3种土壤改良剂对河套灌区玉米田温室气体排放的影响

为研究膨润土、生物炭和聚丙烯酸钾等土壤改良剂对农田温室气体排放的影响,采用静态暗箱-气相色谱法研究了5种不同施肥处理(不施肥、常规施肥、常规施肥+膨润土、常规施肥+生物炭、常规施肥+聚丙烯酸钾,分别标记为NF、CK、B、C和PAM)下河套灌区2015、2016两年玉米田温室气体排放动态变化.结果表明,玉米生育期内,河套灌区农田N_2O呈双峰型排放规律,各处理于追肥灌水后5~7 d出现N_2O排放峰值;农田CH_4排放无明显规律,个别处理于追肥灌水后6 d左右出现CH_4排放峰值,其余时期均表现为土壤对CH_4的吸收作用;CO_2呈单峰型排放规律,于玉米拔节期出现排放峰值.相关性分析表明,土壤温度的升高,可显著增加土壤N_2O和CO_2的排放速率.与CK相比,B和PAM处理可显著降低N_2O累计排放量(P0.05),降幅分别为38.59%和45.35%;B、C处理可显著增强土壤对CH_4的吸收作用(P0.05),累计吸收量分别增加144.44%和172.22%;B、C处理CO_2累计排放量与CK差异显著(P0.05),与CK相比分别降低25.40%和22.21%.总体来说,B、C和PAM处理下综合增温潜势较CK分别降低27.77%、19.61%和12.16%,温室气体排放强度降低35.20%、26.65%和13.36%.与CK相比,B、C处理下玉米产量显著提高11.33%和9.59%,净生态系统经济预算显著增加16.15%和12.65%(P0.05).综上所述,对河套灌区玉米种植体系而言,常规施肥基础上添加膨润土、生物炭是提高作物产量、降低增温潜势的有效农业措施.

Effects of Three Soil Amendments on Greenhouse Gas Emissions From Corn Fields in the Hetao Irrigation District

In order to study the effects of soil amendments on greenhouse gas emissions, five different fertilization treatments (no fertilization, conventional fertilization, conventional fertilization+bentonite, conventional fertilization+biochar, and conventional fertilization+potassium polyacrylate, labeled as NF, CK, B, C, and PAM) were applied on corn fields in the Hetao irrigation district during the maize growing seasons of 2015 and 2016, and the samples were analyzed by static chamber-gas chromatography. The results showed that N₂O had a bimodal emission pattern in the Hetao Irrigation Area, and the N₂O emission peak appeared five to seven days after topdressing and irrigating (d.p.ti). The CH₄ emission had no apparent pattern. While the CH₄ emission peak appeared with a few treatments after 6 d.p.ti, the rest of the period indicated the CH₄ absorption in the soil. CO₂ had a unimodal emission pattern, and the CO₂ emission peak appeared during the jointing stage of maize growth. In addition, the correlation analysis indicated that an increase in soil temperature could significantly increase the N₂O and CO₂ emission rates. Moreover, compared with the CK treatment, the B and PAM treatments could significantly decrease the cumulative emission of N₂O (P<0.05), with a decline of 38.59% and 45.35%, respectively. The B and C treatments could significantly enhance the soil uptake of CH₄ (P<0.05), and the cumulative absorption of CH₄ increased 144.44% and 172.22%, respectively. The B and C treatment results were significantly different from the CK treatment based on the cumulative emission of CO₂ (P<0.05), with a decrease of 25.40% and 22.21%, respectively. In general, compared with the CK treatment, the comprehensive warming potential of the B, C, and PAM treatments declined by 27.77%, 19.61%, and 12.16%, respectively. The greenhouse gas emission intensity of the B, C, and PAM treatments decreased by 35.20%, 26.65%, and 13.36%, respectively. The maize yield with the B and C treatments was significantly increased by 11.33% and 9.59%, respectively; and the economic budget of net ecosystem was increased by 16.15% and 12.65%, respectively (P<0.05). In summary, adding extra bentonite and biocarbon to the conventional fertilization was an effective agricultural measure for improving crop yield and reducing the global warming potential for the corn planting system in the Hetao irrigation area.