planting too few crops, which allows the topsoil to erode away
They wanted farmland they could sell and make a profit.
the rain fall
The farmland was wide and grassy.
Farmland produces and sells beef
There are several possible words:For useless meaning valueless, the opposite could be "treasured."For useless meaning not workable, the opposite could be "effective."For useless meaning not required, the opposite could be "necessary."For useless meaning worthless, the opposite could be "practical."For useless meaning inappropriate, the opposite could be "pertinent."For useless meaning unhelpful, the opposite could be "desirable."useful - look it up in a dicitonary and you'll see a picture of me.
By Hand
Millions of acres of farmland became useless, lots and lots of people lost their homes
Their farmland was rich, and they can produce lot more than they could eat, so they traded with other countries.
If you are an artist you will know. And if you make something you will have proved that those things were not useless.
Probably stealing the farmers crops and food.
Grassland
to make a farmland