Iran's Land Suitability for Agriculture

www.nature.com/scientificreports OPEN Iran’s Land Suitability for Agriculture Mohsen B. Mesgaran1, Kaveh Madani 2, Hossein Hashemi3,4 & Pooya Azadi1 Increasing population has posed insurmountable challenges to agriculture in the provision of future Received: 10 March 2017 food security, particularly in the Middle East and North Africa (MENA) region where biophysical Accepted: 6 July 2017 conditions are not well-suited for agriculture. Iran, as a major agricultural country in the MENA Published: xx xx xxxx region, has long been in the quest for food self-sufciency, however, the capability of its land and water resources to realize this goal is largely unknown. Using very high-resolution spatial data sets, we evaluated the capacity of Iran’s land for sustainable crop production based on the soil properties, topography, and climate conditions. We classifed Iran’s land suitability for cropping as (million ha): very good 0.4% (0.6), good 2.2% (3.6), medium 7.9% (12.8), poor 11.4% (18.5), very poor 6.3% (10.2), unsuitable 60.0% (97.4), and excluded areas 11.9% (19.3). In addition to overarching limitations caused by low precipitation, low soil organic carbon, steep slope, and high soil sodium content were the predominant soil and terrain factors limiting the agricultural land suitability in Iran. About 50% of the Iran’s existing croplands are located in low-quality lands, representing an unsustainable practice. There is little room for cropland expansion to increase production but redistribution of cropland to more suitable areas may improve sustainability and reduce pressure on water resources, land, and ecosystem in Iran. Increasing population and consumption have raised concerns about the capability of agriculture in the provision of future food security1, 2. Te overarching efects of climate change pose further threats to the sustainability of agricultural systems3, 4. Recent estimates suggested that global agricultural production should increase by 70% to meet the food demands of a world populated with ca. 9.1 billion people in 20505. Food security is particularly concerning in developing countries, as production should double to provide sufcient food for their rapidly growing populations5, 6. Whether there are enough land and water resources to realize the production growth needed in the future has been the subject of several global-scale assessments7–9. Te increase in crop production can be achieved through extensifcation (i.e. allocating additional land to crop production) and/or intensifcation (i.e. producing a higher yield per unit of land)7. At the global scale, almost 90% of the gain in production is expected to be derived from improvement in the yield, but in developing countries, land expansion (by 120 million ha) would remain a signifcant contributor to the production growth5, 10. Land suitability evaluations10, yield gap analysis8, 11, and dynamic crop models9 have suggested that the sustainable intensifcation alone or in conjugation with land expansion could fulfl the society’s growing food needs in the future. Although the world as a whole is posited to produce enough food for the projected future population, this envisioned food security holds little promise for individual countries as there exist immense disparities between regions and countries in the availability of land and water resources, and the socio-economic development. Global Agro-Ecological Zone (GAEZ v3.0) analysis12 suggests that there are vast acreages of suitable but unused land in the world (about 1.4 billion ha) that can potentially be exploited for crop production; however, these lands are distributed very unevenly across the globe with some regions, such as the Middle East and North Africa (MENA), deemed to have very little or no land for expansion. Likewise, globally available fresh water resources exceed current agricultural needs but due to their patchy distribution, an increasing number of countries, particularly in the MENA region, are experiencing severe water scarcity10. Owing to these regional diferences, location-specifc analyses are necessary to examine if the available land and water resources in each country will sufce the future food requirements of its nation, particularly if the country is still experiencing signifcant population growth. 