Why do my pumpkin seeds unplant themselves?

I am planting them above ground, on farmland, with nothing directly overhead to block the sunlight. I had 12 pumpkin seeds, and none of them stayed. Occasionally, they would pop out instead of simply disappearing, so I tried replanting them, this time with torches on fence posts next to them in addition to the abundant sunlight, to the same result every time. A couple of wheat seeds popped out too, but are now growing seemingly fine. I am completely out of pumpkin seeds now, though. I have the 0.16.05 version of PE on the Kindle Fire.

Solution 1:

If your fields aren't irrigated, plants might uproot. Try to put some water patches nearby or an irrigation ditch, using a bucket.