We should stop focusing on the plants and focus more on the soil. Better soil = better water retention = less work with irrigation = healthy plants = healthy planet.
> The belief that only small-scale, non-mechanised agriculture without the use of chemicals respects biodiversity, and that tradition is key to the future, is illusory. In reality, small-scale unfertilised farming of annual crops or unregulated grazing in the tropics are major causes of destruction of soils and forests.
The only problem here is the "annual crops or unregulated grazing" because on a diverse agroforestry the trend is the opposite, the soil gets better and better as years goes on. More organic matter falling on the soil = better soil, as long as you don't remove the organic matter you're good to go! The main problem lives here, a lot of people clean the grass and burn it, the soil should never be uncovered, you can cut the grass no problem but leave it there to compost and improve your soil, just like happens in a forest.
> Chemical use is still, for the most part, equated with environmental destruction. This is a false image, one that leads people to turn away from science and technology. We cannot go back to the ill-designed agricultural systems of past centuries with their famines and harvest failures.
Sure, this so called "science and technology" is what made the land "often polluted, and unsuitable for horticulture" in the first place.
Grow food forests, build forest soil! The forest never needs any chemical added by humans, it doesn't have pest problems, why? It's diverse. Diversification guarantees your surviving, when you have only one source of food (or money, or anything) and it dries out you starve, but if you have multiple sources you can not only survive but have more colorful plate too.
Sure it's more laboring to do forest, but we can change our machines to work with forests instead of mono-cultures, that's the way to go, the more mature a forest gets the less human intervention it needs. Here in Brasil I'm seeing a few people starting to develop machines to work with agroforestry, that's the future of food IMHO: forests!
Well, maybe I'm biased, since I found out permaculture and agroforestry I'm in love, couldn't be happier :)