关键词: 平原河网区, 棉田, 地表径流, 磷素, 负荷, EMC

Abstract: Phosphorus loss from the farmland at the surface runoff plot scale (60 m²) and the field scale (10 hm²) with surface runoff was investigated in a plain river network region typical of North Jiangsu Province through two years of field observation. The fields were cultivated with upland crops, like cotton, rape, maize, and soybean crops, separately. Results show that the total phosphorus load in surface runoff from the plot cultivated with cotton was 356.60 g/hm2 and 290.28 g•hm² in 2009 and 2010, respectively, higher than those from the plots cultivated separately with maize, soybean and rapeseed, that is, 169.08, 192.20 and 128.74 g•hm², respectively, in 2010. During the two years of field observation, a total of 11 field-scaled rain-triggered runoff events were observed. Of the 11 events, the average total phosphorus load in surface runoff was 50.66 g•hm² and the mean concentration of total phosphorus in surface runoff was 0.23 mg•L^-1. They were higher from fields than from plots. Rainfall, farmland cultivation and management practices, irrigation-drainage ditch distribution were the main factors affecting phosphorus loss with surface runoff in the plain river network region.

Key words: plain river network region, cotton field, surface runoff, phosphorus, load, EMC