A Brazilian scientist whose work shows farmers how to shift crop production toward more biologically based solutions instead of chemical fertilizers is being honored with this year’s World Food Prize. The organization announced Tuesday that Mariangela Hungria has won its $500,000 prize. Hungria is a microbiologist. For 40 years she has been researching biological seed and soil treatments and working with Brazilian farmers to implement her solutions. Since early in her career, she has focused on a process called biological nitrogen fixation, in which soil bacteria can be used to promote plant growth.