Characterization of Mollisols after Long-Term N Fertilization at Successive Rates in Continuous and Rotated Corn Systems

Modern agricultural systems rely on inorganic nitrogen (N) fertilization to enhance crop yields, but its overuse may negatively impact soil properties. Soil properties a depth of 90 cm were studied after 36 years N at successive rates 0, 202, and 269 kg ha?1 (N0, N202, N269) in continuous corn production [Zea mays L.] (CCC), the (Cs) soybean [Glycine max (L.) Merr.] (Sc) phases corn-soybean (CS) rotation. Experimental plots arranged as split-plot randomized complete block design with three replications. High levels under CCC acidified topsoil (N0 pH 6.6 vs. N269 4.9), increased nitrate level eight-fold compared unfertilized controls. Under CCC, N0 had more than twice available phosphorus (P) 40% potassium (K) fertilized soils. Though treatments did not organic carbon (SOC) content, water aggregate stability (WAS) decreased during phase rotated treatment when CCC. Fertilization affected bulk density (BD), which by 5% from across rotations. Averaged since start study, yields 60% fertilizer use controls (N0). The grain yield benefited rotation soybeans rendering 17% Cs Yet this benefit rose 45% average, no was used Cs. Our results showed that there are important trade-offs long-term monocultures, use, even fertile resilient soils Midwestern U.S., has led P K depletion, acidification, potentially exacerbated losses environment.