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DOI:10.13522/j.cnki.ggps.2022657 |
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Effects of Different Tillage and Nitrogen Applications on N2O Emission and Mineral Nitrogen in Surface Water of Paddy Field |
WU Qingfeng, ZHENG Jiashun, XIAO Wei, LI Fusheng
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College of Agriculture, Guangxi University, Nanning 530004, China
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Abstract: |
【Objective】Rice in southern China is traditionally grown in paddy fields and improving its fertilizer use efficiency and reducing greenhouse emissions is critical to helping achieve the mandatory goal of zero-increase in agrochemical application without compromising crop yield. This paper presents the findings of an experimental study on combined effect of tillage and nitrogen application on N2O emission and mineral N concentrations in surface water of the paddy fields.【Method】The experiment was conducted in a double-cropping rice field and involved four tillage treatments: zero tillage (T), micro tillage (C), rotary tillage (R), and smash ridging tillage (S). For each tillage treatment, there were two N fertilizations: conventional N application at 1 225 kg/hm2 (N1) and reducing N application to 150 kg/hm2 (N2). N2O emission and mineral N concentration in the surface water in each treatment were measured 1, 3, and 5 days after N fertilization at different growth stages of the rice.【Result】① One day after N fertilization, ammonium concentration in the surface water increased rapidly to a peak one and then declined quickly. In the conventional fertilization (N1) where N was applied at both tillering and booting stage, zero-tillage increased ammonium concentration in the surface water by 4.7%~532.6%, compared to other treatments. Overall, nitrate and nitrite concentrations in the surface water of all treatments were in the range 0.08~0.20 μg/mL and less than 0.12 μg/mL, respectively. ② Reducing N application and applying it as basal fertilization and topdressing at tillering and booting stages, TN2 reduced N2O emission more than other tillage treatments. ③ N2O emission was negatively correlated to ammonium concentration in the surface water 1~5 days after N fertilization, with the correlation coefficient varying from -0.300~-0.509, depending on the timing of the fertilization. 【Conclusion】After N fertilization, ammonium became the primary inorganic nitrogen in the surface water. Ammonium concentration of the surface water 1~5 days after the fertilization impacted N2O emissions, irrespective of the timing of the fertilization. |
Key words: tillage method; nitrogen rate; inorganic nitrogen; N2O emission; paddy soil |
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