چکیده:
برای استفادة درست از منابع آب و جلوگیری از تخریب خاک، باید مناسبترین سامانههای آبیاری را بهکار برد. هدف از انجام پژوهش حاضر، ارزیابی تناسب اراضی برمبنای ویژگیهای خاک برای سامانههای آبیاری سطحی و قطرهای در 46000 هکتار از اراضی دشت سیستان است. بهمنظور دستیابی به این هدف، 600 خاکرخ با فواصل تقریبی 700 تا 800 متر حفر و ویژگیهای فیزیکی و شیمیایی تمامی افقها تعیین شد. ارزیابی تناسب برای روشهای مختلف آبیاری برمبنای ویژگیهای خاک و توپوگرافی با استفاده از روش پارامتریک انجام شد. پس از تعیین کلاس و زیرکلاس تناسب سرزمین برای خاکرخهای مطالعهشده، با استفاده از روش وزندهی معکوس فاصله، نقشههای پیوستة زیرکلاسهای تناسب برای هر دو روش آبیاری در شهرستانهای مختلف تهیه شد. نتایج نشان داد که در تمامی مناطق، شرایط برای آبیاری قطرهای بهمراتب بهتر از آبیاری سطحی است. هرچند در بسیاری از مناطق، برای آبیاری قطرهای نیز، محدودیتهایی وجود دارد و استفادة مناسب و کارآمد از این نوع سامانه به رفع محدودیتها در این مناطق بستگی دارد. در تمامی شهرستانها، مهمترین محدودیت برای روشهای آبیاری بررسیشده، محدودیت شوری ـ قلیائیت و ویژگیهای فیزیکی خاک (بافت شنی، رسی و رسی ـ سیلتی) است. در تمامی مناطق، بافتهای رسی ـ سیلتی و لومی ـ سیلتی مهمترین کلاسهای بافتی محدودکننده بودند. با توجه به اینکه تغییر ویژگیهای فیزیکی بهراحتی امکانپذیر نیست، عملیات اصلاح خاکها ازنظر مقادیر شوری ـ قلیائیت به رفع محدودیتها یا کاهش آنها کمک زیادی میکند.
AbstractFor the proper use of water resources and prevention of soil degradation, it is necessary to select the best irrigation system. The aim of this study was to map the land suitability evaluation for different irrigation methods (surface and drip) in 46000 ha of Sistan plain including Hirmand, Hamon, Nimroz, Zahak, and Zabol counties. For this purpose, 600 pedons with an approximate distance of 700 to 800 m were excavated, described, and sampled. In this study, land suitability evaluation for different irrigation methods based on soil properties and topography was done using the parametric method. Then, land suitability maps for surface and drip irrigation methods were prepared using the Inverse Distance Weighting (IDW) method. The results showed that in the studied area, the conditions for drip irrigation are better than the surface irrigation method. However, in many studied areas, there are restrictions for drip irrigation, and for proper and efficient use of this irrigation system, the restrictions must be removed. Moreover, the results confirmed that in all studied areas the most important limitations are salinity/alkalinity and limitations due to physical soil properties. The silty clay and silty loam textural were the most limitation classes. Due to the fact that changing the physical properties is not easily possible, it seems that soil remediation based on salinity and alkalinity can help to remove or reduce the limitations. IntroductionFood security and stability in the world greatly depend on the management of natural resources. Moreover, farm production should be increased using these limited resources for feeding the growing global population. The scarcity of water in arid and semiarid regions such as Iran is a restrictive element for the agricultural sector. Therefore, there is an urgent need to develop initiatives to save water in this particular sector. For proper use of water resources and prevention of soil degradation, it is necessary to select the best irrigation system. In this regard, the aim of this study was to map the land suitability evaluation for different irrigation methods (surface and drip) in 46000 ha of Sistan plain including Hirmand, Hamon, Nimroz, Zahak, and Zabol counties. MethodologyThe present study was conducted in an area of about 46000 ha in the Sistan plain, northeast of Sistan and Baluchestan Province, Iran. The Sistan plain is located in Hirmand, Hamon, Nimroz, Zahak and Zabol counties. In this study, 600 pedons with an approximate distance of 700 to 800 m were excavated. All the pedons were described according to the field book for describing and sampling soils (Schoeneberger, Wysocki, & Benham, 2012). Then, soil samples were taken from different genetic horizons. Soil samples were air-dried, grounded, and passed through a 2-mm sieve. Then, particle size distribution, pH, Electrical conductivity (EC), calcium carbonate equivalent (CCE), the content of organic carbon, soluble Ca, Mg, Na, and K were determined. In this study, land suitability evaluation for different irrigation methods based on soil properties and topography was done using the parametric method. The capability index for irrigation was determined based on the rating of soil properties. Then, the suitability classes were defined according to the value of the capability index. After that, land suitability maps for surface and drip irrigation methods were prepared using the Inverse Distance Weighting (IDW) method. DiscussionThe results show that Hirmand County with 916 ha has the highest and Hamoon County with 226 ha has the lowest land area with S1 suitability class for surface irrigation. In Hamoon County, in relation to the ability to use surface irrigation, the majority of the studied lands (approximately 4492 ha) have S2ns class. Zahak County