Plastic film mulching (PFM) and nitrogen (N) fertilization are two important agricultural management methods that are used to enhance crop yields in semi-arid dryland agriculture. However, the impacts of PFM and N fertilization on the temperature sensitivity (Q) of soil respiration (R), particularly its heterotrophic (R) and autotrophic (R) components, remain unclear. To investigate this, a trenching experiment was carried out between 2019 and 2021 in a rainfed maize-cultivated cropland that had been under cultivation for 7 years. There were four treatments: no PFM and N fertilization (control), full PFM without N fertilization (PFM), 150 kg N ha fertilization without PFM (Nfer), and full PFM with 150 kg N ha fertilization (PFM+Nfer). PFM and N fertilization not only enhanced crop yield and root biomass but also increased soil total respiration (R) and its components, due to improved soil hydrothermal conditions with PFM and increased N availability with N fertilization. Soil hydrothermal conditions and root biomass were identified as the most important factors influencing R and R, respectively. The greater increase in R (84 %–212 %) compared to R (9 %–29 %) resulted in a decrease in the proportion of R in R decreasing from 81.2 % in the control to 58 % under the PFM+Nfer treatment. The R/R ratio decreased in all three treatments compared to the control ( < 0.05). The increase in R under PFM led to a decrease in soil organic carbon (SOC) by 17 %. Specifically, the soil labile C content (i.e. LFOC 44 %) decreased more under PFM and PFM+Nfer ( < 0.05) compared to control, but not under the Nfer treatment ( > 0.05). Plastic film mulching increased the Q of R ( < 0.05) through decrease the content of soil labile C, whereas N fertilization had no effect ( > 0.05). Both PFM and N fertilization increased the Q of R ( < 0.05) by increasing root biomass. The impact of R’s Q (0.66) on R’s Q is greater compared to R’s Q (0.31). To our knowledge, this is the first long-term field study to examine the response of R components and their Q to PFM and N fertilization. Our results highlight that soil labile C and root biomass are the determining factors for the Q of R and R, respectively. We emphasize the importance of accurately modeling the temperature responses of R and R when predicting R under climate change scenarios.

中文翻译：

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土壤呼吸对高温和氮素有效性的温度敏感性


地膜覆盖（PFM）和施氮（N）施肥是半干旱旱地农业中用于提高作物产量的两种重要的农业管理方法。然而，PFM和施氮肥对土壤呼吸（R）的温度敏感性（Q），特别是其异养（R）和自养（R）成分的影响仍不清楚。为了调查这一问题，2019年至2021年间，在一块已经耕种了7年的雨养玉米耕地上进行了挖沟实验。共有四种处理：不施PFM和氮肥（对照）、不施氮肥的完全PFM（PFM）、不施PFM的150 kg N ha施肥（Nfer）、以及施150 kg N ha施肥的完全PFM（PFM+Nfer）。 PFM 和施氮不仅提高了作物产量和根系生物量，而且还增加了土壤总呼吸 (R) 及其组成部分，因为 PFM 改善了土壤水热条件，施氮增加了氮的有效性。土壤水热条件和根系生物量分别被确定为影响 R 和 R 的最重要因素。与 R (9%–29%) 相比，R (84%–212%) 的增加幅度更大，导致 R 在 R 中的比例下降，从对照组的 81.2% 降至 PFM+Nfer 处理下的 58%。与对照相比，所有三种处理的 R/R 比值均下降 (< 0.05)。 PFM 下 R 的增加导致土壤有机碳 (SOC) 减少 17%。具体而言，与对照相比，在 PFM 和 PFM+Nfer (< 0.05) 下土壤不稳定碳含量（即 LFOC 44%）下降更多，但在 Nfer 处理下则没有降低（> 0.05）。地膜覆盖通过降低土壤不稳定C含量提高了R的Q值（< 0.05），而施氮肥则没有影响（> 0.05）。 PFM 和氮肥均通过增加根生物量来增加 R 的 Q (< 0.05)。与 R 的 Q (0.31) 相比，R 的 Q (0.66) 对 R 的 Q 的影响更大。据我们所知，这是第一个长期实地研究，旨在检查 R 成分及其 ​​Q 对 PFM 和 N 施肥的反应。我们的结果强调，土壤不稳定碳和根生物量分别是 R 和 R Q 的决定因素。我们强调在气候变化情景下预测 R 时，准确建模 R 和 R 的温度响应的重要性。