Hey Wadza! On agronomic practises i once heard that potatoes has to be ridged every week after 4 weeks is it so? I mean increasing the soil on the ridges to cover the potato stems
Every 4 weeks might be too much , I would suggest when necessary depending on your mode of irrigation and even your weed control mechanism , reridging can also be used as a way of destroying weeds
Yes it increases organic matter to the soil structure , just make sure there is no longer microbiological activity ( worms and insects in the manure for they can affect the potatoes