The study looked at how applying nitrogen to Kentucky bluegrass sod before, during, and after transplanting affects root regrowth. They found that applying nitrogen before and at the time of transplanting increased root regrowth compared to no nitrogen. Timing of nitrogen application is crucial, with applications near transplanting being most effective. Nitrogen also decreased the carbohydrate content of the grass, but this was associated with increased root regrowth. Overall, applying nitrogen at the right time can help improve the root system of transplanted sod.