Modeling the amount of greenhouse gas emissions of gardens in Khuzestan province

The main causes of global climate change and biodiversity is emission of greenhouse gases from various sources especially from agricultural sector. As one of agricultural hubs Khuzestan has major share in production greenhouse gases with high consumption of chemical fertilizers. Purpose of research present study is applied analytical study that used DAYCENT and DNDC models to determine growth rate of methane, oxidant nitrous and oxidantritic gases in citrus and palm groves of Khuzestan. For this purpose, area was divided into three sections and in each section sampling and determination gas concentration in gardens in each section was performed randomly. Sampling time was done in flowering stage in May 2020 which was peak of green cover for tree, concentration of exhaust gas was done using closed chamber method and gas chromatography in sampling sites. Global warming potential was also obtained based on observational data and DAYCENT and DNDC models. Then efficiency of DAYCENT and DNDC models was investigated using coefficients of determination coefficient, maximum error, root of mean error squares, model efficiency and residual mass coefficient. According to results of DAYCENT model was determined, highest average methane flux modeled in Dezful (ton/hectare in 0.448) and nitrous oxide flux modeled at Abadan (0.014 ton/ha per year) and oxidized nitric flux modeled at Dezful (ton/hectare in 0.152). Also, in DNDC model, highest average of methane flux modeled at Dezful (ton/hectare in 0.374) oxidized nitrous flux modeled at Abadan (ton/hectare at 0.258) and oxidative flux modeled at Dezful (A ton per hectare was obtained in 0.118. Highest global warming potential was determined based on observational data at Abadan (1339.95 tons equivalent to carbon dioxide) and based on DAYCENT data at Dezful (58.114 tons equivalent to carbon dioxide) and based on DNDC data at Abadan (111.669 tons equivalent to carbon dioxide). According to results statistical indicators of DAYCENT model for three gases of oxidenitros, methane and oxidantitric respectively, coefficient of determination (0.98,0.99 and 0.77) root of mean error squares (0.05,0.31 and 0.03) and efficiency of model (0.61,0.85 and 0.76) and in DNDC model coefficients of determination coefficient (0.98,0.98 and 0.8) root of mean error squares (0.01,0.45 and 0.04) and efficiency of model (0.95, 0.68 and 0.63) and both models showed acceptable accuracy in estimating said greenhouse gases.It is recommended that instead over-consumption of chemical fertilizers as a major source of greenhouse gas emissions, opinions experts and principles optimal use of fertilizers on farm be used