Reliable food production relies on consistent water availability. The last two decades have provided a deeper understanding of the role of trees and forests in ensuring this water supply. In this chapter, I highlight the links between trees and water security, an indispensable element of food security. We now know that, in many contexts, trees can improve water access and reliability. Achieving the right densities of the right trees in the right places can increase soil water recharge and maintain dependable baseflow. On a larger scale, atmospheric processes are key, and expanding tree cover can render regions wetter and more productive, yielding more predictable rainfall through enhanced atmospheric moisture import and recycling. Opportunities and implications vary with local circumstances. While new insights raise new questions and research remains essential, existing knowledge can guide land-use policy, planning and practices. The large-scale relationships between tree cover and water cause significant threats if tree cover declines but offer substantial opportunities when forests are preserved and extended. Although forests and trees provide many valuable goods and services to local communities, economies and the planet, any alterations in tree cover can effect water availability, directly impacting food production. Can we boost water security and maximise the wider benefits of tree cover while increasing food production? This chapter emphasises that trees are neither a luxury consideration nor a minor footnote when we consider food security but rather a foundation for achieving it.

Motivation: Breaking through the constraints of water scarcity is a crucial factor for the efficient and sustainable production of food in China. Objective: To explore a new strategy to alleviate the water resource pressure in food production in China, based on the theory of resource flow, this study empirically explores the relationship between food imports and the water pressure in food production in China from the perspective of virtual water trade. Data and Method: This study collects panel data from 30 provincial-level administrative regions in China from 2003 to 2020 and employs methods such as the two-way fixed effects model, instrumental variable approach, and spatial Durbin model for empirical analysis. Results: (1) China’s net food imports surged from −0.000397 billion tons (Bt) in 2003 to 0.118325 Bt in 2020, with a rapid annual growth rate of about 9.37%. Changes in net imports are accompanied by virtual water flows. Between 2003 and 2020, the virtual water content of China’s net food imports increased from 31.7086 Bt to 187.7511 Bt, a yearly increase of 10.39%. (2) Virtual water for food imports has a mitigating effect on the water pressure in food production. Every 0.100 Bt of virtual water imported will reduce the water pressure in food production index by 0.026. The impact has a spatial spillover effect. Moreover, as there is high pressure on water resources in food production in northern regions and major grain-producing areas, the mitigating effect of food imports on the pressure of water resources in food production is also enhanced. The quantile regression found that as the water pressure in food production increases, the mitigating effect of virtual water for food imports on the water pressure in food production gradually increases. Implications: This study examines the relevance of resource flow theory within the context of food trade, thereby broadening the scope of research on virtual water trade in food. Additionally, this study offers valuable insights for the development of strategies aimed at mitigating the pressure on water resources associated with food production in China.

Studying the water-emissions-food nexus (WEF Nexus) is crucial for the sustainability of agricultural economic systems. The multi-regional input–output (MRIO) model provides insights for water-emissions-food integrated collaborative management. This study develops a detailed agriculture-oriented MRIO model based on the RAS method, which disaggregates the agricultural sector into 12 sub-sectors. The water consumption and greenhouse gas (GHG) emissions are allocated to the entire supply chain to identify the key regions and routes of the WEF Nexus in China for 2017. Then the environmental output level of the agricultural sector and its sub-sectors is analyzed using productivity indicators. Results demonstrate that the agricultural sector exhibits a strongly connected WEF Nexus (coefficient of 0.87), particularly in Coastal and Southwest regions. The synergistic relationship between water and emissions suggests significant opportunities for implementing integrated management strategies. 73.3% of virtual water and 71.7% of embodied emissions are concentrated in downstream non-agricultural sectors of supply chains, highlighting the substantial impact of trade transmission on the environment. The water and emissions productivity in the agricultural sector are spatially aligned except in the Central and Southwest regions. As significant agricultural output regions, Northeast and Central regions have lower water or emissions productivity, making sustainable agricultural development more challenging. Therefore, practical measures should focus on promoting technological innovation and its adoption to enhance water use efficiency and reduce GHG emissions in agricultural production.

