Bayard Kelby, Billie Jo's dad, is your textbook 1930s farmer. We're talking tough, weathered, hardworking, and committed—times may be challenging, but no matter how bad the drought gets, he's not willing to give up on his wheat crops.
When Billie Jo asks Ma where her father's hope for rain comes from, she explains that being a farmer is so woven into the fabric of who Daddy is that it would be impossible for him not to hope. From the attention he gives to his trade, it's clear that he loves the land and feels privileged to care for it, even when the drought makes it hard to "believe in rain" (14.7).
So where do this love of nature and strong work ethic come from? It probably has something to do with him serving in France during World War I. He was only seventeen when he enlisted, and while he doesn't talk much about his service, he shares with Billie Jo his memories of the poppies that grew along the roadsides, no matter how badly the fighting "tore France up" (24.3). Even though we don't know all the details, the fact that this is one of his most vivid war memories reveals a lot about his love of natural beauty.
Still, Daddy's tenacity about farming isn't always a good thing. He's often prideful and quick to reject the advice of others, even when it comes from his wife, who has quite the green thumb. Also, he tends to behave rashly and impulsively when confronted with tough situations. At the end of Part One, Daddy runs out into a crazy dust storm as though he can stop it by himself; then, after Ma's death, he takes her money and goes out and gets drunk.
Most significantly though, he's in such a bad place after losing Ma and with the farm's ongoing decay that he refuses to go to the doctor when he starts showing symptoms of skin cancer. Not only does this demonstrate a pretty bad case of depression on Daddy's part, but it's what finally sinks the wedge between him and Billie Jo, prompting her to set out on her own for bit. If he isn't going to try to save himself, she isn't going to sit around and wait for him to die.
Fortunately, though, things eventually look up for Daddy. Like Billie Jo, he emerges from the dust of the accident a stronger man and a better father. Billie Jo's short-lived exodus from home helps them to get talking about things, he decides to put a stop to his stubborn ways; he even gets a girlfriend. He becomes proud of his daughter and their shared heritage, and when the story ends, we find him in a place where life is about more than just wheat. He recognizes what he has and chooses to claim it as his own.