Spain hoped to spread Catholicism in its American colonies. Spain was a very Catholic country at the time and remained very religious for centuries later. One of the main goals of colonization other than taking over and extracting the riches from the countries was to Christianize the population and convert them. This actually proved largely successful as an overwhelming majority of countries who were colonized by the Spanish identify as Catholic or a Christian denomination.
The floods happened yearly and the slit was loose soil carried by water that creates rich farmland. ... As the flood waters receded the silt was deposited along the river banks thus providing fertile soil for farming.
