Andrew D. Noble

The top 100 questions of importance to the future of global agriculture

Despite a significant growth in food production over the past half-century, one of the most important challenges facing society today is how to feed an expected population of some nine billion by the middle of the 20th century. To meet the expected demand for food without significant increases in prices, it has been estimated that we need to produce 70–100 per cent more food, in light of the growing impacts of climate change, concerns over energy security, regional dietary shifts and the Millennium Development target of halving world poverty and hunger by 2015. The goal for the agricultural sector is no longer simply to maximize productivity, but to optimize across a far more complex landscape of production, rural development, environmental, social justice and food consumption outcomes. However, there remain significant challenges to developing national and international policies that support the wide emergence of more sustainable forms of land use and efficient agricultural production. The lack of information flow between scientists, practitioners and policy makers is known to exacerbate the difficulties, despite increased emphasis upon evidence-based policy. In this paper, we seek to improve dialogue and understanding between agricultural research and policy by identifying the 100 most important questions for global agriculture. These have been compiled using a horizon-scanning approach with leading experts and representatives of major agricultural organizations worldwide. The aim is to use sound scientific evidence to inform decision making and guide policy makers in the future direction of agricultural research priorities and policy support. If addressed, we anticipate that these questions will have a significant impact on global agricultural practices worldwide, while improving the synergy between agricultural policy, practice and research. This research forms part of the UK Governments Foresight Global Food and Farming Futures project.

Phytoremediation of Sodic and Saline‐Sodic Soils

Sodicity-induced soil degradation is a major environmental constraint with severe negative impacts on agricultural productivity and sustainability in arid and semiarid regions. As an important category of salt-affected soils, sodic soils are characterized by excess levels of sodium ions (Naþ) in the soil solution phase as well as on the cation exchange complex, exhibiting unique structural problems as a result of certain physical processes (slaking, swelling, and dispersion of clay) and specific conditions (surface crusting and hardsetting). Saline-sodic soils, another category of salt-affected soils, are generally grouped with sodic soils because of several common properties and management approaches. Sodic and saline-sodic soils occur within the boundaries of at least 75 countries, and their extent has increased steadily in several major irrigation schemes throughout the world. The use of these soils for crop production is on the increase as they are a valuable resource that cannot be neglected, especially in areas where significant investments have already been made in irrigation infrastructure. It is imperative to find ways to improve sodic and saline-sodic soils to ensure that they are able to support highly productive land-use systems to meet the challenges of global food security.

Economics of salt-induced land degradation and restoration

Food security concerns and the scarcity of new productive land have put productivity enhancement of degraded lands back on the political agenda. In such a context, salt‐affected lands are a valuable resource that cannot be neglected nor easily abandoned even with their lower crop yields, especially in areas where significant investments have already been made in irrigation and drainage infrastructure. A review of previous studies shows a very limited number of highly variable estimates of the costs of salt‐induced land degradation combined with methodological and contextual differences. Simple extrapolation suggests that the global annual cost of salt‐induced land degradation in irrigated areas could be US

Variable Charge Soils: Their Mineralogy, Chemistry and Management

27.3 billion because of lost crop production. We present selected case studies that highlight the potential for economic and environmental benefits of taking action to remediate salt‐affected lands. The findings indicate that it can be cost‐effective to invest in sustainable land management in countries confronting salt‐induced land degradation. Such investments in effective remediation of salt‐affected lands should form part of a broader strategy for food security and be defined in national action plans. This broader strategy is required to ensure the identification and effective removal of barriers to the adoption of sustainable land management, such as perverse subsidies. Whereas reversing salt‐induced land degradation would require several years, interim salinity management strategies could provide a pathway for effective remediation and further showcase the importance of reversing land degradation and the rewards of investing in sustainable land management.

Remediation of Abandoned Saline Soils Using Glycyrrhiza glabra: A Study from the Hungry Steppes of Central Asia

Soils in the Oxisols, Ultisols, Alfisols, Spodosols and Andisols orders that are rich in constituents with surface reactive groups with amphoteric properties are considered variable charge soils (VCS). They have developed under intensive weathering in subtropical and tropical regions or from volcanic ash parent material. The magnitude and sign of the surface charge of variable charge constituents depend on the chemistry of the contacting solution (pH and ionic strength). The mineralogical, physical and chemical characteristics of these soil systems are different from those observed in soil systems of temperate regions. In this chapter, the mineralogy, chemistry and management of VCS are reviewed and discussed, focusing on the chemistry of these systems.

Improvement in Water-Holding Capacity and Structural Stability of a Sandy Soil in Northeast Thailand

