R. Lal
The world population of 6.5 billion in 2006 is expected to reach 7 billion in 2010, 8 billion in 2025 and 10 - 12 billion by 2100, with most of the expected increase to occur in developing countries. The world's food insecure population is estimated at 730 million in 2005 and 680 million in 2010, of which 200 million are in Africa, and 3.7 billion are at risk of hidden hunger. Agricultural sustainability is closely linked with availability and quality of water and soil. Water use for urban, industrial and agricultural use, respectively, was 20, 30 and 350 km3 yr-1 in 1900, and 440, 1900 and 3400 km3 yr-1 in 2000. Population affected by water scarcity was 130 million in 1990, 436 million in 1995 and projected to be 800 million in 2025 and 3950 million in 2050. Per capita agricultural land availability in 1990 and 2025, respectively, is estimated at 0.05 and 0.03 ha in Egypt, 0.10 and 0.04 ha in Kenya, 0.33 and 0.05 ha in Tanzania, 0.35 and 0.07 ha in Pakistan, 0.20 and 0.12 ha in India, 0.09 and 0.05 ha in Bangladesh, 0.32 and 0.08 ha in Indonesia, 0.32 and 0.06 ha in China and 0.33 and 0.08 ha in the Philippines. Land scarcity is exacerbated by the severe problem of soil degradation in developing countries. Global land area affected by degradation is estimated by ISRIC at 1094 Mha by water erosion, 548 Mha by wind erosion, 240 Mha by chemical and 83 Mha by physical processes. Of these, percentage of degraded areas occurring in developing countries is 77 for water erosion, 83 for wind erosion, 89 for chemical degradation and 53 for physical degradation. Soil degradation depletes the soil organic carbon (SOC) pool leading to emission of CO2 into the atmosphere. Compared with 270 ± 30 Pg C emitted into the atmosphere through fossil fuel combustion, 136 ± 55 Pg were contributed through terrestrial ecosystems, of which 78 ± 12 Pg came through depletion of the SOC pool. Sustainable horticultural practices, similar to grain crops, include mulching with crop residues and synthetic materials, growing cover crops, water harvesting, and conservation tillage or even no-till farming. The objective is to enhance soil quality and alleviate soil and environmental constraints to increasing production. Sustainable management of natural resources must be based on enhancing productivity per unit area; time and energy input; maintaining a positive trend in productivity over time; creating SOC sink capacity of natural and managed ecosystems; reducing risks of non-point source pollution and sedimentation; and making managed ecosystems a solution to environmental problems. Relevant indices of sustainable horticulture and resource management include soil quality and resilience and factors affecting them, and temporal changes in productivity, and use efficiency of non-renewable or input of limited resources.
DOI: 10.17660/ActaHortic.2008.767.1
food insecurity, soil quality, soil degradation, soil restoration, per capita land area, sustainability indices

Acta Horticulturae