Long-Term Trends of Corn Yield and Soil Organic Matter in Different Crop Sequences and Soil Fertility Treatments on the Morrow Plots

Publisher Summary The chapter describes the history of the Morrow Plots and the effects of their experimental treatments on corn yield and soil variables. Statistical analyses of the complete yield and soil organic matter (SOM) record are presented. The chapter considers the trends in response to rotation and fertility treatments applied during the main phases of the Morrow Plots' history. Yield responses simultaneously reflect changing soil productivity levels and the immediate effects of improved technology and weather. By analyzing soil variables, soil organic C, total N, pH, P, and K throughout the trial's history, the chapter explores the long-term effects of treatments on the system's productive potential. Changes in the Morrow Plots' treatments have provided an empirical basis upon which one can evaluate the several phases in agricultural history. Findings have shown that production is greater where soil condition is maintained, and that use of mineral fertilizers has offset to large extent losses in soil productivity.