Paulownia is a well-known, fast-growing tree genus that is widely planted for commercial cultivation in the warm temperate zone of the North China Plain. Fertilization as a standard practice can efficiently increase wood production and tree yield in those Paulownia plantations, but how different fertilization measures might affect soil microbial activity, microbial biomass and metabolic functioning unclear, especially in the subtropics. To fill this knowledge gap, we initiated long-term different fertilization experiments from afforestation, using a completely randomized block design consisting of a control, inorganic fertilizer, microelement-inorganic fertilizer and organic–inorganic compound fertilizer (OIF) treatments in South China's subtropical zone. The results revealed fertilization significantly increased soil enzyme activity and microbial biomass, especially that of urease, invertase, acid phosphatase, as well as the microbial biomass in terms of carbon and nitrogen, all of which increased most significantly in soil under the OIF treatment. The carbon source utilization levels of five carbon substrates under the OIF treatment, namely D-xylose, glucose-1-phosphate, D-cellobiose, α-ketobutyric acid and glycogen, were significantly higher than those of the others. From these data, we may reasonably infer that the application of organic fertilizer could offer an effective management practice for use in Paulownia plantations. The five carbon matrices may be the most efficient carbon sources for increasing the abundance of efficient soil microorganisms, improving soil fertility and achieving the sustainable development of Paulownia plantations.

中文翻译：

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长期施肥对泡桐林土壤微生物活性及代谢的影响

泡桐是著名的速生树种，在华北平原暖温带地区广泛种植用于商业种植。施肥作为一种标准做法可以有效地增加那些泡桐的木材产量和树木产量种植园，但不同的施肥措施如何影响土壤微生物活动、微生物生物量和代谢功能尚不清楚，尤其是在亚热带地区。为了填补这一知识空白，我们在华南亚热带地区使用由对照、无机肥、微量元素-无机肥和有机-无机复合肥（OIF）处理组成的完全随机区组设计，开展了与造林不同的长期施肥试验。 . 结果表明，施肥显着增加了土壤酶活性和微生物生物量，尤其是脲酶、蔗糖酶、酸性磷酸酶以及碳和氮方面的微生物生物量，所有这些在OIF处理下土壤中的增加最为显着。α-酮丁酸和糖原显着高于其他。从这些数据中，我们可以合理地推断，有机肥的施用可以为泡桐种植园提供有效的管理实践。这五种碳基质可能是增加高效土壤微生物丰度、提高土壤肥力和实现泡桐人工林可持续发展的最有效碳源。