Effects of green manure incorporation combined with nitrogen fertilizer reduction on soil respiration and its temperature sensitivity for wheat fields
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摘要: 研究绿肥还田结合氮肥减施对麦田土壤呼吸动态及小麦产量的影响, 以期为干旱绿洲灌区农田碳减排技术研发提供理论依据。试验于2021—2022年在甘肃河西绿洲灌区开展, 以常规施氮无绿肥还田(N100)为对照, 设施用15 000 kg∙hm−2绿肥+85%氮肥(G1N85)、22 500 kg∙hm−2绿肥+85%氮肥(G2N85)、30 000 kg∙hm−2绿肥+85%氮肥(G3N85)、15 000 kg∙hm−2绿肥+70%氮肥(G1N70)、22 500 kg∙hm−2绿肥+70%氮肥(G2N70)和30 000 kg∙hm−2绿肥+70%氮肥(G3N70)共7个处理。探讨小麦生育期的土壤呼吸速率、碳排放量、产量及碳排放效率, 分析土壤呼吸对土壤温度的响应。结果表明: 不同处理下麦田土壤呼吸速率均呈先升高后降低的单峰趋势, 全生育期内变化范围为0.8~6.2 μmol∙m−2∙s−1。绿肥还田结合氮肥减施显著提高麦田土壤呼吸速率及土壤CO2排放总量, 与N100相比, 其平均增幅分别为6.7%~16.5%和5.4%~15.8%; 其中G3N85和G3N70较其他处理土壤呼吸速率分别增加2.2%~13.8%和3.2%~16.5%, 土壤CO2排放总量分别增加2.8%~13.2%和3.0%~15.8%; 与G3N85相比, G3N70处理两年平均土壤呼吸速率及土壤CO2排放总量分别增加3.2%和3.0% (P<0.05)。绿肥还田结合氮肥减施处理显著降低土壤呼吸温度敏感性(Q10), 与N100相比, Q10值降幅为10.4%~18.1% (P<0.05)。绿肥还田结合氮肥减施显著影响了小麦产量和土壤碳排放效率, 其中G3N85处理分别显著高于其他处理4.0%~31.3%和0.3%~20.9% (P<0.05)。可见, 绿肥还田结合氮肥减施在增强麦田土壤呼吸的同时, 显著降低土壤呼吸温度敏感性, 提高小麦产量和碳排放效率, 其中翻压绿肥30 000 kg∙hm−2配合氮肥减量15%处理(G3N85)是河西绿洲灌区小麦田节氮减排和提高农田土壤生产力的有效途径。Abstract: This study was conducted to explore the effects of green manure incorporation combined with nitrogen fertilizer reduction on soil respiration dynamics of wheat fields and wheat yield in oasis irrigation area, in order to provide a theoretical basis for the study of carbon emission reduction in farmland in arid oasis irrigation area. The experiment was conducted from 2021 to 2022 in the Hexi oasis irrigation area. With the conventional nitrogen application without green manure (N100) as control, setting the following treatments include 15 000 kg∙hm−2 green manure + 85% nitrogen fertilizer (G1N85), 22 500 kg∙hm−2 green manure + 85% nitrogen fertilizer (G2N85), 30 000 kg∙hm−2 green manure + 85% nitrogen fertilizer (G3N85), 15 000 kg∙hm−2 green manure + 70% nitrogen fertilizer (G1N70), 22 500 kg∙hm−2 green manure + 70% nitrogen fertilizer (G2N70) and 30 000 kg∙hm−2 green manure + 70% nitrogen fertilizer (G3N70) for seven treatments in total. The study was explored the soil respiration rate, carbon emissions, yield and carbon emission efficiency during the growth period of wheat, and analyzed the response of soil respiration to soil temperature. The results showed that the soil respiration rate under different treatments showed a single-peak trend of initially increasing and then decreasing, and the variation range was 0.8 to 6.2 μmol∙m−2∙s−1 during the whole growth period. The combination of green manure incorporation and nitrogen fertilizer reduction significantly increased the soil respiration rate and the total soil CO2 emissions of wheat fields, compared with N100, the average increases were 6.7% to 16.5% and 5.4% to 15.8%, respectively, in which G3N85 and G3N70 increased soil respiration rate by 2.2% to 13.8% and 3.2% to 16.5% compared with other treatments, and the total soil CO2 emissions increased by 2.8% to 13.2% and 3.0% to 15.8%, respectively(P<0.05). Compared with G3N85, the average soil respiration rate and total soil CO2 emissions of G3N70 treatment increased by 3.2% and 3.0%, respectively (P<0.05). Green manure incorporation combined with nitrogen fertilizer reduction significantly decreased the temperature sensitivity of soil respiration(Q10), and compared with N100, Q10 values decreased by 10.4% to 18.1% (P<0.05). Green manure incorporation combined with nitrogen fertilizer reduction could significantly affect wheat yield and soil carbon emission efficiency, with the G3N85 treatment significantly higher than other treatments by 4.0% to 31.3% and 0.3% to 20.9%, respectively (P<0.05). In conclusion, green manure incorporation combined with nitrogen fertilizer reduction enhanced soil respiration of wheat fields while reducing the temperature sensitivity of soil respiration, and improving wheat yield and carbon emission efficiency, of which green manure incorporation at 30 000 kg∙hm−2 combined with nitrogen fertilizer reduction by 15% (G3N85) proved to be an effective way for nitrogen reduction and emission mitigation and improve soil productivity for wheat fields in Hexi oasis irrigation area.
