Nitrogen and phosphorus losses from a broad paddy field in central Korea

Abstract

The present study was carried out for one year (from April 1, 1999 to March 30, 2000) to investigate the nutrient losses at a broad paddy field located at the southwest of central Korea, which is 105 ha in size. In the investigated area, the amount of rainfall was 1,236 mm during the cropping season and 156 mm in during the non-cropping season (off-season). The annual rainfall was 1,289 mm. The total amount of runoff water was 1,318 mm during the cropping season and 11 mm during the off-season and the added total amount of runoff water during the two seasons was 1,329 mm. The runoff loading of nutrients caused by runoff water was measured as follows. The amount of total-N was 6,068 kg 105 ha⁻¹ during the cropping season and 311 kg 105 ha⁻¹ during the off-season (total = 6,379 kg 105 ha⁻¹ yr⁻¹). The amount of total-P was 245 kg 105 ha⁻¹ during the cropping season and 9 kg 105 ha⁻¹ during the off-season (total = 254 kg 105 ha⁻¹ yr⁻¹). The losses of nutrients by infiltration were measured as follows. The losses of total-N, and total-P were 1,536 kg, and 7 kg 105 ha⁻¹, respectively. When the loss ratio of nutrient was calculated based on the amounts of applied chemical fertilizer, the lost nitrogen and phosphorus by runoff water were 35.11 % and 3.90 %. By infiltration water it was 8.46 % and 0.11 %, respectively.

Acknowledgments

This research was supported by the ministry of Agriculture and Forestry, Korea.