Yield and gas exchange of greenhouse tomato at different nitrogen levels under aerated irrigation.

Significant global warming increases over the last century have resulted in recent research focused on practices to reduce greenhouse gas (GHG) emissions. Agricultural management practices, such as nitrogen (N) fertilization and aerated irrigation (AI), have significantly increased crop yields by improving soil water and fertilizer availability, and have been widely adopted in recent years. However, the interactive impact of different growing seasons and management practices in the greenhouse on GHG emissions is unclear. This greenhouse study was conducted during Spring and Autumn cultivation periods in Yangling, China with five N application rates (0, 50, 150, 200,250 kg ha-1) and two irrigation methods (AI and conventional irrigation [CK]). The results indicated that AI and N application both increased tomato yield, but also increased soil CO2 and N2O emissions. The temperature was 4 °C higher during Spring cultivation than during Autumn cultivation, which significantly (P < 0.05) increased soil emissions of CO2, N2O, and net GHG by 10.6%, 43.8%, and 12.3%, respectively. However, the yield in Spring cultivation only increased by 5.1% (P > 0.05). Thus, among the selectable cultivation seasons, the cooler season (Autumn) along with AI and 200 kg N ha-1, was recommended to farmers to avoid adverse effects of a warming environment. AI and 150 kg N ha-1 in Spring cultivation could be recommended as an alternative measure to local farmers. Our results suggest that in a future warmer climate, reducing nitrogen fertilizer rate in conjunction with the use of AI will remain important practices for maintaining crop yield while reducing soil net GHG emissions. There is an urgent need to transform current management practices to offset the negative impacts of climate change.

[Effects of aerated irrigation on CO2 and N2O emission from protected melon soils under different nitrogen application levels]. / åŠ æ°”çŒæº‰å¯¹ä¸åŒæ–½æ°®æ°´å¹³çš„è®¾æ–½ç”œç“œåœŸå£¤CO2和N2O排放的影响.

To reveal the effects of coupling nitrogen (N) application and aerated irrigation on soil CO2 and N2O emission, and their relationship with soil temperature and moisture, an experiment was conducted in greenhouse melon fields by using the method of static chamber/gas chromatography to determine the CO2 and N2O emissions of different nitrogen rates under aerated irrigation. There were two irrigation factors (AI: aerated irrigation; CK: conventional irrigation) and three N levels (N1: 0; N2: 150 kg·hm-2, the traditional nitrogen application rate was 2/3; N3: 225 kg·hm-2, traditional nitrogen application rate). The results showed that soil CO2 and N2O emissions in AI treatment were higher than those in CK, but no significant difference was observed between the two irrigation methods. Under the same irrigation method, soil CO2 and N2O emission significantly increased with the increases of N application rate, indicating that N application was the main influencing factor for CO2 and N2O emissions. There were significant positive relationships between soil N2O emissions and soil temperature and water filled pore space (WFPS) under the AI treatment. Soil CO2 emission were positively correlated with soil temperature. When N application reduced to N2 rate under AI treatment, the yield was increased by 6.9% and the greenhouse warming potential was reduced from 9544.82 kg·hm-2 to 9340.72 kg·hm-2. Thus, it is feasible to reduce the amount of N fertilizer under AI treatment to mitigate greenhouse gas emission in agricultural production systems.