黄土塬区农田土壤温度变化特征研究

Study on Characteristics of Soil Temperature Changes in Arable Land on the Loess Tableland

根据长武农业生态试验站深剖面土壤水热观测场2011年的观测资料,分析了农田土壤温度日变化、季节变化特征及其与休闲地土壤温度的差异。结果表明:农田0—20cm(冬季0—10cm)土层土壤温度呈正弦曲线趋势变化;垂直剖面上,土层越深,土壤温度的日振幅越小;土壤日最高和最低温度出现的时间越晚。土壤温度的日振幅,春季最大,夏秋次之,冬季最小;土壤日最高和最低温度出现的时间春、夏季较早,秋季次之,冬季较晚。典型晴天的土壤温度的日变化曲线较典型阴天的平滑且土壤温度的日振幅较大。就季节变化而言,农田与休闲地土壤温度的季节变化趋势一致,但是农田0—70cm土层的月平均最高温度出现的时间较休闲地有所滞后;农田0—110cm间各土层的月平均最高温度低于休闲地0.6～1.5℃,月平均最低温度低于休闲地0.2～1.1℃。7—8月农田土壤日平均温度显著低于休闲地,而降雨会明显降低农田与休闲地的土壤温度差异。

The variation characteristics of soil temperature in 2011 were analyzed in an arable land, based on the soil temperature data measured at the soil moisture-heat monitoring field at the Changwu agro-ecological experimental station on the Loess Plateau of China. The results show that soil temperature at the depth of 0--20 cm displayed an obvious daily variation in arable land while it can be expressed as a sine curve at the depth of 0--10 cm in winter. The soil temperature amplitude decreased gradually and the phase variation of soil temperature displayed a gradual lag with the increase of soil depth. The soil temperature amplitude is the maximum in spring, the middle in summer and autumn, the minimum in winter. The curve for soil tempera- ture of sunny day is smoother and the soil temperature amplitude is bigger than cloudy day. Additionally, a similar seasonal variation of soil temperature was observed in arable land and bare land, but the time that the highest monthly mean of soil temperature occurred between 0 and 70 cm in arable land was lagged compared with bare land. The highest monthly mean of soil temperature at the depth between 0 and 110 cm varied from 0.6 ℃ to 1.5 ℃ which was lower than that in the bare land, and the lowest monthly mean of soil temperature was from 0.2℃ to 1. 1℃ lower than that in the bare land. The daily mean of soil temperature in arable land is obviously lower than that in bare land, and the difference value decreased significantly when a rainfall occurred.