Managing water resources for crop production

Abstract

SUMMARYIncreasing crop production to meet the food requirements of the world's growing population will put great pressure on global water resources. Given that the vast freshwater resources that are available in the world are far from fully exploited, globall there should be sufficient water for future agricultural requirements. However, there are large areas where low water supply and high human demand may lead to regional shortages of water for future food production. In these arid and semi-arid areas, where water is a major constraint on production, improving water resource management is crucial if Malthusian disasters are to be avoided. There is considerable scope for improvement, since in both dryland and irrigated agriculture only about one-third of the available water (as rainfall, surface, or groundwater) is used to grow useful plants. This paper illustrates a range of techniques that could lead to increased crop production by improving agricultural water use efficiency. This may be achieved by increasing the total amount of water available to plants or by increasing the efficiency with which that water is used to produce biomass. Although the crash from the Malthusian precipice may ultimately be inevitable if population growth is not addressed, the time taken to reach the edge of the precipice could be lengthened by more efficient use of existing water resources.

Water resources and their use in food production systems

“…64, 2002 Water Policy Article 369 Table 1. Management practices available to increase the efficiency of water use at a field scale in rainfed and irrigated production systems (adapted from Gregory, 1989 andWallace andBatchelor, 1997 User involvement in scheme operation and maintenance; introduction of water pricing and legal frameworks to provide incentives for efficient water use and disincentives for inefficient use; introduction of integrated catchment management; improved training and extension ration is normalised with respect to the appropriate evaporative demand to give an index between 0 and 1. Figure 5 clearly shows that the scope for reducing E s by manipulating the size of the crop canopy was greatest on clayey soils with high (and frequent) rain showers and low evaporative demand and least on sands with low (and infrequent) rain and high evaporative demand.…”

“…Estimates of the water losses in irrigated and rainfed agriculture in semi-arid areas. Based on data given in Wallace and Batchelor (1997) and reproduced from Falkenmark et al (1998). approaching rainy season can also provide seasonally specific fertilizer recommendations that are modified as the season unfolds (Stewart, 1989).…”

“…Since water supply is limited in many areas and the cost of introducing irrigation systems to new lands is high, there will be continuing emphasis on increasing the efficiency with which water is converted to crop dry matter in both irrigated and rainfed production systems. This involves agronomic, technical, managerial and institutional factors (Wallace and Batchelor, 1997;Yudelman, 1998). Rainfed agriculture produces about two thirds of global crop production (Postel, 1993) and there is an important interaction in water and nutrient management that can lead to substantial increases in the field scale efficiency of water use and production at some locations (Gregory et al, 1997).…”

ARBUSCULAR MYCORRHIZAL COLONIZATION DOES NOT ALLEVIATE SODIUM CHLORIDE-SALINITY STRESS IN VINCA [CATHARANTHUS ROSEUS(L.) G. DON]

“…Environmental concerns and intensifying competition for municipal and industrial water will likely negatively affect the availability of low cost good quality water resources for the horticultural and landscape industry, and necessitate the utilization of low quality irrigation water, including waste water (Grieve et al, 2006;Hamdy et al, 2003;Oster, 1994;Rosegrant and Ringler, 1998;Shalhevet, 1994;Wallace and Batchelor, 1997). The use of reclaimed water represents a significant concern to plant production and landscape performance as it often is high in soluble salts (Lindsey et al, 1998).…”

Spatially and temporally explicit water footprint accounting

“…In sub-Saharan conditions, transpiration from rain-fed crops has been estimated to be 15 -30% of the rainfall (Wallace, 2000). Based on these analyses, Wallace and Batchelor (1997) and Wallace (2000) argue that there is plenty of scope for improving the efficiency level in agriculture, since normally in both rain-fed and irrigated agriculture only about one third of the available water is used to grow food.…”