Susan L. Sakmar, an energy analyst in San Francisco, cautioned that the fracking boom could slow and that guar alternatives could be developed. But Mr. Economides, the Houston fracking expert, dismissed such talk. “There are no easy or cheap alternatives to guar,” he said.

That is good news for guar producers. Farmers, traders and processors around Jodhpur admitted fulfilling some long-held dreams with the profits they made last year. Some took trips to Europe; some bought gold; others got married.

At a Massey Ferguson tractor dealership in Jodhpur, where sales have doubled in recent years, Nathu Parjapat of Haripura was buying a tractor for his father-in-law, whose own profits from farming guar allowed him to provide a dowry of 12 grams of gold and half a kilogram of silver when Mr. Parjapat married his daughter.

“So now I’m buying a tractor for him,” Mr. Parjapat said as his father-in-law stood next to him, nodding with grave approval.

Mr. Singh, the farmer with the new house, said he would plant his entire field with guar this year instead of spreading his risk among other crops. His family is able to sleep on the stone roof, where a constant breeze keeps them cool. His old mud house, now occupied by goats, has a roof made of sticks that did not allow such a luxury.

Mr. Singh’s sister, Issa Rathore, showed off a silver ankle bracelet and a toe ring, both bought with guar profits. But her smile quickly vanished when she was asked whether she expected a similar windfall in the coming months. She glanced at the sky, and the children around her grew hushed. “Will the monsoon be enough this year?” she asked. “Who knows?”