采用作物系数法和PM模型估算南京地区玉米田蒸发蒸腾量

蒸发蒸腾量(ET)是农田水平衡中的重要环节,ET的准确估算有助于提高农田水分管理水平。在测定农田小气候、土壤蒸发和玉米生长旺季液流量基础上,比较了单作物系数法(Kc法)、双作物系数法(Kcb法)、不同冠层阻力计算的Penman-Monteith模型(PM1和PM2法)估算南京地区玉米田ET的适用性,并对玉米整个生育期ET变化及其影响因素进行分析。结果表明以液流法和土壤蒸发测定的总ET为基准,PM1方法估算的夏玉米ET误差最小,与实际测定ET的决定系数(R2)、平均绝对误差(MAE)和一致性指数(d)分别为0.52、0.8 mm/d和0.48。以PM1模型估算的夏玉米全生育期ET为310mm,日均ET为3.16mm/d,最大值出现在拔节期和抽穗期,整体变化呈单峰型。ET与气象因素响应顺序为净辐射饱和水汽压温度风速。本研究可为优化玉米田水资源管理和提高水资源有效利用提供参考。

Evaluation of Evapotranspiration of Maize With Crop Coefficient and Penman-Monteith Methods in Nanj ing

Maize is an important food crop in Nanjing.In order to improve the water management and increase the yield,it is crucial to investigate the precise water consumption for maize and its influencing factors.Evapotranspiration (ET)was observed using sap flow and soil evaporation method during fully developed canopy period,and micro-meteorology factors were also measured by auto-matic weather station during 2015.We analyze the seasonal variation of maize ET and simulate ET using Penman-Monteith (PM1 and PM2)and crop coefficient (single and duo)method in Nanjing University of Information Science & Technology experiment site for agricultural meteorology (118.8°E,32.0°N,with altitude 32 m).The results showed that the PM1 method performs best among the four methods,with determine coefficient (R2 )0.52,mean absolute error 0.8 mm/d,and index of agreement 0.48,respectively. ET increased gradually to 7 mm/d in the s shooting stage,and decreased after the canopy was well developed.The PM1 method cal-culating ET was 310 mm for the whole season and the daily mean ET was 3.16 mm/d.ET was mainly controlled by net radiation (Rn),vapor pressure deficit (D),and air temperature (T)and the order of determination coefficient for environmental factors was Rn>D>T.It was concluded that using PM1 method could evaluate the ET during the whole season and the results could optimize the water management of maize field and improve the water resources using efficiency in Nanj ing.