Environmental impactPrecision agriculture is an information-intensive management strategy where production inputs such as fertilizers are matched with site-specific needs of crops. Conventional soil sample collection and laboratory analysis for nutrient levels is costly and time consuming when applied spatially as is required in precision agriculture. Sensing soil macronutrient (nitrogen, potassium, and phosphorus) status in real time as a machine moves across a field would be more efficient. Sensing systems linked to variable-rate fertilizer application systems could target fertilizer to sub-field areas where it would be beneficial, reducing fertilizer application where nutrient levels are already sufficient. Such an approach could lower food production costs and reduce potential for negative environmental impacts to water supplies due to over-application of fertilizer nutrients.