These Yam heaps were manually made As in a human was heapibg this up using cutlass and hoe You can see the cutlass in print on top of the heaps Do you imagine how many hours it rake to heap this up using hoe. Now imagine if this were to be done by tractor couple implements * it will save time * it will prevent the human body stress How often do you think a man can continously create this type of heap without breaking down? This is one of the reason food are becoming expensive This is why we will