In-season management of nitrogen is a critical component in the drive to increase the nitrogen use efficiency of commercial crop production. Increasing nitrogen use efficiency itself has become a prominent issue due to both economic and environmental/regulatory drivers over the last decade.   Solum, Inc (Mountain View, CA) has developed a new sensing technology to enable the immediate and direct measurement of soil nitrate. This allows rapid and economical soil measurements, which in turn opens up new opportunities for improving nitrogen management through in-season management.   We will discuss the fundamental science behind Solum’s technology and discuss applications of the system for in-season management.