改性尿素硝酸铵溶液调控氮素挥发和淋溶的研究

为了提高肥料的利用率,以尿素硝酸铵溶液为原料、聚氨酸为保护剂,复合抑制剂NBPT(N-丁基硫代磷酰三胺)和DMPP(3,4-二甲基吡唑磷酸盐)为材料,开发出改性尿素硝酸铵溶液(YUL1和YUL2),研究其对华北平原夏玉米追肥过程中的氨挥发和淋溶损失的调控效果。田间试验设置6个处理:不施氮肥(CK)、农民习惯追施尿素(CN)、优化追施尿素(CNU)、优化追施尿素硝酸铵溶液(UAN)、优化追施改性尿素硝酸铵溶液(YUL1)和优化追施改性尿素硝酸铵溶液(YUL2)。采用扫描电镜和能谱仪分析相关指标变化,在夏玉米喇叭口期追施氮肥后15d内进行田间原位连续动态观测氨挥发和土壤铵态氮和硝态氮变化,并在玉米成熟期测定产量,计算经济效益。结果表明,改性尿素硝酸铵溶液清澈无杂质,流延后成膜表面光滑、致密,抑制剂在膜表面分布均匀;能谱测试膜层表面磷硫含量增高,证明复合抑制剂与尿素硝酸铵溶液达到有效融合。在同等优化施氮量下:与CNU相比, YUL1氨挥发总量显著降低19.3%, YUL2增加9.6%;与UAN相比, YUL1、YUL2分别显著降低57.3%和42.0%。与其他施氮处理相比, YUL1和YUL2夏玉米季生长中后期0～20 cm土层依然保持相对较高的氮素含量水平,夏玉米收获后土壤硝态氮含量分别比CNU高46.0%和43.4%,比UAN高45.6%和44.7%;180～200cm土层硝态氮含量显著低于其他处理。在保证产量和净收益的同时,改性尿素硝酸铵肥料显著降低了氮素的氨挥发和淋溶损失浓度,尿酶抑制剂含量相对较高的YUL1抑制氨挥发的效果更好,硝化抑制剂含量相对高的YUL2硝态氮向下淋失的风险更小。

Effects of modified urea ammonium nitrate solution topdressing on ammonia volatilization and leaching

In this study, with urea ammonium nitrate solution as raw material, NBPT (n-butyl thiophosphoric triamide) and DMPP (3,4-dimethylpyrazole phosphate) were used as inhibitors, and polyurethane as a protective agent to develop two modified urea ammonium nitrate solutions (YUL1 and YUL2). And their effects on ammonia volatilization and leaching loss in summer maize in the North China Plain were studied. In the field experiment, six treatments were set up: 1) no urea application (CK), 2) farmers'' traditional urea application (CN), 3) optimized urea application (CNU), 4) application of optimized urea ammonium nitrate solution (UAN), 5) and 6) optimized modified urea ammonium nitrate solution 1 (YUL1) and 2 (YUL2) application. The effects of nitrogen regulation characteristics were systematically evaluated. The properties of the products were analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). The in-situ continuous dynamic observation of ammonia volatilization and nitrogen transformation was carried out within 15 days after nitrogen application (which occurred at bell mouth stage of summer maize); the yield and economic benefits were measured and calculated at the maturity stage of maize. The results showed that the modified urea ammonium nitrate solution was clear and free of impurities, the film surface was smooth and dense after casting, and the inhibitors were evenly distributed on the film surface. The content of phosphorus and sulfur on the film surface was increased by energy spectrum test, which proved that the composite inhibitors and urea ammonium nitrate solution achieved effective fusion. Under the same optimized nitrogen application rate, compared with CNU, the total amount of ammonia volatilization of YUL1 decreased significantly by 19.3% and YUL2 increased by 9.6%. Compared with UAN, YUL1 and YUL2 decreased the total amount of ammonia volatilization significantly by 57.3% and 42.0%, respectively. Compared with other nitrogen application treatments, the soil layer of 0-20 cm in the middle and late period of summer maize growth of YUL1 and YUL2 treatments still maintained relatively higher nitrogen contents. After harvest, the soil nitrate nitrogen contents of YUL1 and YUL2 were 46.0% and 43.4%, respectively, higher than that of CNU, and 45.6% and 44.7% higher than that of UAN in the 0-20 cm soil layer; in the soil layer of 180-200 cm, they were significantly lower than those of other treatments. With regard to ensuring the yield and net income of summer maize, the modified urea ammonium nitrate solution significantly reduced ammonia volatilization and leaching loss of nitrogen.