Coping with Water Scarcity: What Role for Biotechnologies?

At a conference of the FAO Biotechnology Forum in 2007, 78 participants from 24 countries offered their views on agricultural biotechnologies and water scarcity, addressing the pros and cons of various methods and their potential application. These viewpoints are represented in this discussion paper, along with an introductory section that defines the issues to be discussed. Funders in the WASH sector can use this document to educate themselves about the potential gains to be made in supporting different types of scientific research and agricultural technology development

AquaCrop Version 7.0 - New Developments

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Sustainable intensification of agriculture for human prosperity and global sustainability

There is an ongoing debate on what constitutes sustainable intensification of agriculture (SIA). In this paper, we propose that a paradigm for sustainable intensification can be defined and translated into an operational framework for agricultural development. We argue that this paradigm must now be defined-at all scales-in the context of rapidly rising global environmental changes in the Anthropocene, while focusing on eradicating poverty and hunger and contributing to human wellbeing. The criteria and approach we propose, for a paradigm shift towards sustainable intensification of agriculture, integrates the dual and interdependent goals of using sustainable practices to meet rising human needs while contributing to resilience and sustainability of landscapes, the biosphere, and the Earth system. Both of these, in turn, are required to sustain the future viability of agriculture. This paradigm shift aims at repositioning world agriculture from its current role as the world's single largest driver of global environmental change, to becoming a key contributor of a global transition to a sustainable world within a safe operating space on Earth

Optimizing drip irrigation for eggplant crops in semi-arid zones using evolving thresholds

AbstractField experiments were combined with a numerical model to optimize drip irrigation management based on soil matric potential (SMP) measurements. An experimental crop of eggplant was grown in Burkina Faso from December 2014 to March 2015 and plant response to water stress was investigated by applying four different irrigation treatments. Treatments consisted in using two different irrigation depths (low or high), combined with a water provision of 150%, 100% or 66% (150/100/66) of the maximum crop evapotranspiration (T150low, T66low, T100high, T66high). Soil matric potential measurements at 5, 10 and 15cm depth were taken using a wireless sensor network and were compared with measurements of plant and root biomass and crop yields. Field data were used to calibrate a numerical model to simulate triggered drip irrigation. Different simulations were built using the software HYDRUS 2D/3D to analyze the impact of the irrigation depth and frequency, the irrigation threshold and the soil texture on plant transpiration and water losses. Numerical results highlighted the great impact of the root distribution on the soil water dynamics and the importance of the sensor location to define thresholds. A fixed optimal sensor depth of 10 cm was found to manage irrigation from the vegetative state to the end of fruit development. Thresholds were defined to minimize water losses while allowing a sufficient soil water availability for optimal crop production. A threshold at 10cm depth of −15kPa is recommended for the early growth stage and −40kPa during the fruit formation and maturation phase. Simulations showed that those thresholds resulted in optimal transpiration regardless of the soil texture so that this management system can constitute the basis of an irrigation schedule for eggplant crops and possibly other vegetable crops in semi-arid regions

Şeker sorgumunun fotosentetik su kullanım randımanının bitki örtü ve yaprak düzeylerinde karşılaştırılması

Little is known about the response of sweet sorghum to water stress. Therefore, the aim of this study was to characterize sweet sorghum physiological water use efficiency (WUE) under progressing water stress conditions, with emphasis on the canopy scale as compared with the leaf scale. Sweet sorghum ( Sorghum bicolor(L.) Moench) was subjected to two water stress cycles. Energy, water vapor, and $CO_2$ fluxes were estimated at the canopy scale by means of the Bowen ratio/energy balance/CO 2 gradient method (BREB+), and at the leaf scale with a portable photosynthesis system. Predawn ($\psi$b) and noon-time leaf water potential (yn) were measured by pressure chamber. Canopy and leaf photosynthetic WUE showed parallel behavior. They decreased following an increase in leaf-to-air vapor pressure deficit (VPD) and a decrease in yb. The variation in soil-water status, estimated by yb, ranged from -0.2 to -1.1 MPa and in VPD from 2.3 to 5.8 kPa at the leaf scale, and from 1.4 to 5.5 kPa at the canopy scale, during the experimental period. Mean values of noon-time photosynthetic WUE were around 5 and 4.3 $mmol_{CO_2}$ .$mol^{ -1}_ {H_2O}$ for leaf and canopy scales, respectively.Little is known about the response of sweet sorghum to water stress. Therefore, the aim of this study was to characterize sweet sorghum physiological water use efficiency (WUE) under progressing water stress conditions, with emphasis on the canopy scale as compared with the leaf scale. Sweet sorghum ( Sorghum bicolor(L.) Moench) was subjected to two water stress cycles. Energy, water vapor, and $CO_2$ fluxes were estimated at the canopy scale by means of the Bowen ratio/energy balance/CO 2 gradient method (BREB+), and at the leaf scale with a portable photosynthesis system. Predawn ($\psi$b) and noon-time leaf water potential (yn) were measured by pressure chamber. Canopy and leaf photosynthetic WUE showed parallel behavior. They decreased following an increase in leaf-to-air vapor pressure deficit (VPD) and a decrease in yb. The variation in soil-water status, estimated by yb, ranged from -0.2 to -1.1 MPa and in VPD from 2.3 to 5.8 kPa at the leaf scale, and from 1.4 to 5.5 kPa at the canopy scale, during the experimental period. Mean values of noon-time photosynthetic WUE were around 5 and 4.3 $mmol_{CO_2}$ .$mol^{ -1}_ {H_2O}$ for leaf and canopy scales, respectively

