Side-dress N is a management strategy in maize (Zea Mays L.) production that can increase yield, reduce N leaching, and increase the probability that N remains post-flowering. This management adds cost, is time-sensitive, and can be difficult due to field shape and topography. A plantable, polymer-coated urea N bead of two sizes and two coating thicknesses was developed and field tested across multiple locations during 2015–2017 as a replacement to side-dress application. Locations differed in previous crop history and the initial N rates applied prior to treatments. Bead performance varied among locations but averaged 0.3 Mg ha⁻¹ compared to an uncoated control or in-season urea-ammonium-nitrate (UAN) application. Bead application increased yield 0.8 Mg ha⁻¹ when rainfall exceeded 225 mm between planting and R1 (silk appearance) but did not improve yield when rainfall was <125 mm. Nitrogen release from the bead was described by a thermal time function. A common exponential decay function was not adequate to describe the release of N across all locations indicating variation in release of N among locations driven by factors other than soil temperature. Slow-release, polymer-coated fertilizer, placed near the seed at planting, provides the option to apply supplemental N at planting, followed by N release later in the season, eliminating the need for in-season applications. Further research is needed to more closely match coating thickness and N release to crop N demand consistently across locations and development of equipment to enable one-pass seed planting and N application operations.

中文翻译：

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评估与玉米种子一起种植的聚合物包膜肥料原型

追施氮肥是玉米（Zea Mays L.）生产中的一项管理策略，可以提高产量，减少氮素的淋失并增加氮素在开花后的残留率。这种管理增加了成本，对时间敏感，并且由于场的形状和地形而变得困难。在2015-2017年期间，开发了一种可种植的，两种大小和两种涂层厚度的聚合物涂层尿素N珠，并在多个位置进行了现场测试，以替代便衣应用。在以前的作物历史和治疗前应用的初始氮肥施用量的位置有所不同。珠粒的性能因位置而异，但与未涂覆的对照品或季节使用的尿素-硝酸铵（UAN）相比平均为0.3 Mg ha ^-1。施用珠粒可提高产量0.8 Mg ha ^-1当种植与R1之间的降雨量超过225 mm时（丝状外观），但当降雨量<125 mm时并没有提高产量。通过热时间函数描述了从珠粒中释放出的氮。一个普通的指数衰减函数不足以描述所有位置上氮的释放，这表明除土壤温度以外的其他因素所驱动的位置之间氮的释放也有所不同。播种时将缓释，聚合物包衣的肥料放置在种子附近，提供了在播种时施用补充氮的选择，随后在季节后期释放氮，从而消除了在季节内施用的需要。需要进行进一步的研究，以使涂层厚度和氮素释放量与作物在各个地点的氮素需求一致地匹配，并开发设备以实现单次播种和氮素施用作业。