Study On The Characteristics Of Water And Heat Fluxes Of Farmland And Orchard In The Low Hilly Region Of Red Soil

The growth of crops depends on the field microclimate environment, and microclimate characteristics of farmland is determined by the exchange of material and energy in the gas system. Studying on microclimate law, water and heat flux characteristics of farmlands and orchards in hilly red soil area has scientific significance for depth understanding water and heat balance characteristics and ecological functions, has practical significance for making full use of climate resources, ensuring normal growth of crops and regulating water resources. This paper makes use of the combination of Bowen-ratio energy, automatic meteorological station and soil temperature and humidity sensor, measures farmland microclimate elements to establish a farmland actual evapotranspiration formula to analysis mcroclimate characteristics of farmland and orchards, water and heat flux component and the law of plants evapotranspiration. This experiment has been done in Yingtan Sunjia small watershed. The climate in this area has a representative. The results can provide a reference for the development of water-saving agriculture in southern China red soil hilly region. The primary conclusions are as follows:(1)The soil moisture of orangery and peanut had significant seasonal variations during the test. Although the trends were consistent, different depths had different magnitudes. In addition to precipitation, the soil moisture were affected by temperature, relative humidity, solar radiation and other factors at the time of no precipitation.With the deepening of soil depth, the seasonal trends of soil temperature were more gentle. In one day, different soil layers had different change ranges and different times of extreme, the time of extremum occurrence in the orangery was half an hour later than the time of extremum occurrence in the peanut. The temperature, solar radiation and relative humidity were the environmental factors affecting soil temperature, among them the solar radiation was the greatest impact on peanut soil temperature. Soil surface was most vulnerable to temperature, solar radiation and relative humidity.(2)Diurnal variation of energy balance components of orangery and peanut both appeared unimodal curves, and the peak occurred at midday. Each component were sensitive to weather conditions, exhibited different variations under different weather conditions. By comparing energy balance characteristics of two different underlying surface we found:the net radiation of peanut was lower than that of peanut, the sensible heat flux of peanut was more sensitive to weather condition than the orangery, the soil heat flux was on the contrary.(3)The distribution of soil heat flux had obvious seasonal pattern, the soil storaged heat in March5,6,7and discharged heat in August and September. The latent heat flux occupied the main part of energy, and the minimum occurred in May. The latent heat flux distribution of energy increased starting in June and declined in August and September.(4)In this paper, daily ET estimation models about orangery and peanut were established according to the measured data and theoretical knowledge. Verifications of the models showed that the relative errors were within an acceptable range, in addition to individual higher than10%, the rest were less than10%, the mode applicabilities were possible.