中子仪测定砂性土壤水分的标定与测试参数的界定分析  

Calibration of Neutron Probe Measuring Sandy Soil Moisture and Analysis of Defining the Test Parameters

作　　者：刘巧玲[1] 刘小燕[1] 刘廷玺[1] 段利民[1] 岳翠桐 

机构地区：[1]内蒙古农业大学水利与土木建筑工程学院,呼和浩特010018

出　　处：《中国农业气象》2015年第2期178-186,共9页Chinese Journal of Agrometeorology

基　　金：国家自然科学基金地区和重点资助项目(51169012;51139002;51369016);教育部创新团队发展计划(IRT13069);内蒙古自治区草原英才产业创新创业人才团队;内蒙古农业大学寒旱区水资源利用创新团队项目(NDTD2010-6)

摘　　要：以科尔沁沙地6个砂性土壤试验点为研究对象,实施中子水分仪测试土壤水分的标定试验,采用点聚图筛选和三点平滑处理土壤体积含水率数据,选用线性标定和非线性标定2种形式,系统分析中子仪计数时间、中子管安装稳定时间以及降雨、灌水等提高土壤含水率的方法对标定结果的影响,以界定中子仪的测试参数,经模拟与验证,确定砂性土壤的中子仪标定方程。结果表明:砂性土壤0-30cm表土采用二项式标定效果相对较好;砂土土质对中子仪读数影响较小,两种不同含水率的土壤可以统一标定;中子管安装稳定时间至少需7d,尤以经历一、两场较大降雨后进行标定其试验误差较小;标定和测量实施过程中,中子仪计数时间宜选用64s,再适当加大计数时间也能得到较好结果;在较大降雨和干旱两种状态下,选用64s中子仪计数时间进行测量,可得到砂性土壤测量水分范围为1.01%~29.92%且精度较高的标定方程。验证结果表明,中子仪测量结果能反映实际土壤含水量的分布状况,标定方程精度可满足实际测试要求。Six sandy soil sites of Horqin Sandy Land were selected for neutron probe calibration,which was used for measuring soil moisture.Scatter diagram screening and three-dot smoothing methods were used for processing soil volumetric moisture data.In order to define the testing parameters,linear and non-linear calibration models were applied to analyze systematically the calibrated results,which influenced by neutron probe counting time,installation stable time,rainfall and irrigation.The calibrated equation of sandy soils was established through simulation and verification.The results showed that polynomial calibration was more suitable for top sandy soil(0 to 30cm).Soil with different moisture could be unified calibration because of sandy soil had little effect on the neutron probe readings.The neutron probe could installed stably at least after 7 days,and the errors would be small especially calibrating after one or two heavy rainfalls.64 seconds of counting time was better when calibrating and measuring.The results would be better if the counting time increased.Under the heavy rain and drought situation,by choosing 64 seconds counting times,high precision calibrated equations could be got with soil moisture within 1.01% to 29.92%.The results indicated that the neutron probe method could be used to test soil moisture,and the calibrated equations precision could be satisfied the actual test requirements.

关 键 词：中子计数比 土壤含水量 三点平滑处理 平均相对误差 

分 类 号：S152.7[农业科学—土壤学]