Simulation of N2O emissions from greenhouse vegetable production under different management systems in North China

Quantifying greenhouse gas emissions from greenhouse vegetable production systems (GVPS) is helpful to direct carbon sequestration and greenhouse gas emissions reduction. The objectives of this study were to (i) evaluate the performance of the improved WHCNS-Veg model (soil Water Heat Carbon Nitrogen Simulation for Vegetable) in simulating nitrous oxide (N₂O) emissions under different GVPS and (ii) analyze the impact of different management systems on N₂O emissions from the GVPS. Greenhouse vegetable experiments were carried out under different management systems, including conventional (CON), integrated (INT) and organic (ORG), in Quzhou County, Hebei province from 2013 to 2015. Field observations of soil water content, soil nitrate concentration and N₂O emissions were used to calibrate and validate the WHCNS-Veg model. The sensitivity analysis results showed that the effects of soil hydraulic parameters on N₂O emissions were higher than those of N transformation and vegetable genetic parameters. The improved WHCNS-Veg model simulated soil water content, soil nitrate concentration and N₂O emissions well under different GVPS. The average N₂O emissions in the spring-summer season (16.3 kg N ha⁻¹) were about 2.5 times higher than the autumn-winter season (6.4 kg N ha⁻¹). Among the four seasons, the average N₂O emissions of CON, ORG and INT were 13.5, 11.3 and 9.3 kg N ha⁻¹, respectively, accounting for 1.4–1.7% of the total fertilizer input. The N₂O emissions of the INT and ORG systems were 31.1% and 16.3% lower than the CON treatment, respectively. The results indicated that the improved WHCNS-Veg model can be used to simulate and analyze N₂O emissions under different management systems and substituting organic manure for chemical fertilizer could effectively reduce the N₂O emissions in the GVPS.