In a study that spanned five years, Penn State researchers conducted intensive nitrogen monitoring in four different cropping systems designed to allow comparisons of soil nitrogen levels over time and under different organic management practices.

The researchers carried out their field-based experiment by implementing four cropping systems designed to replicate typical Pennsylvania organic feed and forage production systems. They differed from each other in terms of the cash crops and cover crops — unharvested crops planted to provide benefits such as improved soil quality and weed control — that were grown, the sequence in which they were grown, the timing and intensity of tillage operations and manure inputs.