[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.