Like a lot of Iowa farmers, Humboldt farmer Doug Adams hustled this year to get another crop planted, a cover crop, just before his corn and soybeans were ready for harvest. And like many farmers, he brought in air power to get the job done.

With the harvest workload coming on, finding the time to apply a cover crop before the cash crop is harvested is a challenge. Aerial applications of cover crops are keeping Iowa pilots like Ralph Storm of Webster City very...