Why are the deltas are called extremely productive lands?

Question

Why are the deltas are called extremely productive lands?

Answer 1

yes they are good for farming, their very fertile.

Answer 2

They are AWESOME for farming! They basically provide free irrigation for farms, and all the nutrients of the river end up at the delta, so you also have lots of fertilizer for your crops. Fishing is great at deltas, because so many species thrive where salt and fresh water mix. The entire reason that ancient Egypt had power was because even though they were in the middle of the desert, they had the Nile river delta to provide abundant crop yields. River deltas also make great ports for shipping, because traders along the river meet with traders from the ocean, and there's a lot of trading, and a lot of commerce.

Answer 3

The deltas receive soil and nutrients washed downstream by the river. They accumulate in the deltas making extremely fertile ground for growing

Answer 4

True, about the irrigation from rivers, and the nutrients they deliver.  A combination of natural and anthropogenic sources over thousands of years contributed to the "black dirt" of the deltas.  

During early glacial sheet movement in North America, the topsoil in the northern lands was literally scraped off, and deposited in the south.  

When early American development reached its peak in the Northeast, still more nutrient-rich soil was lost during heavy deforestation and farm development.  Due to anthropogenic activities, the banks of Northern rivers began to erode, and farmers' freshly tilled topsoil washed in with them.  The waters carried this downstream--into the deltas.  (This helped to fuel heavy cotton and tobacco farming in the South, because these crops pull a lot of nutrients from the soil.)