Ammonia volatilization and yield of corn fertilized with different nitrogen sources in the Brazilian semiarid

Abstract: The objective of this work was to evaluate the effect of the use of different nitrogen fertilizers on N losses by NH3 volatilization and on the grain yield of a corn (Zea mays) crop grown in the semiarid region of the state of Sergipe, Brazil. Corn was managed under rainfed conditions and conventional tillage. The fertilization treatments were: sulfur-coated urea (SU) and organo-mineral-coated urea (OMU). Regular urea and ammonium sulfate (AS) were also included as a reference of N sources of high and low NH3-volatilization potential, as well as a control without N fertilization. The N sources were applied to the soil surface at a rate of 150 kg ha-1 N as side-dressing at the V5 growth stage of corn. The experiment was carried out in 2015 and repeated in 2016. Losses of N through NH3 volatilization differed among the N sources in the two study years, with AS presenting the lowest N losses and regular urea, the highest. In the area treated with OMU, losses by NH3 volatilization were consistently controlled, showing a reduction of 74 and 67% in relation to that of regular urea in both years. SU, however, only mitigated NH3-N losses in 2015, increasing them in 2016, compared with regular urea. Corn plant grain yield and N status, assessed by the index leaf, did not clearly reflect N losses by NH3 volatilization. For the semiarid of Sergipe, OMU is the best urea-based fertilizer to mitigate N losses by NH3 volatilization, and the use of AS is an alternative to increase corn yield and eliminate N losses as NH3.

摘要：本研究旨在评估不同氮肥施用对巴西塞尔希培州（Sergipe）半干旱地区雨养常规耕作玉米（Zea mays）田氨挥发（NH₃ volatilization）导致的氮素损失及籽粒产量的影响。供试玉米采用雨养栽培模式与常规耕作方式，施肥处理包括硫包衣尿素（sulfur-coated urea, SU）、有机矿物包衣尿素（organo-mineral-coated urea, OMU），并设置普通尿素与硫酸铵（ammonium sulfate, AS）作为高、低氨挥发潜力氮源的对照，另设不施氮肥的空白对照组。各供试氮源均于玉米V5生育期以侧施追肥方式施入土壤表面，施氮量为150 kg·ha⁻¹。试验于2015年开展，并于2016年重复进行。两年试验结果显示，不同氮源的氨挥发氮素损失存在显著差异，其中硫酸铵的氮素损失最低，普通尿素最高。有机矿物包衣尿素处理组的氨挥发损失始终得到有效控制，较普通尿素分别降低74%与67%。然而硫包衣尿素仅在2015年实现氨挥发氮损失的缓解，2016年其氨挥发损失反而高于普通尿素。通过指示叶评估的玉米籽粒产量与氮素营养状况，并未清晰反映氨挥发造成的氮素损失情况。综合来看，对于塞尔希培州半干旱区域，有机矿物包衣尿素是缓解氨挥发氮素损失的最优尿素基氮肥；而硫酸铵则可作为替代方案，在提升玉米产量的同时消除氨挥发形式的氮素损失。