Answer: the dam cause no more fertile soil to enter in to farmers land for growing crops hope this helps :)
Explanation: this dam has caused a big change to the lifes of farmers downstream from the dam. Usually when the river flooded once a year before the dam was built. It deposited fertile soil from upstream on its banks downstream. This washed up soil was extremely furtile, and renewed itself every year at in flood season. But now, since the dam was built the annual flood has been stopped. Causing all the farmers downstream to have to use fertilizers to grow their crops, which makes it more expensive.