It's a labor intensive process growing vegetables here in Algohongo and Xunil.
There weren't any mechanical devices to be seen, outside of pickup trucks, water hoses, and an occasional set of irrigation sprinklers. We spotted one small water pump, but largely watering was done with wooden water "scoops," using water from the ditches surrounding each field.
The soil looked rich and deep; here was one spot where additional mulch/compost was apparently being added. Recently harvested fields (where dusting of lime was apparent) had me wondering about the pH of this presumably volcanic, but VERY hard working soil.
The mild spring-like climate, even here in the Western Highlands, allows growing of crops continuously, at the what we can "cool season" vegetables in the SE U.S.
Hoop houses seemed to provide enough additional warmth for tomatoes and maybe peppers, although I think most were coming in to the markets from more lowland areas.
But my take home was just how labor intensive in these commercial market gardens. I'm familiar with the process as a vegetable gardener myself, and know what hard work it is; the vegetables looked beautiful, and were carefully cultivated. My guess is that they were reasonably prosperous compared to the dry land farmers; I hope they're finding good markets for their vegetables. The guidebooks say these are prosperous towns, and they certainly look the part, compared to many others.