been that people generally consume more grains, meat, and dairy products, and less fruit and vegetables than they once did, before the mechanization juggernaut got started and while vegetable gardens were still common.
So, by an altogether different measure, how healthy the average diet is, mechanization has been a disaster, so far. I say "so far" because the essential problem is that, so far, mechanization has favored crops consisting of hard, dry seeds, that are easily handled in bulk, making other crops needed for a balanced diet relatively less affordable. In happier economic times this would matter less, as people would simply pay the premium for a healthier diet, but the times being what they are people are scrimping however they can, including with the food they consume.
There are other ways of measuring productivity: energy use*, soil gain or loss*, water use and contamination*, and the degree to which a given practice denies space to native flora and habitat to native fauna. By any of these measures, conventional mechanization comes out looking at least shortsighted if not dimwitted.
*(per unit produced)
So is the answer to turn back the clock on agricultural technology, to replace the plow with the hoe and the drill with the planting stick? I'm not prepared to make that argument - although I've no doubt others would - aside from noting that gardens are a better use of many urban spaces than are lawns, and there is no further need for rural communities to supply cities with cheap labor, since those cities are already well supplied, and many rural areas suffer from depopulation.
Instead, my position is that we need to take mechanization to the next level, replacing dumb machines suited only to bulk operations with smart machines capable of performing well-informed, detailed manipulations, for example controlling weeds by selectively pulling them from the ground or pest caterpillars by picking them from plants (unless they've already been parasitized, as by wasps) rather than by applying poisons.
Given machinery with an adequate array of sensors and a sufficiently broad range of optional actions, applying best practices becomes a matter of mating these with processing power connected to an expert system, and of programming.
It gets better, because the same system that works the land can be used to improve the expert system through experimentation and, in routine operation, by accumulation of data to which statistical methods can be applied, and can also be used to improve the crops themselves, as for instance by leaving the best formed, most insect resistant cabbages to go to seed.
The bottom line is that this approach can make available the mechanical equivalent of an attentive expert gardener, at a cost, given predictable economies of scale, that would make possible the wholesale replacement of conventional, traction-based machinery and methods with more adaptable machinery bringing a whole new repertoire of methods to bear, one far better suited to the production of the fruits and vegetables that have been becoming unaffordable under the current regime.
As for the other measures of productivity mentioned above, such machinery, since it wouldn't need to turn soil in bulk and could operate long hours without continuous supervision, would consume energy at a relatively low rate, suitable for supply from solar panels or via the grid from renewable sources. It could operate through continuous ground cover, all but eliminating soil loss, and with minimal use or complete non-use of herbicides and pesticides, reducing soil and water contamination. Ground cover, mulch, and the humus accumulating from decaying roots can also reduce the need for irrigation, and the ability to create local varieties through seed selection based on the health of maturing plants can further reduce it, as well as helping to adapt more quickly to climate change. Making room for native species, something that can only be accomplished in conventional practice by leaving land completely undisturbed, becomes a matter of programming the system to leave certain species alone, wherever it finds them, even to the extent of tolerating some crop loss to native fauna, and to leave anything it can't identify alone until it can be identified.
Such machinery might not be able to compete with conventional practice in the production of corn and other bulk commodities, at least to start with, but it also wouldn't consume prodigious amounts of petroleum-based fuels. Moreover, development and rapid deployment of such machinery would drive the growth of a new, potentially domestic industry, one that would also work to the benefit of materials recycling efforts, more efficient transportation, and on and on.
The R-word I haven't yet mentioned is robotics. While such machines probably aren't what most people first think of when robots are mentioned, their creation and production falls squarely within the discipline of robotics, composed as they would necessarily be from robotic technologies.