The coordinated use of surface- and ground-water over time and space as two components of a single irrigation system is of outmost importance in many rural areas of the world, in order to assure crop production sustainability, to restore ongoing and to prevent future issues related to freshwater quality and quantity mismanagement/deterioration. New technological solutions, such as GIS-integrated simulation models, may provide reliable tools in order to evaluate impacts in space and time and to properly manage conjunctive use of surface water and groundwater and water-constrained agricultural production. After presenting the common open source simulation programs for dealing with conjunctive use, we discuss and present the integration of the Farm Process (FMP; embedded in the USGS's MODFLOW One-Water Hydrologic Model) coupled to a Crop Growth Module (CGM) within the open source and public domain QGIS-integrated FREEWAT platform. Using FMP in FREEWAT gains the benefit of the spatial environment and data management tools of a GIS solution, and to perform proper analysis of dynamically integrated terms of the hydrological cycle, to effectively balance crop water demand and supply from different sources of water. A simple hypothetic, yet realistic, application of the proposed approach with FMP and CGM is presented, simulating the yield of irrigated sunflower at harvest in a Mediterranean area. Results provide an insight on the potential exploitation of the developed solution, including, but not limited, to: quantitative temporal analysis of irrigation water sources, detailed analysis of evaporation and transpiration terms (from irrigation, groundwater or rainfall). The coupling of FMP with CGM to estimate crop yield at harvest provides further management tools when dealing with crop productivity. In the simulated case study, the analysis of the water balance terms allowed identifying the relevance of the groundwater contribution to ETc-act, highlighting the role of natural root uptake. The proposed solution is thought to be deployed by water authorities, large farms and public/private companies managing irrigation areas. The use of these tools calls for dedicated capacity building to boost digitalization in the agricultural water sector in order to achieve data-based agricultural water management.
Abstract Giant reed ( Arundo donax L.) and miscanthus ( Miscanthus × giganteus Greef et Deu.) are two perennial rhizomatous grasses ( PRG s), considered as promising sources of lignocellulosic biomass for renewable energy production. Although the agronomic performance of these species has been addressed by several studies, the literature dedicated to the crop water use of giant reed and miscanthus is still limited. Our objective was thus to investigate giant reed and miscanthus water use by assessing crop evapotranspiration ( ET c ), crop coefficients (K c ) and water use efficiency ( WUE ). The study was carried out in central Italy and specifically designed water‐balance lysimeters were used to investigate the water use of these PRG s during the 2010 and 2011 growing seasons. Giant reed showed the highest cumulative evapotranspiration, with an average consumption of approximately 1100 mm, nearly 20% higher than miscanthus (900 mm). Crop evapotranspiration rates differed significantly between the species, particularly during the midseason (from June to September), when average daily ET c was 7.4 and 6.2 mm in giant reed and miscanthus respectively. The K c values determined in our study varied from 0.4 to 1.9 for giant reed and 0.3 to 1.6 for miscanthus. Finally, WUE was higher in miscanthus than in giant reed, with average values of 4.2 and 3.1 g L −1 respectively. Further studies concerning water use under nonoptimal water conditions should be carried out and an assessment of the response to water stress of both crops is necessary to integrate the findings from this study.
Introducing nitrogen N2-fixing crops into cereal-based crop rotations reduces N-fertiliser use and may mitigate soil emissions of nitrous oxide (N2O). However, the effect of the cultivation of N2-fixing crops on N2O emissions is still not well understood. N2O from N2-fixing crops can be emitted in two ways: during biological N2 fixation itself and when legume residues are returned to the soil. A field trial was carried out on clover (Trifolium squarrosum Savi) to test the role of leguminous crops on N2O emissions in the Mediterranean environment. Monitoring was performed from December 2013 to September 2014. Cumulated N-N2O fluxes were calculated for the growing season (Phase 1) and the post-harvest period (Phase 2) in order to assess the importance of each phase. Our results did not show statistically significant differences between the two phases in term of contribution to the total cumulative N-N2O emissions, in fact Phase 1 and Phase 2 accounted respectively for 43 and 57% of the total.
The effect of two row spacing configurations and four water supply levels was investigated on sweet and fibre sorghum in Central Italy for two consecutive years. Results highlighted the influence of both irrigation and row spatial configuration on crop productivity. Indeed, several studies have pointed out the positive response of sorghum to irrigation in Mediterranean climate, as in this environment water stress represents one of the main limiting factors on crop productivity. On the other hand, few attempts have been made to explore the role of row spacing on energy sorghum productivity. Results outlined an average increase in sorghum dry biomass yield ranging from +23% to +79% at variable rates of water supply as compared to rainfed control. The positive effect of irrigation was also observed on leaf area index and radiation use efficiency. Moreover, we observed a crop yield increase, from 9% to 20%, under double row spacing compared to the standard planting pattern (i.e. single row spacing). Finally, it was confirmed the efficient use of water by sorghum and the great ability of sorghum to increase its biomass yield in response to increasing volumes of water supplied. Therefore, this work suggests how row spacing configuration and drip irrigation could be feasible technical options to increase sorghum biomass yields in Mediterranean environments. These techniques should be experienced by farmers towards a sustainable intensification of current cropping systems.
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