Can a deep-rooted spring crop recover winter-deposited nitrogen?

Grazing a winter forage crop can result in a substantial increase in soil nitrogen (N) from urine deposition, with a significant proportion being below 30 cm. If a follow-on crop can be used to recover this soil N before the following drainage season, N leaching risk could be reduced. We tested if faster growing, or deeper-rooted spring-sown crops would be more effective at recovering winter-deposited N than ryegrass based pasture. Urea-N (800 kg N/ha) was applied in June to simulate a dairy cow urine patch. In the spring, the plots were sown with ryegrass, chicory and clover, or barley. The following autumn, the amount of N in the 60-90 cm depth (70 kg N/ha) was significantly less (P<0.05) under chicory and clover than under either barley (104 kg N/ha) or pasture ryegrass (104-107 kg N/ha), suggesting that chicory was able to access the deep N pool. These data, and earlier measurements, provide evidence that chicory is a viable strategy for N recovery after winter grazing.