Microeconomics of Deficit Irrigation and Subjective Water Response Function for Intensive Olive Groves

Abstract

This research paper analyzes the economics of deficit irrigation based on the use of subjective estimates of the crop yield-water relationship to determine water supply in irrigated olive groves. Interviewed farmers were asked to give three estimates for the yield-water relationship as a function of water supply (full irrigation, usual deficit irrigation and extreme deficit irrigation). Those responses are contrasted with the actual irrigation dose and the results appear to support the hypothesis that a majority of farmers use deficit irrigation as a strategy that maximizes the value of limited water input rather than the conventional microeconomic behavior of maximizing the return to land.

Agricultural Irrigation Water Use in a Closed Basin and the Impacts on Water Productivity: The Case of the Guadalquivir River Basin (Southern Spain)

“…As we have previously mentioned, a distinctive feature of the Guadalquivir RB, besides the higher water-use efficiency due to modern irrigation techniques, is the widespread adoption of DI practices, especially among olive farmers [16]. This trend, which was initially observed in olive groves, is now extending to other Mediterranean crops such as almonds, which have begun to use DI techniques as they replace other less productive herbaceous and woody crops.…”

“…The area occupied by olive and citrus crops has registered a considerable increase, while other irrigated crops such as cotton, corn and sugar beet report a significantly reduced presence in the basin. In parallel, the average irrigation water application in the basin fell by approximately 600 m 3 /ha between 2005 and 2012, which affected most of the crops but had a particularly notable impact on traditional olive groves, where the use of DI techniques is more widespread [16]. Table 3 also shows the annual relative irrigation supply (ARIS), i.e., the ratio of water applied to water required, for major crops in the basin; the figures reveal an overall reduction in these ratios for most crops.…”

“…In this scenario dominated by increasing pressures on water demand and a growing scarcity of the resource, the Guadalquivir RB has reached a state of closure, with no additional water resources to be consumed. With respect to DI and new crops, Expósito and Berbel [16] study a sample of olive farmers in the Guadalquivir RB and conclude that the model that best explains their behavior centers on the maximisation of the value of the marginal product of water, considering it to be the true limiting factor of production. This is contrary to traditional theory that considers land as the limiting factor.…”

Deficit Irrigation and Partial Root-Zone Drying Techniques in Processing Tomato Cultivated under Mediterranean Climate Conditions

“…The frequency and severity of prolonged periods of heat and drought stress, in fact, is expected to increase in the future in semi-arid Mediterranean areas [2,3]. Moreover, as reported by Expósito and Berbel [52], the extensive adoption of deficit irrigation techniques could have great consequence at basin or aquifer levels, requiring further research.…”

Sustainability Implications of Deficit Irrigation in a Mature Water Economy: A Case Study in Southern Spain

“…In their model of DI, Berbel and Mateos [9] expanded the model developed by English [10] to account for DI, by including in the agro-economic model efficiency changes where water rather than land is the limiting factor. Following this development, Expósito and Berbel [20], using estimates obtained from a sample of olive farmers in Southern Spain whose individual responses consisted of the extensive use of DI practices, compared the actual irrigation volume that a farmer applies to a crop with the solutions to the optimisation problem. The findings presented in the next section show that these irrigation practices represent the farmers' primary response and a way to optimise water value (i.e., the productive value per unit of water used), while minimising the effects on farmers' net income of future increases in water-related costs, as well as those stemming from further supply restrictions.…”