Large expansion of the irrigated area in the Aral Sea Basin has exacted a substantial toll on land and water resources in the region. Elevated water tables associated with poor irrigation management and inappropriate drainage infrastructure have resulted in significant secondary salinisation of crop lands resulting in declining cotton and wheat yields and eventual abandonment of lands. Costs associated with the installation of appropriate drainage infrastructure in order to reclaim these areas are prohibitive and hence alternative approaches are required that can be adopted by resource poor farmers. In the current study the potential use of Glycyrrhiza glabra (common name liquorice) to reclaim abandoned saline areas was assessed over a four year period before being returned to a cotton/wheat crop rotation. Two adjacent abandoned fields of 10 and 13 ha respectively were selected for the study on which two treatments were imposed, namely, a control that was maintained as a bare fallow between 1999 and 2003 and a treated plot where liquorice was established over this period. High quality livestock forage with a protein content of 12% was cut from the liquorice plot with dry matter yields ranging from 3.66 (±0.06) to 5.11 (±0.17) t ha−1. In addition, root dry matter yields of 5.63 (±1.19) to 8.55 (±0.82) t ha−1 were recorded, this plant component being used in the preparation of herbal medicines and soft drinks. At the end of four years both plots were returned to a wheat and cotton crop rotation. Yields of wheat on the control and treated plots were 0.87 (±0.05) and 2.42 (±0.02) t ha−1 respectively. Similarly substantial increases in cotton were observed with the control and treated plots yielding 0.31 (±0.01) and 1.89 (±0.18) t ha−1. These levels of production on the treated plot exceed the district average for wheat and cotton of 1.75 and 1.5 t ha−1 respectively, clearly showing the positive benefit associated with the growing of liquorice. Water table levels after four years were maintained below the critical level of 2.5 m in the treated plots whilst rising to within 1.99 m from the surface in the control. Salt content of the soil in the treated plot declined over the study while those in the control increased. This preliminary study has clearly demonstrated the ameliorating affect of liquorice in bringing abandoned salt affected soils back into production that is low cost and could be adopted by resource poor farmers.

An integrated agro-ecosystem and livelihood systems approach for the poor and vulnerable in dry areas

Light textured sandy soils in northeast Thailand are often highly weathered and degraded resulting in low nutrient and water holding capacities. The latter is further complicated by the structural instability of these soils. Field based soil amelioration studies were undertaken in order to evaluate local traditional practices currently adopted by farmers and innovative approaches to improve the productivity of these soils. The treatments included: composted leaf litter, termite mound material, and bentonite. In the present study, physical properties associated with water holding capacity and soil structural stability of an upland soil of the Satuk series in Northeast Thailand were investigated two years after the application of these amendments. Although changes in silt and clay fraction were small, the application of these amendments enhanced porosity and altered the pore size distribution resulting in an increase in the available water content for crop growth. In particular, increases in the available water content were remarkably higher under termite mound material (0.21 m3 m−3) and bentonite (0.19 m3 m−3) treatments when compared to the control (0.14 m3 m−3). However, soil structural stability remained poor for the compost and termite mound material treatments, while the structural stability was enhanced for the bentonite treatment. Enhanced soil structural stability observed in the bentonite treatment accounted for the persistence in increased water holding capacity, and this will have positive benefits to the rainfed cropping systems that are susceptible to periodic drought stress, thereby reducing risk of crop failure associated with low water holding capacity.

Tropical deltas and coastal zones: food production, communities and environment at the land-water interface

More than 400 million people in the developing world depend on dryland agriculture for their livelihoods. Dryland agriculture involves a complex combination of productive components: staple crops, vegetables, livestock, trees and fish interacting principally with rangeland, cultivated areas and watercourses. Managing risk and enhancing productivity through diversification and sustainable intensification is critical to securing and improving rural livelihoods. The main biophysical constraints are natural resource limitations and degradation, particularly water scarcity and encroaching desertification. Social and economic limitations, such as poor access to markets and inputs, weak governance and lack of information about alternative production technologies also limit the options available to farmers. Past efforts to address these constraints by focusing on individual components have either not been successful or are now facing a declining rate of impact, indicating the need for new integrated approaches to research for development of dryland systems. This article outlines the characteristics of such an approach, integrating agro-ecosystem and livelihoods approaches and presents a range of empirical examples of its application in dryland contexts. The authors draw attention to new insights about the design of research required to accelerate impact by integrating across disciplines and scales.

Development of magnesium-dominant soils under irrigated agriculture in southern Kazakhstan.

The dynamics of aquatic resources in the canals of Bac Lieu Province, in southern Vietnam, are detailed and synthesized in this study. Nekton and eight environmental parameters were monitored in this province between 2004 and 2006, at 14 sites sampled three times a year. The study area, located along the coastal zone, is characterized by a variable environment subject to saline, freshwater and acidic pulses. The spatiotemporal dynamics of aquatic resources and their relationships with environmental parameters are detailed. The dominance of either freshwater or estuarine fauna, the dynamics of assemblages and the catches of fishers appear to be largely influenced by the management of sluice gates built along the coastal zone.

Land degradation and water productivity in agricultural landscapes

ABSTRACT Irrational irrigation practices in the Arys Turkestan Canal command area in the southern part of Kazakhstan have led to the formation of soils with poor physical and chemical properties. To study whether irrigation and leaching practices and/or groundwater rise have contributed to the accumulation of Mg 2+ on the cation exchange complex of these soils, historical changes in soil and groundwater quality were used as source data and the Visual MINTEQ model was applied to analyze the chemical composition of water and soils in the study area. The imposed irrigation regime and the leaching of light sierosem soils led to the dissolution and subsequent leaching of inherent gypsum and organic matter from the soil profile. Further, the domination of bicarbonate in the irrigation water promoted weathering of the carbonate minerals present as calcite. The higher concentrations of Mg 2+ in comparison to Ca 2+ in the irrigation water resulted in the replacement of Na + by Mg 2+ on the cation exchange complex. In the lower part of the command area, shallow groundwater has contributed to the accumulation of Na + and to a large extent of Mg 2+ on the cation exchange sites.