施氮对黄土旱塬区春玉米土壤呼吸和温度敏感性的影响

Effects of Nitrogen Fertilization on Soil Respiration and Temperature Sensitivity in Spring Maize Field in Semi-Arid Regions on Loess Plateau

了解施氮对土壤呼吸和温度敏感性的影响,是研究农田土壤呼吸变化的重要环节,对预测农田土壤呼吸变化具有重要意义.基于中国科学院长武黄土高原农业生态试验站的氮肥管理试验,于2013年4月至2014年9月利用LI-8100系统(LICOR,Lincoln,NE,USA)监测施氮和不施氮条件下旱地春玉米生长季土壤呼吸、温度、水分以及根系生物量的变化,研究施氮条件下生物与非生物因素对土壤呼吸速率和温度敏感性(Q10)的影响.施氮显著提高了生长季土壤的累积呼吸量(P<0.05),与不施氮相比,施氮处理累积呼吸量2013年提高了35%,2014年提高了54%.但施氮显著降低了土壤呼吸温度敏感性(P<0.05),施氮处理的Q10较对照2013年降低了27%,2014年降低了17%.施氮显著提高了春玉米产量、地上部生物量和根系生物量(P<0.05).施氮处理根系生物量较不施氮处理2013年提高了0.32倍,2014年提高了1.23倍.施氮对土壤温度和水分无显著影响,根系生物量是施氮条件下导致土壤呼吸差异的重要生物因素.

Understanding the effects of nitrogen fertilization on soil respiration rate and its temperature sensitivity ( Q10 ) is of critical importance to predict the variability of soil respiration in cropland. A field experiment was established in a rain-fed spring maize cropland (Zea mays L. ) in the State Key Agro-Ecological Experimental Station in the Loess Plateau in Changwu County, Shaanxi Province, China. The experiment comprised of two treatments: no N-fertilizer application (CK) and N-fertilizer application with 160 kg N?hm - 2 (N). Soil respiration rate, soil temperature, soil moisture, yields, aboveground biomass and root biomass were measured in two continuous spring maize growing seasons from April 2013 to September 2014. The cumulative soil CO2 emissions were increased by 35% in 2013 and 54% in 2014 in N treatment as compared to CK treatment. Though nitrogen fertilization significantly increased the cumulative soil CO2 emissions (P ﹤ 0. 05), it did decrease evidently the temperature sensitivity of soil respiration (P ﹤ 0. 05). The Q 10 values in N treatment were decreased by 27% and 17% compared with CK treatment in 2013 and 2014, respectively. Nitrogen fertilization significantly increased the maize yields, aboveground biomass and root biomass (P ﹤ 0. 05). Root biomasses in N treatment were 32% and 123% greater than those in CK treatment of 2013 and 2014, respectively. Nitrogen fertilization had no marked influence on soil temperature or moisture. Root biomass was a critical biotical factor for variation of soil respiration under nitrogen fertilization.