[evunveot]

It would be maximally eco-friendly to transition agriculture away from chemical fertilizers (and pesticides, herbicides and fungicides/off-farm inputs in general) by focusing on soil generation and ecosystem development primarily through radical plant diversity/polyculture. For example,

https://www.youtube.com/watch?v=K8_i1EzR5U8 Cover crops, no-till & soil health - Quorum sensing in the soil microbiome (understanding the role of soil microbial interactions for soil health); Dr. Christine Jones

Early manifestations of this movement are in traditional farmers eliminating tillage/plowing ("no-till"); converting fields to rotations with diverse cover crops (not just a legume monoculture like soybeans, as has been practiced for thousands of years) to reduce or eliminate the need for fertilizers; reducing fallow periods through practices like "planting green" (sowing cash crops while the cover crop is still living), interplanting and companion planting; and use of fungal and bacterial biostimulants (application of cultivated strains of specific microbes and/or large scale brewing and application of compost tea). I view these practices as on the same spectrum as less commercially oriented approaches like permaculture food forests and foresee some kind of merger in the future.

Unfortunately, industrial influence will continue to steer research and advocacy toward hub-and-spoke systems (centralized fertilizer/GMO seed production + farmers selling into centrally managed distribution channels, or ultimately just the "growing" of calories in corporate-owned lab-factories) and away from distributed alternatives (farmers growing food using local inputs and nitrogen from the air via microbial activity + selling to local markets), simply because hubs allow for concentration of profit and control.

[ch4s3]

How do these approaches propose producing enough bulk calories in the form of wheat, corn, and rice to support 8 billion people? Also, how to the aim to overcome the labor issues in more developed economies? The labor inputs for these methods always seem to be FAR higher than conventional agriculture.

[evunveot]

I've encountered less about rice, but the transitional practices I described can be used in the (otherwise conventional) growing of corn and wheat and can produce comparable yields for lower cost to the farmer, directly in the case of reduced fertilizer cost, but especially when you factor in reduced losses to drought events from the ability for high organic matter soil to absorb and retain water, as well as greater resilience to disease and pest wipeouts due to healthier plants and a more diverse farm ecosystem. It's all somewhat anecdotal, though, since this sort of thing resists formal research, both from the funding angle (doesn't lead to profitable results for industry; not sexy/high-tech enough for ambitious academics and their departments) and the experimental design angle (too many variables; farmers are all trying out different things in different ways and different climates).

From the permaculture/food forest/holistic side, you can certainly vastly beat the economic output of conventional agriculture (e.g. just growing corn) on a $/acre basis when you integrate all the possible enterprises available (meat, eggs, vegetables, herbs, fruit, wood products, flowers, ecotourism, etc.). I'm not sure in terms of marketable calories per acre, i.e. stuff human beings actually want to eat, but I'd think at least within an order of magnitude of corn (eggs go a long way). But you're right, the bottleneck is availability of farmers, since one farmer with machinery can grow hundreds of acres of corn or wheat at millions of calories per acre. I think it's fair to say there's plenty of opportunity for people to become farmers if they want to, though, in that information is more accessible than ever and there's land available.

We do have the example of Gabe Brown [0], who I believe manages 1000+ acres regeneratively with only his family for labor. I don't recall any attempts to calculate his kcal/acre, though. Farmers are understandably more concerned with $/acre.

[0] https://www.youtube.com/watch?v=ExXwGkJ1oGI