This past season I decided to experiment with mulching some of my oca and yacon beds to see what the differences would be.
I mulched two beds of each, left two beds unmulched as I usually grow them, and grew two beds in the open with no mulch or shadecloth. Note that in my Australian scorching summers I have to use 50% shadecloth row covers on most of my vegetables.
Yacon: There was almost no difference in production of the mulched and unmulched beds. The only difference was a very slight reduction in the amount of edible tubers in the mulched beds but it was not very significant. I did find that the plants in the mulched beds started to shoot weeks after the unmulched beds, I even overplanted one bed with melons as I thought they had rotted. The melons grew quite happily among the yacon. Basically there is no advantage in mulching yacon.
Oca: The oca in the mulched beds also started growing weeks after the unmulched beds, because of the stable temperature I imagine. There was a huge difference in the health and productivity though with the mulched beds having much healthier plants and almost no sign of stem rot which is a problem with oca here caused by heat. There was a marked rise in the ratio of eating size tubers (over 5cm) to small tubers in the mulched beds. I will certainly be mulching from now on.
I haven’t mulched oca up till now and thought that I would lose a lot of tubers due to mice and slugs but although I saw many slugs there was little slug damage, and I saw no mice in the straw. I think there would normally be more mouse damage but this year there wasn’t many to be seen.
All the plants in the uncovered rows did very badly with nearly all the oca dying and the yacon growing very small and producing very few eating size tubers.