Nitrogen (N) from fertilizer and manure application is lost when the corn and soybean crops are unable to use all the nitrogen in the soil.
During rainfall, unused nitrogen leaches down through the soil profile becoming inaccessible to crops and then leaves the field through tile lines. Nitrogen is lost in a similar way on non-tiled land. On non-tiled land, nitrogen enters shallow groundwater and seeps into local creeks and streams. This loss occurs mostly in the spring. Nitrogen loss is primarily a result of mismatched timing, having nitrogen present in the soil at times when the crop can’t take it up and when rain is likely to occur.