4R nutrient stewardship—are we there yet?
4R nutrient stewardship is an innovative approach to best management practices (BMPs) for fertilizer. It ensures that the right source (or product) is applied at the right rate, in the right place, and at the right time (Roberts, 2007; Bruulsema et al., 2009). In the lead article of a 5-part series on 4R Nutrient Stewardship in the American Society of Agronomy’s Crops and Soils magazine, Bruulsema et al. (2009) wrote “This simple concept can help farmers and the public understand how the right management practices for fertilizer contribute to sustainability for agriculture. Getting practices “right” depends on important roles played by many partners including farmers, crop advisers, scientists, policymakers, consumers, and the general public.” The concept of 4R stewardship not only provides structural stability to our own management decisions, but also offers us a simple and effective means of communicating to those outside agriculture about how our management contributes to sustainability. To truly be “right” practices must be site-specific for the crop, field, and for the zone within the field. Yet, the scientific foundation upon which 4R nutrient stewardship is built and that leads us to nutrient BMPs is universal.