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图 3 2021—2022年绿肥还田结合氮肥减施条件下土壤呼吸速率季节变化规律
2021年小麦苗期、拔节期、孕穗期、开花期、灌浆期、成熟期对应测定土壤呼吸速率日期为4月25日、5月12日、5月28日、6月14日、6月29日、7月13日; 2022年各测定时期对应日期为5月2日、5月19日、6月2日、6月18日、7月2日、7月18日; 图中误差线表示LSD值。
Figure 3. Seasonal variation of soil respiration rate under green manure incorporation combined with nitrogen fertilizer reduction from 2021 to 2022
The determining dates for measuring soil respiration rate were 25 April, 12 May, 28 May, 14 June, 29 June, and 13 July in 2021, and 2 May, 19 May, 2 June, 18 June, 2 July, and 18 July in 2022. The corresponding growing stages of wheat were seeding, jointing, booting, flowering, filling, harvesting stage, respectively; Error bar indicates the value of LSD in the figure.
表 1 不同试验处理的绿肥翻压量与氮肥施用量
Table 1. Green manure incorporation and nitrogen fertilizer application in different experimental treatments
处理
Treatment施氮量
N application
rate (kg∙hm−2)绿肥还田量
Amount of Vicia villosa
incorporation (kg∙hm−2)N100 180 0 G1N85 153 15 000 G2N85 153 22 500 G3N85 153 30 000 G1N70 126 15 000 G2N70 126 22 500 G3N70 126 30 000 此处绿肥还田量为鲜重, G1、G2和G3按平均85%含水量计算其干重投入量分别为2250 kg hm−2、3375 kg hm−2和4500 kg hm−2。The amount of green manure is expressed as fresh weight, the dry weight of G1, G2 and G3 are 2250 kg hm−2, 3375 kg hm−2 and 4500 kg hm−2 according to the average water content of 85%, respectively. 表 2 2021—2022年绿肥还田结合氮肥减施条件下小麦产量及碳排放效率
Table 2. wheat yield and carbon emission efficiency under green manure incorporation combined with nitrogen fertilizer reduction from 2021 to 2022
处理
Treatment籽粒产量
Grain yield (kg∙hm−2)碳排放效率
Carbon emission
efficiency (kg∙kg−1)2021 2022 2021 2022 N100 6227.0±136.6 e 6222.6±124.1 e 2.3 c 2.3 c G1N85 6874.6±198.0 d 7302.6±128.8 cd 2.4 bc 2.5 b G2N85 8986.8±282.6 a 8411.4±279.0 b 3.0 a 2.8 a G3N85 9250.4±77.9 a 8871.4±269.0 a 3.0 a 2.8 a G1N70 7138.7±49.84 d 6957.8±144.5 d 2.4 b 2.4 bc G2N70 7483.9±108.0 c 7478.9±88.9 c 2.4 b 2.5 b G3N70 7816.0±121.4 b 8081.1±339.1 b 2.4 b 2.5 b 同列数据后不同小写字母表示处理间在P<0.05水平差异显著。Values followed by different lowercase letters in a column are significantly different at P<0.05 probability level. -
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