Root morphology and production are important for soil nutrient acquisition and C sequestration, but these traits are poorly understood in the bioenergy crop elephantgrass [Pennisetum purpureum (L.) Schum.]. Our objective was to characterize root traits of elephantgrass receiving different nutrient management practices in comparison with bahiagrass (Paspalum notatum Flüggé) pasture grown in the southeastern U.S. Treatments were bahiagrass + 50 kg N ha⁻¹ (BHG), and elephantgrass receiving either: 50 kg N ha⁻¹ (E50), 50 kg N ha⁻¹ + biochar (E50BC), 50 kg N ha⁻¹ + lignocellulosic fermentation residual (E50FR), or 250 kg N ha⁻¹ (E250). Roots were sampled annually for 4 yr (2013‐2016). Root C and N concentration were measured at termination (2016) of the study. Both crop species exhibited similar root length density (RLD) and root mass density (RMD) across all depths in 2014 and 2015. BHG root diameter was 55% greater than all elephantgrass treatments. By 2016, E50FR increased elephantgrass RLD and RMD in the shallow soil layers (< 0.2 m). Root N content was 15–39% lower for all elephantgrass treatments than BHG in the 0‐0.1 m depth, and 22–25% lower for E50 and E50BC in the 0.1‐ to 0.2‐m depth compared with BHG. Additionally, roots C content was 6% higher in the 0‐0.1 m compared with the 0.1‐ to 0.2‐m soil depth irrespective of treatment. Application of biochar and lignocellulosic fermentation residual as amendments produced a stimulatory effect on elephantgrass root growth in soil shallow layers, which could affect nutrient and water acquisition.

中文翻译：

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Bahiagrass牧场和象草生物能源种植系统的根系特征有所不同

根的形态和产量对于土壤养分的获取和固碳很重要，但是这些特征在生物能源作物象草[ Penisesetum purpureum（L.）Schum。]中了解甚少。我们的目标是与在美国东南部种植的Bahiagrass （Paspalum notatumFlüggé）牧草相比，采用不同养分管理方法的象草的根性状进行表征。处理为Bahiagrass + 50 kg N ha ^-1（BHG），而接受其中一种的象草为：50 kg N ha ^-1（E50），50 kg N ha ^-1 +生物炭（E50BC），50 kg N ha ^-1 +木质纤维素发酵残留物（E50FR）或250 kg N ha ^-1（E250）。每年采样4年（2013-2016年）。在研究终止时（2016年）测量根C和N浓度。在2014年和2015年，两种作物在所有深度上均表现出相似的根长密度（RLD）和根质量密度（RMD）。BHG根直径比所有象草处理大55％。到2016年，E50FR增加了浅土层（<0.2 m）中的象草RLD和RMD。与BHG相比，在0-0.1 m深度处所有象草处理的根N含量均比BHG低15-39％，在0.1-0.2 m深度处，E50和E50BC的根N含量低22-25％。此外，无论采用何种处理方法，在0-0.1 m的土壤中，根系C含量均比0.1-0.2 m的土壤深度高6％。