Tomorrow’s grain rows, vegetable fields, and specialty crop groves will be much busier places than the relatively passive acreage of yesterday. On the surface, sensors built into crops will signal soil conditions; digital irrigation systems will precisely direct water streams; and robotic guardians will pull weeds. In the air above, satellites and drones will photograph plants with enough precision to count the spots on a ladybug’s wing. In the soil below, new wonders of botanical manipulation a…