不同缓/控释尿素对小麦生长及氮素利用的影响

  【目的】   通过大田试验筛选山东省适宜于小麦生长的缓/控释尿素，并初步研究其氮素高效利用的机制。   【方法】   选用的肥料产品有4种，包括树脂包膜尿素 (PCU)、多肽尿素 (PPU)、脲甲醛尿素 (UF) 和本实验室制备的树脂包膜与脲酶抑制剂结合型控释尿素 (CHQ)，以普通尿素和不施氮肥为对照，分别在山东潍坊和泰安进行田间试验，供试小麦品种为‘济麦22号’，普通尿素按1∶1比例基施和追施，缓/控释肥均一次性基施。分析了小麦不同时期的株高和单株分蘖数、花前花后干物质积累与转运、产量及其构成因素、氮肥利用率以及土壤无机氮含量和脲酶活性的变化。   【结果】   施用4种缓/控释尿素均降低了小麦越冬期的土壤脲酶活性，减缓尿素水解，降低土壤无机氮含量；成熟期，在潍坊试验点仅CHQ处理的土壤无机氮含量高于尿素处理，在泰安试验点4种缓/控释尿素处理的土壤无机氮含量均高于尿素处理，以CHQ处理的无机氮含量最高，CHQ处理的土壤无机氮含量在泰安和潍坊2个试验点较尿素处理分别增加了81.86%和6.20%。与尿素相比，在泰安试验点施用4种缓/控释尿素均可促进小麦生长，提高小麦花前干物质转运与花后干物质生产量，有利于小麦的群体构建和产量形成，增强小麦对氮素的吸收利用能力，提高氮肥利用率，以CHQ表现最优；而在潍坊试验点，仅CHQ肥效优于尿素。CHQ在泰安和潍坊的小麦产量分别为6966.67和10342.22 kg/hm2，较尿素处理分别增加了38.69%和11.07%；氮素生产效率分别为18.83和26.72 kg/kg，较尿素处理分别增加了38.66%和11.06%。潍坊试验点小麦产量和氮素生产效率整体高于泰安，CHQ较尿素的增效幅度低于泰安试验点。   【结论】   土壤肥力影响缓/控释尿素对小麦的增产效果，在高肥力的壤土 (潍坊) 上，只有既控制尿素释放速率又控制其在土壤中的水解速率的树脂包膜与脲酶抑制剂结合型控释尿素可有效促进小麦生长及其对氮素的吸收利用，在低肥力砂壤土 (泰安) 上，4种缓/控释尿素在小麦生长后期均可维持土壤中较高的氮素供应，肥效均好于普通尿素。综合而言，在山东省建议优先选择树脂包膜与脲酶抑制剂结合型控释尿素。

Effects of different slow/controlled release urea on wheat growth and nitrogen utilization

  【Objectives】   This study compared the effects of slow/controlled release urea products on wheat growth and nitrogen use efficiency in Shandong Province. The aim was to provide a reference for choosing suitable urea products in wheat production.   【Methods】   Field experiments were conducted in Tai’an and Weifang cities, representing two the main winter wheat production areas in Shandong Province. We used ‘Jimai 22’ as wheat test cultivar to investigate the effects of four slow/controlled release urea products: resin-coated urea (PCU), peptide urea (PPU), urea-formaldehyde urea (UF), and self-made resin coating combined with urease inhibitor to control the release of urea (CHQ), and common urea and no fertilizer as controls. One time of application was used for the four slow/controlled release urea products, and twice of applications was used for the control urea with ratio of 1∶1 for basal and topdressing. We investigated the plant height, tillering traits, dry matter accumulation and transportation, yield and yield components, and nitrogen use efficiency of wheat. The soil available nitrogen content and urease activity were measured at wintering, greening, jointing, flowering, and mature stages.   【Results】   All the slow/controlled release urea treatments reduced the soil urease activity in wintering stage of wheat growth, slowed down the hydrolysis of urea, and reduced soil available nitrogen content. At the maturity stage in Weifang, only CHQ had higher soil available N content than urea control, while in Tai’an, all the slow/controlled release urea treatments had higher soil available N than urea control. The soil available N content in CHQ treatment in Tai’an and Weifang increased by 81.86% and 6.20% than the control, respectively. Compared with the control in Tai’an, all four slow/controlled releases of urea treatments promoted wheat growth, dry matter transport before flowering, and dry matter production after flowering, thereby benefiting population construction and yield formation and enhancing N absorption and utilization. The wheat yield in CHQ treatment in Tai’an (6966.67 kg/hm2) and Weifang (10342.22 kg/hm2) (P < 0.05) were increased by 38.69% and 11.07%, respectively, and N production efficiency (18.83 kg/kg and 26.72 kg/kg) increased by 38.66% and 11.06%, respectively, compared to the urea control. The yield and N production efficiency in Weifang was higher than in those Tai’an, but the increase rate in CHQ treatment was opposite.   【Conclusions】   Slow/controlled release urea products have different wheat production efficiencies in Shandong Province. In high fertility loam soil of Weifang, the urea product that could control the release and hydrolysis of nitrogen product in the soil (CHQ) was effective, while in low fertility sandy soil of Tai'an, all the four slow/controlled release urea could maintain a high nitrogen supply in the later stage of wheat growth, and N fertilization efficiency outweighs that in control. Therefore, urea product with resin coating and urease inhibitor is recommended for improving wheat production in Shandong Province.