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Abi Saab M.T.,Lebanese Agricultural Research Institute | Todorovic M.,CIHEAM Mediterranean Agronomic Institute of Bari IAMB | Albrizio R.,CNR Institute for Agricultural and Forest Systems In the Mediterranean
Agricultural Water Management | Year: 2014

This work investigated the performance of AquaCrop and CropSyst in simulating barley growth under three water treatments (full irrigation, 50% irrigation and rainfed) and two nitrogen levels (high and low) with a particular attention to the influence of calibration year on the modelling results. Three years (2006-2008) of data from the experimental work carried out in Southern Italy were used. The models were calibrated for each of three years and then validated for two other years. The overall results pointed out that both models could be calibrated with data of one of any the three years and validated with all other data. Nevertheless, errors of estimate slightly changed in respect to the year of calibration and were sensitive, from one year to another, to weather conditions and different water and nitrogen regimes. The results indicated AquaCrop superior than CropSyst when the calibration was done on the basis of 2006 and 2008 data, whereas the models performed in a similar way when the calibration was done for 2007. In the case of final biomass, the relative RMSE was lower for AquaCrop (from 0.09 to 0.15) than for CropSyst (from 0.15 to 0.17). Similarly, in the case of final yield, the relative RMSE of AquaCrop was lower (from 0.11 to 0.17) than that of CropSyst (from 0.16 to 0.23). AquaCrop overestimated final biomass by 0.18 and 0.27 t ha-1 for 2006 and 2008 calibration year, respectively, and underestimated biomass by 1.02 t ha-1 when calibration was done on 2007 data. CropSyst underestimated biomass independently on the calibration year, from 0.83 to 1.26 t ha-1. © 2014 Elsevier B.V. All rights reserved. Source


Abi Saab M.T.,Lebanese Agricultural Research Institute | Todorovic M.,CIHEAM Mediterranean Agronomic Institute of Bari IAMB | Albrizio R.,CNR Institute for Agricultural and Forest Systems In the Mediterranean
Agricultural Water Management | Year: 2015

This work investigated the performance of AquaCrop and CropSyst in simulating barley growth under three water treatments (full irrigation, 50% irrigation and rainfed) and two nitrogen levels (high and low) with a particular attention to the influence of calibration year on the modelling results. Three years (2006-2008) of data from the experimental work carried out in Southern Italy were used. The models were calibrated for each of three years and then validated for two other years. The overall results pointed out that both models could be calibrated with data of one of any the three years and validated with all other data. Nevertheless, errors of estimate slightly changed in respect to the year of calibration and were sensitive, from one year to another, to weather conditions and different water and nitrogen regimes. The results indicated AquaCrop superior than CropSyst when the calibration was done on the basis of 2006 and 2008 data, whereas the models performed in a similar way when the calibration was done for 2007. In the case of final biomass, the relative RMSE was lower for AquaCrop (from 0.09 to 0.15) than for CropSyst (from 0.15 to 0.17). Similarly, in the case of final yield, the relative RMSE of AquaCrop was lower (from 0.11 to 0.17) than that of CropSyst (from 0.16 to 0.23). AquaCrop overestimated final biomass by 0.18 and 0.27tha-1 for 2006 and 2008 calibration year, respectively, and underestimated biomass by 1.02tha-1 when calibration was done on 2007 data. CropSyst underestimated biomass independently on the calibration year, from 0.83 to 1.26tha-1. © 2014 Elsevier B.V. Source


Levidow L.,Open University Milton Keynes | Zaccaria D.,University of California at Davis | Maia R.,University of Porto | Vivas E.,University of Porto | And 2 more authors.
Agricultural Water Management | Year: 2014

Innovative irrigation practices can enhance water efficiency, gaining an economic advantage while also reducing environmental burdens. In some cases the necessary knowledge has been provided by extension services, helping farmers to adapt and implement viable solutions, thus gaining more benefits from irrigation technology. Often investment in technological improvements has incurred higher water prices, however, without gaining the full potential benefits through water efficiency. Farmers generally lack adequate means and incentives to know crops' water use, actual irrigation applications, crops' yield response to different water management practices, and thus current on-farm water-efficiency levels.Those general difficulties are illustrated by our two case studies investigating options, stimuli and difficulties to improve water-efficient practices. The two areas have strong stimuli for improvement but lack a knowledge-exchange system to help farmers and resource managers identify scope for improvements. Partly for this reason, farmers' responsibility for efficient water management has been displaced to hypothetical prospects, e.g. extra supplies from reuse of treated wastewater or a long-term low water pricing. In both cases a displaced responsibility complements the default assumption that farmers' irrigation practices already have adequate water-use efficiency. Under current circumstances, agricultural water management will maintain the unknown water-efficiency level and farmers will have weaker incentives to make efforts for more efficient practices. A continuous knowledge-exchange is necessary so that all relevant stakeholders can share greater responsibility across the entire water-supply chain. On this basis, more water-efficient management could combine wider environmental benefits with economic advantage for farmers. © 2014 The Authors. Source

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