Dynamic Research Of Inorganic Nitrogen In Runoff And Leaching Solution Of Sugarcane Soil

The loss of N in farmland soil is related to both economic and environmental benefits.In this study,sugarcane was used as the research object to simulate the planting of sugarcane in field to explore the dynamic process of N in soil.Six treatments were designed:1)SO:no fertilizer and no sugarcane;2)FO:no fertilizer but planting sugarcane;3)F:compound fertilizer;4)F-M:compound fertilizer + straw;5)CF:controlled release compound fertilizer;6)CF-M:controlled release compound fertilizer + straw.The main research contents are as follows:1.Under natural rainfall condition,the volume and variation characteristics of runoff and leaching water.2.Dynamic of N concentration in runoff and leaching water.3.Flux dynamics of N in runoff and leaching water among different treatments;4.Verify the simulation results of DNDC model for the dynamic process of N in sugarcane soil.The main conclusions of this study are as follows:1.The loss of inorganic nitrogen in F treatment was mainly concentrated in the two periods after application of base fertilizer and topdressing.The main form of loss of inorganic nitrogen was NO3--N,accounting for 89.35%of the total loss.Leaching was the main way of loss of inorganic nitrogen,accounting for 99.45%of the total loss.2.The loss of inorganic nitrogen in CF treatment mainly occurred within one month after application of base fertilizer,and the peak period of loss occurred again after two months.The net loss flux of inorganic nitrogen was 47.75 Kg N/hm2,and the loss rate of nitrogen fertilizer was 15.92%.The net loss flux of inorganic nitrogen in F treatment was 52.70 Kg N/hm2,and the loss rate of nitrogen fertilizer was 17.57%.There was no significant difference between the two treatments.3.The loss fluxes of inorganic nitrogen in F-M and CF-M treatments were less affected by fertilization.The net loss fluxes of inorganic nitrogen in the two treatments were-19.33 Kg N/hm2 and-21.62 Kg N/hm2,respectively.After straw mulching,the loss of inorganic nitrogen in F-M and CF-M treatments was lower than that in control F0 treatment.4.The application amount of base fertilizer in CRF treatment was three times as much as that in compound fertilizer treatment.There was no significant difference in inorganic nitrogen loss flux between the two fertilization treatments In the early stage,but the loss peak of CRF treatments appeared again after two months.There was no significant difference in loss flux between CRF treatments and compound fertilizer treatments after topdressing.The runoff and leaching water of straw mulching treatments were lower than those of other treatments,and the increase of inorganic nitrogen concentration after fertilization was lower than that of other fertilization treatments.5.DNDC model is on high side to simulate the effects of base fertilizer and top dressing,which results in higher simulation results.When inorganic nitrogen flux is low,DNDC has better fitting degree.