Managing water by managing land: Addressing land degradation to improve water productivity and rural livelihoods § Deborah Bossio a, *, Kim Geheb b , William Critchley c a International Water Management Institute (IWMI), P.O. Box 2075, 127 Sunil Mawatha, Battaramulla, Sri Lanka b International Water Management Institute, P.O. Box 5689, Addis Ababa, Ethiopia c Natural Resource Management Unit, CIS/Centre for International Cooperation, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands 1. Introduction Land degradation reduces water productivity at field and landscape scales, and affects water availability, quality, and storage. Because of this strong link between land and water productivity, improving water management in agriculture requires that land degradation be mitigated or prevented. Optimistic scenarios suggest that, by 2050, 30–40% more fresh water will be used by agriculture than is used today (De Fraiture et al., 2007). If, however, agricultural water productivity does not improve, the agricultural sector will consume an additional 70–90%. In this review of global experiences relating to land degradation, we highlight important degradation processes that are closely linked to water use and management, underlying drivers of that degradation, and review options that can help mitigate land degradation to improve water productivity. 2. The land–water connection Despite being conducted during the 1980s, the Global Assess- ment of Human-induced Soil Degradation (GLASOD) (Oldeman, 1991) remains the only uniform global source of degradation data. According to GLASOD estimates, degradation of cropland appears to be most prevalent in Africa, affecting 65% of cropland areas, compared with 51% in Latin America and 38% in Asia. Degradation of pasture is also most serious in Africa, affecting 31% of pastureland, compared with 20% in Asia and 14% in Latin America. Forestland degradation is most pronounced in Asia, affecting 27% of forestlands, compared with 19% in Africa and 14% in Latin America. Based on GLASOD, Wood et al. (2000) estimated that 40% of the world’s agricultural land is moderately degraded, and a further 9% strongly degraded, reducing global crop yield by 13%. Estimates of land use degradation rates are even more uncertain than degradation extent estimates, and vary from 5 to 10 million Agricultural Water Management xxx (2009) xxx–xxx ARTICLE INFO Article history: Available online xxx Keywords: Land use management Land degradation Water management Water productivity ABSTRACT The premise of this paper is that the key to effective water resources management is understanding that the water cycle and land management are inextricably linked: that every land use decision is a water use decision. Gains in agricultural water productivity, therefore, will only be obtained alongside improvements in land use management. Expected increases in food demands by 2050 insist that agricultural production – and agricultural water use – must increase. At the same time, competition for water between agricultural and urban sectors will also increase; and the problem is further compounded by land degradation. A global survey suggests that 40% of agricultural land is already degraded to the point that yields are greatly reduced, and a further 9% is degraded to the point that it cannot be reclaimed for productive use by farm level measures. Soil erosion, nutrient depletion and other forms of land degradation reduce water productivity and affect water availability, quality, and storage. Reversing these trends entails tackling the underlying social, economic, political and institutional drivers of unsustainable land use. This paper is based on a review of global experiences, and its recommendations for improving water management by addressing land degradation include focusing on small scale agriculture; investing in rehabilitating degraded land to increase water productivity; and enhancing the multifunctionality of agricultural landscapes. These options can improve water management and water productivity, while also improving the livelihoods of the rural poor. ß 2009 Elsevier B.V. All rights reserved. § This paper is based on a chapter by Bossio et al. (2007). * Corresponding author. E-mail address: d.bossio@cgiar.org (D. Bossio). G Model AGWAT-2730; No of Pages 7 Please cite this article in press as: Bossio, D., et al., Managing water by managing land: Addressing land degradation to improve water productivity and rural livelihoods. Agric. Water Manage. (2009), doi:10.1016/j.agwat.2008.12.001 Contents lists available at ScienceDirect Agricultural Water Management journal homepage: www.elsevier.com/locate/agwat 0378-3774/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2008.12.001