Document Type : Complete scientific research article
Authors
1
Agronomy Department, Gorgan Univ. Agric, Sci, & Natur. Resour., Gorgan, Iran
2
PhD student of Agroecology, Faculty of Plant Production, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
3
PhD Graduated in Crop Ecology, Gorgan University of Agricultural Sciences and Natural Resources
4
Gorgan University of Agricultural Sciences and Natural Resources , Gorgan, Iran
5
Agricultural Economics,Sari University of Agricultural Sciences and Natural Resources
Abstract
Background and objectives: More than half of the water withdrawal for agriculture in Iran is over-harvesting, which has caused huge damages to the country's environment. Therefore, there is an urgent need to implement water saving methods and to adapt to water scarcity. One of these methods is changing the cropping pattern, and it is necessary to examine its importance on a regional scale, such as a province. The purpose of this study was to estimate the applied irrigation water under farmers’ conditions in Golestan province and using the estimates to optimize the cropping pattern with the aim of minimizing water consumption/harvesting for agriculture. The current cropping pattern was optimized so that farmers’ profit remains the same and agricultural sustainability criteria were taken into account.
Materials and methods: The study area of the research was Golestan province and more than 30 agricultural plants of this province. The entire cultivated area of the province was divided into 10 agro-ecological zones and the growth, yield and irrigation water of agricultural plants were estimated using a crop model under farmers’ conditions in these zones with the help of a crop simulation model that was parameterized for the conditions of the farmers. Optimizing the cropping pattern was done with the aim of minimizing the amount of irrigation water applied under farmers' conditions in the entire province. It was also constrained that the farmers profits in the optimized pattern would not change and the area under cultivation of perennial plants and legumes, which play an important role in agricultural sustainability, would not decrease. With the exception of wheat and rice, the minimum area under cultivation of each plant was 40% of its current area and the maximum was 2.5 times the current area. For wheat, the minimum cultivated area was limited to 70% of its current area and the maximum was 2.5 times the current area, and for rice, the minimum cultivated area was limited to 20% of the current area and the maximum was limited to its current area.
Results: In the current cropping pattern, wheat (40%), rice (23%), cool-season oil crops (11%), warm-season oil crops (9%), cool-season fruit trees (5%) and barley (3%) and vegetables (3%) have the most important shares of the cultivated area inthe province. The most important changes in the cultivated area due to the optimization of the cropping pattern were an increase in wheat (23% increase compared to its current area), cool-season fruit trees (96%) and vegetables (138%) and a decrease in rice (77%), cool-season oil crops (60%), warm-season oil crops (22%), barley (60%) and grain maize (60%). In the current cropping pattern, the largest share of irrigation water in the province belonged to rice (64%), wheat (12%), warm-season oil crops (7%), cool-season fruit trees (5%) and vegetables (3%). Optimizing the cropping pattern caused the amount of irrigation water used in the province to decrease by 41% and reach from 1338 to 785 million m3 per year. The most important changes in the applied irrigation water were an increase in wheat (23% increase compared to its the current value), cool-season fruit trees (105%) and vegetables (143%) and a decrease in rice (77%), cool-season oil crops (60%), warm-season oil crops (19%) and grain maize (60%).
Conclusion: Optimizing cropping pattern alone could save almost two times the reduction in water use in agriculture section of the province intended by the Ministry of Energy. Considering that changing the cropping pattern is not a costly option and can be done with a series of policies and pricing, it is expected to be addressed more than before.
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