仪器测墒按需补灌对冬小麦产量和水分利用效率的影响

摘要

In this experiment ,the field capacity ( FCv ) and soil volumetric moisture content (WCv ) were measured by three kinds of soil moisture instruments as frequency domain reflection (FDR) ,time domain reflection (TDR) and standing wave ratio (SWR ) under field condition .The target relative soil moisture content was controlled as 80% ,70%and 70% in before the winter ,jointing stage and anthesis stage ,respectively .The soil depths for measuring soil moisture were set 20 ,40 cm and 60 cm in each supplemental irrigation stage .The accuracy and stability of different instruments for soil moisture measuring during growing season of winter wheat has been researched to explore the effect and different reasons measuring soil moisture by different instruments to calculate irrigation quota for supplemental irrigation .The re-sults showed that :The relative error was 0 .4% ~2 .6% comparing the FCv - m measured by FDR and SWR with the FCm measured by the traditional method .The relative error between the WCv - m measured by TDR and the WCm mea-sured by drying method has shown a significant positive correlation with the related soil depth temperature .It was high in sowing period ,blossom stage and mature period ,but was lower in before wintering and jointing stage .The relative error of WCv - m and WCm measured by SWR with the soil moisture content was a significant negative correlation ,the measured accuracy was higher under the condition of higher soil moisture content .The measured accuracy and stability of FDR were total higher ,which less affected by soil temperature and soil moisture in the growing season of winter wheat .Direct using the FCv and WCv measured by FDR to calculate the irrigation quota for supplemental irrigation have obtained the coinci-dence effect with the traditional drying method .%利用频域反射法（FDR ）、时域反射法（TDR ）和驻波率法（SWR ）三种便携式土壤水分快速测试仪，在田间条件下测定土壤田间持水量（FCv）和体积含水量（WCv），于冬小麦越冬前、拔节期和开花期设补灌的目标土壤相对含水量分别为80％、70％和70％，每一补灌时期设20 cm、40 cm和60 cm三个测墒土层深度，研究不同仪器法在冬小麦生育期间对土壤水分测定的准确度和稳定性，探索用不同仪器测定数据计算灌水定额进行冬小麦补灌的效果及其差异原因。结果表明，FDR和SWR仪器测得的 FCv 换算为以水土质量百分比表示的田间持水量FCv － m ，与传统方法测得的田间持水量 FCm之间的相对误差为0．4％～2．6％；TDR仪器测定计算得出的 WCv － m值与烘干法测得的WCm值的相对误差与相应土层土壤温度呈极显著正相关，在冬小麦播种期、开花期和成熟期较高，在越冬前和拔节期较低；SWR仪器测定计算得出的 WCv － m值与WCm值的相对误差与相应土层土壤含水量呈极显著负相关，在土壤含水量较高的条件下测量的准确度较高。FDR仪器在冬小麦生育期内测量的准确性受土壤温度和水分的影响较小，准确度和稳定性均较高，直接利用其测定的 FCv和WCv值计算灌水定额补灌，获得了与传统烘干法测墒补灌一致的效果。