Corn must have adequate amounts of nitrogen (N) and phosphorus (P) for profitable production. Nitrogen and phosphorus are also the nutrients that produce excessive algae growth in surface waters when concentrations increase above certain critical levels. Profitable and environmentally sensitive corn production requires that N and P be managed in an efficient manner. Economic returns from the use of these nutrients can be maximized, while the potential for surface and groundwater enrichment with N and P can be minimized with the use of appropriate technology. Available technology includes soil testing to evaluate residual soil nutrient supplies, and the use of proper application rates, methods, and timings.