Adjusting the N fertilizer factor based on soil health as indicated by soil‐test biological activity

Abstract Agriculture faces a dilemma with nitrogen (N)—it is often the most necessary external input to optimize production, several generations of farmers became accustomed to its relatively inexpensive cost, and it contributes to widespread pollution due to numerous loss pathways to the environment. However, standard N fertilizer recommendations have not accounted well enough for a key source via mineralizable soil N. Soil‐test biological activity (STBA) is strongly associated with mineralizable soil N, both of which become surface‐enriched with conservation agricultural management using soil health principles. A series of field experiments assessed the contribution of mineralizable soil N to the N supply needed to optimize corn ( Zea mays L.) grain and fall‐stockpiled tall fescue [ Schedonorus arundinaceus (Schreb.) Dumort.] production. This essay synthesizes how STBA along with cost‐to‐value threshold can be used to modify the N fertilizer factor to optimize economic return and avoid environmental degradation.