Irrigated agriculture is an important contributor to African food security, both for farmers directly and for the urban population and wider economy. This chapter argues that the irrigated area in Africa is much larger than generally thought, but still much smaller than it could be. We also explore the concept of irrigation potential and show that it is not a static number, but depends on economic context and people’s abilities to develop irrigation. It is important to also consider that irrigation can be partial or for protection against droughts. The potential of irrigation to contribute to Africa’s food security depends not only on developing water resources, but even more so on an approach that focuses on inclusion and optimization to get the most benefits for most people. The concluding section presents five areas where work can be done radically differently to support a much faster development of water-based agricultural intensification.

Agricultural cooperatives are widely regarded as effective institutions for supporting smallholder farmers, reducing poverty, and improving food security. However, empirical evidence varies with mixed findings across different contexts. This study used a primary data of 820 farm households to examine the relationship between membership of water user association (WUA) and food security, using a quasi-experimental research design. The findings show that WUA membership is significantly influenced by factors including age, marital status, access to extension services, participation in supplementary irrigation (SI) and drought index insurance (DII) initiatives, farm size, and an asset aspiration gap. The results further indicate a positive association between WUA participation and household food security. These findings suggest that rural development policies should focus on strengthening existing WUAs and fostering the establishment of new ones through inclusive approaches that address food insecurity.

It is widely acknowledged that the world is currently experiencing an unprecedented water shortage, with agriculture being a crucial contributor. This paper presents a synthesis of available evidence, identify knowledge gaps, and make a state-of-the-art synthesis on green water management in Ethiopia. A systematic review methodology was implemented, encompassing the compilation and analysis of peer-reviewed and gray literature. The paper demonstrates that rainfed agriculture, which relies on “green water” (soil moisture from rainfall), accounts for 80% of cultivated land and 60-70% of global crop production. However, green water management has not received adequate attention in water policy and land rehabilitation programs in Ethiopia, where irrigation is limited. The analysis reveals a large yield gap and water productivity gap for major crops like maize, sorghum, and wheat in Ethiopia’s rainfed agriculture. Increasing crop yields through better soil, water, and crop management practices can significantly improve water productivity, offering “windows of opportunity” to enhance food and water security. Thus, a paradigm shift from the traditional narrow focus on soil erosion control towards an integrated green-blue water management approach in water and agricultural policies and programs is urgently required. Increased investments and expertise in green water management at the government level are crucial. Optimizing the use of green water resources in rainfed farming can also unlock Ethiopia’s export potential while improving domestic water and food security through strategic virtual water trade. In conclusion, the review highlights unlocking the potential of green water resources through targeted investments and policy support for rainfed agriculture can significantly contribute to Ethiopia’s water and food security objectives in a cost-effective and environmentally sustainable manner.

The synergistic relation among land resources, water resources, and food production plays a crucial role in sustainable agricultural development. This research constructs a coupling coordination assessment system of the land–water–food (LWF) nexus from 2005 to 2020 for 31 provinces (municipal cities, autonomous regions) in China, and explores the current development status of land, water, and food systems at multiple scales as well as the coupling coordination characteristics of the LWF nexus. The exploring spatial data analysis and spatial Tobit model are used to explain the spatial correlations and influencing factors of coupling coordination development on the LWF nexus. On that basis, the gray GM (1,1) model is used to forecast the future development of the LWF nexus in China. The results show that the comprehensive development indexes of the land system, water system, food system, and LWF nexus are on the rise, but the land system lags behind the water system and food system. The coupling coordination degree of the LWF nexus in different regions ranges from 0.538 to 0.754, and the coupling coordination development of the LWF nexus in China has reached the preliminary coupled coordination type, with an evolutionary process similar to that of its comprehensive development level. Further empirical research shows that there is a significant positive spatial correlation between coupling coordination development levels for the LWF nexus in China. The level of urbanization and agricultural industry agglomeration have negative effects, while economic development, ecological environment, and scientific and technological progress have positive effects. The prediction results indicate that the coupling coordination degree of the LWF nexus in China will show a stable upward trend from 2024 to 2025, and most provinces will reach the intermediate coupled coordination type in 2025. This study can inform decision-making for policy-makers and practitioners and enrich the knowledge hierarchy of the LWF nexus’ sustainable development on the national and regional scales.

