Effects of Agricultural Intensification On Corn Yield, Root Biomass, and Nutrient Use.

This study demonstrates how a greater understanding of interactions between agricultural inputs and management practices can be used to positively influence corn yields in an efficient and sustainable manner.  The experiment was conducted in 2011 and 2012 in east-central Illinois.   Five “Technology” treatments (plant population, nitrogen (N) fertility, non-N fertility, hybrid trait, and fungicide) were applied at two levels (traditional and advanced) to test for effects of each Technology factor alone and in combination.  Additionally, crop rotation and residue management treatments were applied at two levels (9^th-year continuous corn vs. long-term corn-soybean rotation; stover retained vs. 50% stover removed) to assess their individual and combined effects on Technology treatments and corn measurements.  On average, the combined application of advanced technologies increased corn yield by 17% over traditional farmer management, even during seasons of low yield potential. Continuous corn treatments produced, on average, 0.7 and 2.9 Mg ha^-1 less grain than corn grown in rotation in 2011 and 2012, respectively.  Partial stover removal in continuous corn systems (with advanced crop inputs) increased corn yield by 1.0 Mg ha^-1 relative to full stover retention.  Corn root biomass strongly and consistently declined (on a per-plant basis) as plant population increased.  This study provided four findings: 1) corn grain yield was greater in corn rotations relative to monoculture; 2) in continuous corn systems, partial stover removal applied in combination with advanced soil fertility inputs and advanced hybrids reduced the continuous corn yield penalty; 3) smaller corn root systems inherent at greater plant densities had to be supported with advanced fertility inputs and genetics to optimize crop productivity; and 4) nutrient use efficiency of intensively managed agronomic systems was as good as or better than traditional systems.