What pushed great plains farmers to leave their lands and migrate to california?
the desire to pioneer new farming methods in the west.
belief in another discovery of gold.
difficult conditions brought on by a severe drought.
improved subsidies offered to california farmers.

Difficult conditions brought on by a severe drought pushed Great Plains farmers to leave their lands and migrate to California.

Explanation:

The farmers from Great Plains also called the refugee farmers or Oakies, who migrated to California from Southern Plains. They had only two reasons to migrate, one is The Great Depression and the other one is the Dust Bowl.

The Dust Bowl is nothing dust storms that resulted in drought and declined dryland farming during the 1930s. This majorly affected the agriculture and ecology of the Canadian and American grasslands and plains.

This severe drought resulted in difficult conditions. That pushed the Oakies to move to California.

you can't, there's no way sorry

because they can and they wanted to.