Simulation of the soil water balance of wheat using daily weather forecast messages to estimate the reference evapotranspiration

Abstract

Abstract. Aiming at developing real time water balance modelling for irrigation scheduling, this study assesses the accuracy of using the reference evapotranspiration (ET o ) estimated from daily weather forecast messages (ET o,WF ) as model input. A previous study applied to eight locations in China (Cai et al., 2007) has shown the feasibility for estimating ET o,WF with the FAO Penman-Monteith equation using daily forecasts of maximum and minimum temperature, cloudiness and wind speed. In this study, the global radiation is estimated from the difference between the forecasted maximum and minimum temperatures, the actual vapour pressure is estimated from the forecasted minimum temperature and the wind speed is obtained from converting the common wind scales into wind speed. The present application refers to a location in the North China Plain, Daxing, for the wheat crop seasons of 2005-2006 and 2006-2007. Results comparing ET o,WF with ET o computed with observed data (ET o,obs ) have shown favourable goodness of fitting indicators and a RMSE of 0.77 mm d −1 . ET o was underestimated in the first year and overestimated in the second. The water balance model ISAREG was calibrated with data from four treatments for the first season and validated with data of five treatments in the second season using observed weather data. The calibrated crop parameters were used in the simulations of the same treatments using ET o,WF as model input. Errors in predicting the soil water content are small, 0.010 and 0.012 m 3 m −3 , respectively for the first and second year. Other indicators also confirm the goodness of model predictions. It could be concluded that using ET o computed from daily weather forecast messages provides for accurate model predictions and to use an irrigation scheduling model in real time.

Simulation of evapotranspiration and carbon dioxide flux in the wheat‐maize rotation croplands of the North China Plain using the Simple Biosphere Model

“…Therefore, the accurate modelling of regional ET and carbon dioxide flux for this plain is important in understanding water and carbon budgets and in assessing the effects of climate change or crop management on water resources and food production. Up to now, there have been several field experiments implemented in this region (Qiu et al , 2008; Tong et al , 2009; Cai et al , 2009; Lei and Yang, 2010). The overall goal of these experiments is to understand the water and carbon dioxide exchange for wheat and maize.…”

Rendimento De Grãos De Milho Irrigado Por Gotejamento Subterrâneo E Estimativa Da Irrigação Com Dados Da Previsão Do Tempo

“…Estes autores, estimaram a ETo (FAO -PM) no período compreendido entre 1996 e 2012, para um a nove dias de antecedência ao dia observado para Shepparton na Austrália e obtiveram valores de RMSE variando entre 0,65 e 1,26 mm dia -1 . Resultado semelhante foi obtido por Cai et al (2009), em estudo conduzido na China, durante dois anos agrícolas para a cultura do trigo, que obtiveram um RMSE de 0,77 mm dia -1 .…”

“…Nestes casos, a utilização de dados da previsão do tempo, que são amplamente disponíveis por diferentes portais de meteorologia e diferentes meios de comunicação, podem ser uma alternativa para estimativa da ETo (XU et al, 2012;SILVA et al, 2010;ER-RAKI et al, 2010;ISHAK et al, 2010;CAI et al, 2007;CAI et al, 2009;PERERA et al, 2013), e a partir desta, a realização da recomendação da necessidade de irrigação, seguindo a metodologia proposta por Allen et al (1998 O delineamento experimental utilizado foi o inteiramente casualizado, no esquema fatorial 2 x 2, com três repetições, sendo o fator "A" duas profundidades de instalação do tubogotejador: (i) 20 cm e (ii) 40 cm. O fator "D" contou de dois espaçamentos entrelinhas dos tubogotejadores: (i) 90 cm e (ii) 135 cm.…”

Seasonal Variations in Water Uptake Patterns of Winter Wheat under Different Irrigation and Fertilization Treatments

“…elevation) (Figure 1a). The climate in this area is subhumid with a mean annual precipitation of 540 mm and a mean annual temperature of 12.1 °C [26]. However, precipitation during the winter wheat season only accounts for 20 to 30% of the annual precipitation, which is far less than the mean seasonal reference evapotranspiration (ET0) (610 mm).…”