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采用野外定位观测试验,研究巢湖流域不同耕作和施肥方式下农田养分径流流失特征,探索降低养分流失、提高湖区水质的有效耕作和施肥措施。2009-2010年结果表明,冬季麦田径流液总氮(TN)的浓度范围是2.12～4.34mg/L,溶解态氮(DN)约占TN的72%～92%,DN中又以硝态氮(NO3--N)为主,溶解态有机氮(DON)次之,铵态氮(NH4+-N)所占比例极小。径流液总磷(TP)浓度范围是0.095～0.360mg/L,颗粒态磷(PP)约占TP的51%～69%。DN和PP是农田氮磷径流流失的主要形态。长期的保护性耕作可提高径流液TN、DN、NO3--N、DON和DP的浓度,降低PN和PP的浓度,但对NH4+-N和TP浓度无明显影响;氮肥后移一定程度上易增加追肥后短期内降雨径流液各形态N的浓度,但可降低小麦整个生育期内径流液各形态P的浓度。在当地常规耕作条件下(处理CT),麦田TN和TP径流流失量分别为1.065,0.079kg/hm2,占当季施N量的0.71%,施P量的0.24%。与处理CT相比,处理CTS(常规+覆盖)、NFP(氮肥后移)和NTS+NFP(少免耕覆盖+氮肥后移)TN流失量分别减少了14%、21%和24%,TP流失量分别减少了20%、21%和24%。因此,保护性耕作和氮肥后移在保证小麦产量的前提下,可作为巢湖流域源头控制农田养分流失的主要措施。
The field experiment was conducted to study the characteristics of runoff loss of farmland under different tillage and fertilization regimes in Chaohu Lake Basin, and to explore effective tillage and fertilization measures to reduce nutrient loss and improve water quality in the lake. The results of 2009-2010 showed that the concentration of total nitrogen (TN) in winter wheat runoff was 2.12 ~ 4.34 mg / L and the dissolved nitrogen (DN) accounted for 72% ~ 92% of TN. The content of nitrate nitrogen (NO3 - N), dissolved organic nitrogen (DON) followed by ammonium nitrogen (NH4 + -N) accounted for a very small proportion. Runoff fluid total phosphorus (TP) concentration range of 0.095 ~ 0.360mg / L, particulate phosphorus (PP) accounted for about 51% of TP ~ 69%. DN and PP are the main forms of runoff loss of nitrogen and phosphorus in farmland. Long-term conservation tillage increased the concentration of TN, DN, NO3 - N, DON and DP in runoff and decreased the concentration of PN and PP, but had no significant effect on the concentrations of NH4 + -N and TP; Increase the concentration of various forms of rainfall runoff in the short term after top dressing, but reduce the concentrations of various forms of runoff in wheat throughout the growth period. The runoff losses of TN and TP in wheat field were 1.065 and 0.079 kg / hm2, respectively, accounting for 0.71% and 0.24% of the application amount of N in the field under conventional tillage conditions (treatment of CT). Compared with the treatment of CT, the TN loss of treatment CTS (routine + cover), NFP (nitrogen removal) and NTS + NFP (reduction of no tillage and nitrogen removal) decreased by 14%, 21% and 24% The loss was reduced by 20%, 21% and 24% respectively. Therefore, under the premise of conservation yield and wheat yield, conservation tillage and post-N recovery can be the main measures for controlling the nutrient loss of farmland at the source of the Chaohu Lake Basin.