Understanding global and historical nutrient use efficiencies for closing maize yield gaps
Global food security must address the dual challenges of closing yield gaps (i.e., actual vs. potential yield) while improving environmental sustainability. Nutrient balance is essential for achieving global food security. Historical (in distinct “Eras” from late 1800s to 2012) and geographical (in United States vs. remainder of World) changes in maize (Zea mays L.) grain yields and plant nutrient content (N, P, and K) were characterized from studies (>150) with known plant densities. At the community scale, greater yield to nutrient content ratios (physiological efficiency, PE) were documented for United States vs. World. The U.S. historical trend displayed increasing gains for community-scale yield and nutrient uptake, except for a recent decline attributed to weather. At the individual-plant scale, geographic PE differences over time were primarily explained by changes in yield, and secondarily by nutrient content changes. Despite wide variation, high-yield maize in both geographies was associated with balanced N/P (5:1) and N/K (1:1) ratios. More scope exists for maize nutrient PE gains in developing regions. Achieving balanced nutrition in optimally integrated soil-crop management cropping systems will facilitate simultaneous realization of high-yield and bio-fortification goals in maize improvement efforts.