1Stanford Iran 2040 Project, Hamid and Christina Program in Iranian Studies, Stanford University, Stanford, CA, 94305, USA. 2Centre for Environmental Policy, Imperial College London, London, SW7 2AZ, UK. 3School of Earth, Energy, and Environmental Sciences, Geophysics Department, Stanford University, Stanford, CA, 94305, USA. 4Center for Middle Eastern Studies and Department of Water Resources Engineering, Lund University, Lund, Sweden. Correspondence and requests for materials should be addressed to P.A. (email: [email protected]) SCIENTIFIC REPORTS | 7: 7670 | DOI:10.1038/s41598-017-08066-y 1 www.nature.com/scientificreports/ Suitability Soil + Topography + Rainfed class* Soil + Topography Climate Soil + Topography + Climate Excluded Areas 19.3 (11.9%) 19.3 (11.9%) 19.3 (11.9%) Unsuitable 39.7 (24.4%) 112.9 (69.5%) 97.4 (59.9%) Very Poor 55.7 (34.3%) 3.6 (2.2%) 10.2 (6.3%) Poor 24.8 (15.3%) 8.8 (5.4%) 18.5 (11.4%) Medium 17.2 (10.6%) 12.4 (7.6%) 12.8 (7.9%) Good 5.1 (3.1%) 4.8 (3.0%) 3.6 (2.2%) Very Good 0.7 (0.4%) 0.7 (0.4%) 0.6 (0.4%) Total area 162.5 162.5 162.5 Table 1. Area (million ha) and percentage of Iran’s land within agricultural suitability classes based on three suitability analysis criteria. Also shown is the total area of lands excluded from the analysis. *See Table 3 for the defnition of suitability classes. Suitability index (SI) Suitability class (SC) SI = 0 Unsuitable 0 < SI ≤ 0.2 Very Poor 0.2 < SI ≤ 0.4 Poor 0.4 < SI ≤ 0.6 Medium 0.6 < SI ≤ 0.8 Good SI > 0.8 Very Good Table 3. Conversion of suitability values to suitability classes. As a preeminent agricultural country in the MENA region13, Iran has long been pursuing an ambitious plan to achieve food self- sufciency. Iran’s self- sufciency program for wheat started in 199014, but the low rate of production increase (Supplementary Fig. S1) has never sustainably alleviated the need for grain imports. Currently, Iran’s agriculture supplies about 90% of the domestic food demands but at the cost of consuming 92% of the available freshwater15–19. In rough terms, the net value of agricultural import (i.e. ~$5B) is equal to 14% of Iran’s current oil export gross revenue20. Located in a dry climatic zone, Iran is currently experiencing unprecedented water shortage problems which adversely, and in some cases irreversibly, afect the country’s economy, ecosystem func- tions, and lives of many people21, 22. Te mean annual precipitation is below 250 mm in about 70% of the country and only 3% of Iran, i.e. 4.7 million ha, receives above 500 mm yr−1 precipitation (Supplementary Fig. S2). Te geographical distribution of Iran’s croplands (Supplementary Fig. S3) shows that the majority of Iran’s cropping activities take place in the west, northwest, and northern parts of the country where annual precipitation exceeds 250 mm (Supplementary Fig. S2). However, irrigated cropping is practiced in regions with precipitations as low as 200 mm year−1, or even below 100 mm year−1. To support agriculture, irrigated farming has been implemented unbridled, which has devastated the water scarcity problem22, 23. Te increase in agricultural production has never been able to keep pace with raising demands propelled by a drastic population growth over the past few decades, leading to a negative net international trade of Iran in the agriculture sector with a declining trend in the near past (Supplementary Fig. S1). Although justifed on geopolitical merits, Iran’s self-sufciency agenda has remained an issue of controversy for both agro-ecological and economic reasons. Natural potentials and constraints for crop production need to be assessed to ensure both suitability and productivity of agricultural systems. However, the extents to which the land and water resources of Iran can meet the nation’s future food demand and simultaneously maintain environmental integrity is not well understood. With recent advancement in GIS technology and availability of geospatial soil and climate data, land suitability analysis now can be conducted to gain insight into the capability of land for agricultural activities at both regional24, 25 and global scales26, 27. Land evaluation in Iran has been conducted only at local, small scales28 and based on the specifc requirements of a few number of crops such wheat29, rice30 and faba bean31. However, there is no large scale, country-wide analysis quantifying the suitability of Iran’s land for agricultural use. Herein, we systematically evaluated the capacity of Iran’s land for agriculture based on the soil properties, topography, and climate conditions that are widely known for their relevance with agricultural suitability. Our main objectives were to: (i) quantify and map the suitability of Iran’s land resources for cropping, and (ii) examine if further increase in production can be achieved through agriculture expansion and/or the redistribution of croplands without expansion. Te analyses were carried out using a large number of geospatial datasets at very high spatial resolutions of 850 m (for soil properties and climate) and 28 m (for topography). Our results will be useful for estimating Iran’s future food production capacity and hence have profound implications for the country’s food self-sufciency program and international agricultural trade. Although the focus of this study is Iran, our approach is transferrable to other countries, especially to those in the MENA region that are facing similar challenges: providing domestic food to a rapidly growing population on a thirsty land.

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