Prediction of Climatic Change for the Next 100 Years in the Apulia Region, Southern Italy

The impact of climate change on water resources and use for agricultural production has become a critical question for sustainability. Our objective was investigate the impact of the expected climate changes for the next 100 years on the water balance variations, climatic classifications, and crop water requirements in the Apulia region (Southern Italy). The results indicated that an increase of temperature, in the range between 1.3 and 2,5 °C, is expected in the next 100 years. The reference evapotranspiration (ETo) variations would follow a similar trend; as averaged over the whole region, the ETo increase would be about 15.4%. The precipitation will not change significantly on yearly basis although a slight decrease in summer months and a slight increase during the winter season are foreseen. The climatic water deficit (CWD) is largely caused by ETo increase, and it would increase over the whole Apulia region in average for more than 200 mm. According to Thornthwaite and Mather climate classification, the moisture index will decrease in the future, with decreasing of humid areas and increasing of aridity zones. The net irrigation requirements (NIR), calculated for ten major crops in the Apulia region, would increase significantly in the future. By the end of the 21st Century, the foreseen increase of NIR, in respect to actual situation, is the greatest for olive tree (65%), wheat (61%), grapevine (49%), and citrus (48%) and it is slightly lower for maize (35%), sorghum (34%), sunflower (33%), tomato (31%), and winter and spring sugar beet (both 27%)

Increasing productivity in irrigated agriculture: Agronomic constraints and hydrological realities

Irrigation is widely criticised as a profligate and wasteful user of water, especially in watershort areas. Improvements to irrigation management are proposed as a way of increasing agricultural production and reducing the demand for water. The terminology for this debate is often flawed, failing to clarify the actual disposition of water used in irrigation into evaporation, transpiration, and return flows that may, depending on local conditions, be recoverable. Once the various flows are properly identified, the existing literature suggests that the scope for saving consumptive use of water through advanced irrigation technologies is often limited. Further, the interactions between evaporation and transpiration, and transpiration and crop yield are, once reasonable levels of agricultural practices are in place, largely linear—so that increases in yield are directly and linearly correlated with increases in the consumption of water. Opportunities to improve the performance of irrigation systems undoubtedly exist, but are increasingly difficult to achieve, and rarely of the magnitude suggested in popular debate

A systematic and quantitative approach to improve water use efficiency in agriculture

As the competition for the finite water resources on earth increases due to growth in population and affluence, agriculture is faced with intensifying pressure to improve the efficiency of water used for food production. The causes for the relatively low water use efficiency in agriculture are numerous and complex, including environmental, biological, engineering, management, social, and economic facets. The complexity of the problem, with its myriads of local variations, requires a comprehensive conceptual framework of the underlying physical and biological processes as the basis to analyze the existing situation and quantify the efficiencies, and to plan and execute improvements. This paper proposes such a framework, based on the simple fact that the overall efficiency of any process consisting of a chain of sequential step is the product of the efficiency (i.e., output/input ratio) of its individual component steps. In most cases of water use, a number of process chains, both branching and merging, are involved. Means to integrate the diverging and converging chains are developed and presented as equations. Upscaling from fields to regions and beyond are discussed. This chain of efficiencies approach is general and can be applied to any process composed of chains of sequential steps. Here the framework is used to analyze the systems of irrigated and dryland crop production, and animal production on rangeland. Range of plausible efficiencies of each step is presented as tables, with values separately for the poor and for the good situation of circumstances, management and technology. Causes of the differences in efficiency of each step, going from water delivery to soil water extraction, transpiration, photosynthesis, and conversion to crop biomass and yield, and to animal product are briefly discussed. Sample calculations are made to demonstrate how modest differences in the efficiencies of the component steps are manifested as large to huge differences in the overall efficiency. Based on an equation quantifying the impact of changes in efficiency of component steps on the overall efficiency, it is concluded that generally, it is more effective to made modest improvements in several or more steps than to concentrate efforts to improve one or two steps. Hence, improvement efforts should be systematic and not overly concentrated on one or two components. The potential use of the same equation as the point of departure to optimize the allocation of economic resource among the component steps to maximize the improvement in the overall water use efficiency is elaborated on. The chain of efficiencies framework provides the means to examine the current levels of efficiency along the pathways of agricultural water use, to analyze where inefficiencies lie by comparing with the range of known efficiency values in the tables presented, to assess the potential improvements that may be achieved in various parts and their impact on the overall efficiency, and to aid in the optimal allocation of resources for improvements. © 2007 Springer-Verlag.The work of TCH is partly funded by the CGIAR Water and Food Challenge Program through ICARDA.Peer Reviewe