Effects of Reducing Nitrogen and Biomass Carbon Fertilization on Loss of Nitrogen and Phosphorus in Surface Water of Paddy Field and Grain Production

The influence of fertilizer of reducing nitrogen and biomass carbon on loss risk of nitrogen and phosphorus in surface water of paddy field and paddy character was studied.The results showed that the concentration of total nitrogen,soluble nitrogen and ammonium nitrogen in surface water of paddy field with different fertilization treatments all reached the highest on the second day after fertilization,then fell rapidly,and tended to be stable a week later.The stable concentration increased by 5.6%～16.3%,8.4%～23.7% and 25.0%～46.1%compared to the peak concentration.Total phosphorus concentration in surface water of paddy field with different fertilization treatments reached the highest on the third day after fertilization,then fell rapidly,and tended to be stable a week later.Soluble phosphorus concentration stayed a steady state in 4 ～5dafter fertilization,then gently fell to the value before fertilization.Nitrogen and phosphorus concentration of reducing nitrogen(20%)fertilizer were lower than that of normal fertilization.Reducing nitrogen fertilizer had little influence on grain production,but the treatment of reducing nitrogen fertilizer combined biomass carbon increased the production by 24.6%compared with normal fertilization,with the production reached to 7 391.5kg/hm2.Reducing nitrogen fertilizer reduced the risk of nitrogen loss,but combined biomass carbon obviously improved total phosphorus concentration in the surface water of paddy field,and increased the risk of phosphorus loss.The best period of controlling nitrogen and phosphorus loss was in a week after fertilization.If encountering rainstorm at this time,it would lead to loss of nitrogen and phosphorus with runoff.