Numerical Simulation And Application Of Soil Temperature Of Tomato Under The Conditon Of Deeply Buried Straw In Greenhouse

This research set greenhouse plot experiment to analysis the variation of ground temperature in different soil layers of tomato under the conditong of deeply buried straw in greenhouse.A wireless soil moisture monitoring system was used to supervise the real-time change of soil temperature at differant deeps of 15,30 and 45cm from the platform during the growth period of tomato.The moving average method was used to adjust the seasonal data to improve the trend estimation.The time series model was established to simulate the soil temperature and to explore the effect of the different amount of straw and the soil depth to the soil temperature.The Matlab was used to fit the measured data of ground temperature at the depth of 15 cm from the surface of the ridge and the surface of the ridge,which calibrated the sine function temperature curve.The temperature curve of sinusoidal function was obtained by calculating the amplitude and fitting the phase with the conventional method.The errors between two types of fitting ground temperatures and measured ground temperature were obtained,and their fitting results were compared to select the appropriate sine function temperature curve at the deeply buried straw conditions.The soil thermal diffusivities were calculated according to amplitude and phase from the sine function temperature curve,respectively.To explore the effect of different lower limit of irrigation on soil thermal diffusivity under the deeply buried straw conditions.The main conclusions are as follows:?1?Deep straw can increase soil temperature and soil moisture content of tomato in greenhouse effectively.During the whole growth stage of tomato in greenhouse,soil temperature gradually decreased with the increase of soil depth,and the fluctuation of ground temperature gradually stabilized.When the depth of the soil layer or the amount of deep straw acts alone,it has a significant effect on the ground temperature,but when the influence of the two on the ground temperature is considered,the effect is not significant.The effect of deep burying straw on soil moisture content is most obvious at 30cm from the surface of the ridge.There was no significant difference in soil moisture content between the buried straw volume of 4.5×10⁴kg·hm^-2 and the straw-free control plot.Deep stalks have significant effects on soil moisture content.There is no significant difference in soil moisture content between different soil layers.When considering the effects of the two on soil moisture content,the effect is not significant.?2?The minimum error between measured ground temperature and simulated data was 0?at different soil depth for different straw amount.When the deep buried straw amount was 1.5×10⁴kg·hm^-2 at the depth of 15,30 and 45cm,the maximum errors were 0.52?,0.19?and 0.10?,respectively.When the deep buried straw amount was 3.0×10⁴kg·hm^-2 at the depth of 15,30 and 45cm,the maximum errors were0.65?,0.21?and 0.12?,respectively.When the deep buried straw amount was 4.5×10⁴kg·hm^-2 at the depth of 15,30 and 45cm,the maximum errors were 0.43?,0.20? and 0.09?,respectively.It was clear that the favorable simulation effects of soil temperature was obtained under the different amount of straw and the soil depth.With the increasing of the depth from platform surface under the different amount of deep buried straw,the effect of the soil temperature simulation was better and the applicability of the model was stronger.?3?The R-square of temperature curve calculated by calibration method and conventional method were both relatively high at deep soil under the condition of deeply buried straw,while the fluctuation of deep ground temperature was more stable.The soil thermal diffusivity calculated by amplitude method and phase method had a certain difference.The results indicated that the soil thermal diffusivity calculated by amplitude method was less than that by phase method under the condition of deeply buried straw.However,the relationship between the soil thermal diffusivity calculated by the two methods and the different lower limit of irrigation was the same.The soil thermal diffusivity increases with the increase of soil water content under the condition of deeply buried straw.When the soil moisture content reached a certain level,the thermal diffusivity of the soil would not increase with the water content,or even decreased with the increase of the water content.It was clear that the effect of different lower limit of irrigation on soil thermal diffusivity was nonlinear.