with 929 ha has the highest and Hamoon County with 214 ha has the lowest level of lands with S1 suitability class for drip irrigation. Based on the values of overall accuracy and kappa index, it can be stated that for all counties and both irrigation methods, the predictions were accurate. The overall accuracy of 80% and the kappa index of 0.7 indicate the high accuracy of the predicted maps. ConclusionThe results show that in the studied area, the conditions for drip irrigation are better than the surface irrigation method. However, in many studied areas, there are restrictions for drip irrigation, and for proper and efficient use of this irrigation system, the restrictions must be removed. Moreover, results confirm that, in all studied areas, the most important limitations are salinity/alkalinity and limitations due to physical soil properties. The silty clay and silty loam textural are the most limiting classes. As changing the physical properties is not easily possible, it seems that soil remediation based on salinity and alkalinity can help to remove or reduce the limitations. Keywords: Suitability Index, Pedon, Irrigation System. References- Albaji, M., Nasab, B., & Naseri, A. A. (2010). Comparison of different irrigation methods based on the parametric evaluation approach in the plain West of Shush, Iran. Journal of Irrigation and Drainage, 59(1), 547-558.- Albaji, M., Eslamian, S., Naseri, A. A., & Eslamian, F. (2020). Handbook of irrigation system selection for semi-arid regions. CRC Press, Taylor and Francis Group.- Barberis, A., & Minelli, S. (2005). Land evaluation in Shouyang County, Shanxi Province, China. The 25th Professional Master Course. IAO: Florence, Italy.- Bienvenue, J. S., Ngardeta, M., & Mamadou, K. (2003). Land evaluation in the Province of Thies Senegal. The 23rd Professional Master Course. IAO: Florence, Italy.- Braester, C. (1983). Moisture variation at the soil surface and the advance of the wetting front during infiltration at constant flux. Journal of Water Resource Research, 9(1), 687-694.- Cindy, S. K., & Hunt, J. R. (1996). Prediction of wetting front movement during one-dimensional infiltration into soils. Journal of Water Resource Research, 32(1), 55–64.- Congalton, R. (1991). A review of assessing the accuracy of classification of remotely sensed data. Journal of Remote Sensing Environmental, 37(1), 35–46. - Dengiz, O. (2006). Comparison of different irrigation methods based on the parametric evaluation approach. Turkish Journal of Agriculture and Forestry, 30(1), 21-29.- FAO. (2017). Water for sustainable food and agriculture. A report produced for the G20 presidency of Germany. Roma: Food and Agriculture Organization of the United Nations.- Jolaini, M., & Mehrabadi, H. R. (2012). Investigation the effect of surface and subsurface drip irrigation methods and irrigation interval on yield quality and quantity of cotton. Journal of Water and Soil, 26(3), 736-742.- Schoeneberger, P. J., Wysocki, D. A., & Benham, E. C. (2012). Field book for describing and sampling soils. Natural Resources Conservation Service. National Soil Survey Center.- Sedigh Kia, M., Nateghi, M. B., Kaviayni, S., & Naghipour, N. (2015). Evaluation and zoning of irrigation methods on Etka orginiziation lands in Dorud, using analytical hierarchy process. Journal of Water Research in Agriculture, 28(4), 749-758.- Soil Survey Staff. (1996). Soil survey laboratory methods manual. Natural Resources Conservation Service (NRCS).- Sys, C., Van Ranst, E., & Debaveye, J. (1991). Land evaluation, principles in land evaluation and crop production calculations. Agricultural Publications.
خلاصه ماشینی:
مقاله پژوهشي ارزيابي تناسب اراضي براي روش هاي آبياري سطحي و قطره اي در دشت سيستان نمونۀ پژوهش : شهرستان هاي استان سيستان و بلوچستان زهره مصلح *، استاديار موسسه تحقيقات خاک و آب ، سازمان تحقيقات ، آموزش و ترويج کشاورزي، کرج ، ايران mosleh.
Bienvenue et al تناسـب سـرزمين براي روش هاي آبياري سطحي و قطره اي را در تيس و سنگال با استفاده از روش پارامتريک ارزيابي کردند و دريافتنـد که زهکشي خاک و بافت شني، محدودکننده ترين عوامل در اين منطقه اند.
جدول ١- درجات کلاس هاي بافت خاک براي روش هاي آبياري سطحي و قطره اي Table 1- Rating of textural classes for surface and drip irrigation methods )به تصویر صفحه رجوع شود) **: Gravels with 2mm to 2.
جدول ٨- درجات زهکشي خاک براي روش هاي آبياري سطحي و قطره اي )به تصویر صفحه رجوع شود) جدول ٩- درجات شيب براي روش هاي مختلف آبياري )به تصویر صفحه رجوع شود) پس از تعيين درجۀ تناسب هريک از عوامل يادشده ، براساس رابطۀ زير، شاخص تناسـب اراضـي آبيـاري ( Land Suitability Index for Irrigation) محاسبه شد: )به تصویر صفحه رجوع شود) در اين رابطه ، LSI= شاخص تناسب اراضي براي آبياري، A= درجۀ بافت خاک، B= درجۀ عمق خـاک، C= درجـۀ کربنات کلسيم معادل ، D= درجۀ گچ ، E= درجۀ شـوري ــ قليائيـت ، F= درجـۀ زهکشـي و G درجـۀ شـيب اسـت .
)به تصویر صفحه رجوع شود) شکل ٦- نقشۀ زيرکلاس هاي تناسب آبياري سطحي (الف ) و آبياري قطره اي (ب ) در شهرستان زابل Figure 6- Map of suitability subclasses for surface (A) and drip (B) irrigation methods in Zabol County جدول ١٣ نتايج اعتبارسنجي پيش بيني زيرکلاس هاي تناسب سـرزمين بـراي آبيـاري سـطحي و قطـره اي را نشـان ميدهد.