Abstract Biochar produced from low-value juniper was evaluated for its utility in improving restoration of native bunchgrasses. We hypothesized that biochar could expand the window of favorable conditions for seedling establishment by slowing soil drying. In a greenhouse study, applications of biochar on the soil surface were compared to incorporation of biochar, and improvements in water content, germination, and seedling survival were evaluated. Underlying hydraulics were investigated with measurements of soil and biochar water retention and Hydrus-1D simulations. The greenhouse study showed that applying any depth of biochar on top of soil was not effective at improving soil water content, and furthermore inhibited germination of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love). In contrast, mixing biochar into soil significantly slowed initial soil drying and increased seedling biomass by 70% compared to unamended soil. However, moisture benefits of biochar incorporation were temporary and, as the soil dried, the treatment with incorporated biochar lost more water than soil that was unamended, because biochar increased unsaturated hydraulic conductivity. Model simulations of the experimental conditions similarly showed that incorporating biochar improved early soil water content, but also suggested that this result was specific to the drainage conditions of pots and may not translate to a deeper soil. Model simulations also supported the idea that biochar applied as a mulch could have an increasing benefit over time by reducing evaporation. This study suggested that both incorporation and mulch application of biochar may benefit seedling establishment, but further investigations in a naturally-draining soil are needed to validate these findings.

中文翻译：

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生物炭作为地表覆盖物是否有利于草地恢复？

摘要 评价了从低价值杜松生产的生物炭在改善原生丛草恢复方面的效用。我们假设生物炭可以通过减缓土壤干燥来扩大幼苗建立的有利条件窗口。在温室研究中，将生物炭在土壤表面的应用与生物炭的掺入进行了比较，并对含水量、发芽和幼苗存活率的改善进行了评估。通过测量土壤和生物炭保水性以及 Hydrus-1D 模拟，研究了潜在的水力学。温室研究表明，在土壤顶部施用任何深度的生物炭都不能有效提高土壤含水量，而且还会抑制蓝束小麦草（Pseudoroegneria spicata [Pursh] A. Love）的萌发。相比之下，与未改良的土壤相比，将生物炭混合到土壤中显着减缓了初始土壤干燥并使幼苗生物量增加了 70%。然而，掺入生物炭的水分益处是暂时的，随着土壤干燥，掺入生物炭的处理比未经改良的土壤损失更多的水分，因为生物炭增加了不饱和导水率。实验条件的模型模拟同样表明，加入生物炭改善了早期土壤的含水量，但也表明该结果特定于盆的排水条件，可能不会转化为更深的土壤。模型模拟还支持这样一种观点，即生物炭作为覆盖物可以通过减少蒸发随着时间的推移而获得越来越大的好处。