利用电容式传感器连续监测土壤硝态氮质量分数的试验研究

Use of Capacitance Sensors for Continuous Monitoring of Nitrate Content in Soil

通过室内和田间试验,研究土壤硝态氮质量分数与电容式传感器监测的土壤电导率、含水率和温度的定量关系。在室内以NH4NO3分析纯为溶质,进行了溶液质量浓度0～10g/L的7次土柱试验;在2009年和2010年春玉米生育期内监测了不同滴灌水量条件下土壤电导率、含水率和温度动态变化。结果表明,土壤电导率能较好的反映土壤硝态氮质量分数的变化;土壤硝态氮质量分数与电导率、含水率和温度之间的关系可用二次多项式描述,且3个土壤参数对土壤硝态氮质量分数的影响均达到了极显著水平(P≤0.01);由于回归模型的拟合精度受土壤初始养分盐分质量分数及空间变异等因素的影响,为获得较高的预测精度,应进行田间标定。

Continuous monitoring of nitrate in soil is needed to optimize nutrient management and reduce nitrate leaching.Both laboratory and field calibration experiments were conducted to quantify the relationship between nitrate content in soil and soil bulk electrical conductivity,water content and temperature monitored by capacitance sensors.In laboratory experiment,seven soil container tests were conducted with varying injection concentrations of ammonium nitrate ranging from 0 to 10 g/L.Also Soil bulk electrical conductivity,water content,and temperature were continuously monitored during the growing seasons of spring corn drip irrigated at different levels in 2009 and 2010.The results showed that the bulk electrical conductivity could reflect the dynamics of nitrate content in soil.The relationship between soil nitrate content and soil bulk electrical conductivity,water content and temperature could be described by a quadratic polynomial.All of the three parameters monitored by the capacitance sensors had significant effects on nitrate content in soil（P≤0.01）.In situ calibration was recommenced by this study to improve the prediction accuracy of nitrate content in soil as the accuracy of the regression polynomial was influenced by many factors,such as initial soil nutrients,salt contents and spatial variability.