Phytosterols (PS) offer significant health benefits in human diet, but its poor solubility limits its effectiveness and application. This study explored enhancing PS solubility by testing thirteen food-grade coformers, three preparation methods and proportions screening to obtain the optimal formulation. Nicotinamide (Nic) was identified as the most effective coformer. A 20:1 (w/w) PS-Nic co-amorphous (CM) mixture, prepared via freeze-drying, achieved a solubility of 1536.4 μg/mL, significantly higher than pure PS. X-ray diffraction and differential scanning calorimetry confirmed the amorphous state of the mixture. Fourier-transform infrared, Raman, and 1H NMR spectroscopies, along with molecular dynamics simulations, revealed strong intermolecular interactions between PS and Nic. The PS-Nic CM demonstrated up to 60% in vitro dissolution and release within 2 h and maintained stable after storage at 4 °C for 6 months and under accelerated conditions equivalent to 10 months at room temperature. In sum, the crystal structure of PS was altered, and formed a co-amorphous system by using Nic as the optimal ligand via lyophilization to increase solubility. These findings suggest that the PS-Nic CM system has potential applications in functional foods, offering a feasible strategy to enhance the bioavailability of PS.

With climate change and ongoing socioeconomic development, issues related to water, energy, and food security are becoming more pressing, threatening human well-being. Under the influence of environmental factors, water–energy–food resources exhibit significant spatial heterogeneity. However, limited information exists on how water–energy–food services and their interactions respond to various environmental gradients. Using the Songhua River Basin as a case study, this study quantified the spatiotemporal variation and interaction between water–energy–food services (water yield, net primary productivity, and food production) from 2001 to 2020, investigated changes in water–energy–food services and their interactions with each environmental gradient (elevation, precipitation, temperature, and vegetation cover) using a generalized additive model, and explored the underlying mechanism of interactions between water–energy–food services under different environmental gradients based on a structural equation model. The results indicated that water, energy, and food services increased significantly (p < 0.01) by 4.33 mm/yr, 4.09 gC/m2·yr, and 0.06 t/ha·yr, respectively. A trade-off between water–energy services was observed in 12.36 % of the southern regions. Water–energy–food services exhibited distinct nonlinear changes with multiple environmental gradients, with several key threshold inflection points identified. As elevation and precipitation increased, the synergy between water–energy services weakened, shifted to a trade-off, and then strengthened. Human activities contributed to water–food services but restricted energy services. Photosynthesis, evapotranspiration, and vegetation cover were identified as the main factors influencing the interactions between water, energy, and food services, driven by competitive relationships under different environmental gradients. This study provides a significant basis for ecosystem management strategies under various environmental gradients.

This paper introduces and applies iGain4Gains, an Excel-based model, to reveal how changes to water conservation and allocation, and irrigation technology, can produce four nexus gains. These gains are; reduced aggregate water consumption, sustained crop production, lower carbon emissions, and enhanced water availability for nature. We developed the model with limited data and hypothetical future scenarios from the Amman–Zarqa basin in Jordan. Given its significant irrigation and urban water demands and difficult decisions regarding future water allocation and nexus choices, this basin is a highly appropriate case study. The paper’s primary aim is to demonstrate the iGains4Gains nexus model rather than to build an accurate hydrological model of the basin’s water resources. The model addresses two critical questions regarding increased irrigation efficiency. First, can irrigation efficiency and other factors, such as irrigated area, be applied to achieve real water savings while maintaining crop production, ensuring greenhouse gas emission reductions, and ‘freeing’ water for nature? Second, with the insight that water conservation is a distributive/allocative act, we ask who between four paracommoners (the proprietor irrigation system, neighbouring irrigation systems, society, and nature) benefits hydrologically from changes in irrigation efficiency? Recognising nexus gains are not always linear, positive and predictable, the model reveals that achieving all four gains simultaneously is difficult, likely leading to trade-offs such as water consumption rebounds or increased carbon emissions. Demonstrated by its use at a workshop in Jordan in February 2024, iGains4Gains can be used by students, scientists and decision-makers, to explore and understand nexus trade-offs connected to changes in irrigation management. The paper concludes with recommendations for governing water and irrigated agriculture in basins where large volumes of water are withdrawn and depleted by irrigation.