بررسی اثرات خشکسالی بر روی عملکرد گندم آبی و دیم در منطقه بجنورد

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی آب، دانشکده کشاورزی، دانشگاه جیرفت، جیرفت، ایران

2 دانشجوی کارشناسی مهندسی آب، دانشکده کشاورزی، دانشگاه جیرفت، جیرفت، ایران

چکیده

خشکسالی پدیده‌ای آرام و خزنده که خسارات زیادی و جبران­ ناپذیری به طبیعت وارد می ­کند و تمام اقلیم‌ها را تحت تأثیر قرار می­ دهد. یکی از پیامدهای اقلیمی مهم برای زراعت، خشکسالی ­های پیاپی است که هر چند سال اتفاق می ­افتد و باعث کاهش عملکرد تولید به‌ویژه در شرایط کشاورزی دیم می شود. لذا این تحقیق باهدف پایش خشکسالی­ ها و تأثیر خشکسالی کشاورزی بر روی محصول استراتژیک گندم تحت شرایط کشت دیم و آبی در منطقه بجنورد انجام شد. در این راستا برای محاسبه شاخص­ های خشکسالی بارش استاندارد شده (SPI)، شاخص درصد نرمال (PN) و شاخص نمره Z (ZSI) از آمار و اطلاعات بارندگی ایستگاه هواشناسی بجنورد طی دوره زمانی 1384 تا 1398 استفاده شد. همچنین جهت ارتباط خشکسالی­ ها با محصولات کشاورزی از آمار و اطلاعات میزان سطح زیر کشت، میزان تولید و عملکرد محصول گندم دیم و آبی طی دوره آماری 1362 تا 1398 استفاده شد. نتایج همبستگی پیرسون بین شاخص­های خشکسالی با سطح زیر کشت، میزان تولید و عملکرد محصول گندم دیم و آبی نشان داد که کمترین همبستگی مربوط به شاخص ZSI با عملکرد آبی به مقدار r=0/23 و بیشترین همبستگی مربوط به میزان تولید دیم با شاخص PN به مقدار r=0/73 می­باشد. همچنین تغییرات زمانی سطح زیر کشت آبی و دیم گندم در منطقه بجنورد نشان می ­دهد، با گذشت زمان از سطح زیر کشت محصول گندم دیم به‌شدت کاسته شده است (شیب‌خط روند معادله منفی می­باشد) که یکی از علت‌های اصلی آن کاهش ریزش­ های جوی و خشکسالی در منطقه می ­باشد که خسارات جبران‌ناپذیری بر کشاورزان وارد کرده است. نتایج تغییرات شاخص SPI روی سطح برداشت از اراضی کشت دیم و آبی نشان داد که در زمان ترسالی، برداشت محصول از اراضی زیر کشت دیم و آبی افزایش‌یافته است و در زمان خشکسالی میزان برداشت محصول کاهش‌یافته است؛ اما در مورد کشت آبی در سال­هایی که خشکسالی رخ‌داده است، کاهش سطح برداشت آبی از شدت کمتری برخوردار بوده است و دلیل آن می­تواند استفاده از روش­ های دیگر تأمین آب برای کشت ازجمله حفر چاه ­های غیرمجاز و عمیق‌تر کردن چاه ­های کشاورزی ­باشد.

کلیدواژه‌ها


عنوان مقاله [English]

Evaluation of drought impacts on irrigated and rainfed wheat yields in Bojnourd region

نویسندگان [English]

  • Mohammad Naderianfar 1
  • Elham Heydari Gharae 2
1 Department of Water Engineering, Faculty of Agriculture, University of Jiroft, Jiroft, Iran
2 B.Sc. Student, Department of Water Engineering, Faculty of Agriculture, University of Jiroft, Jiroft, Iran
چکیده [English]

Drought is a slow-onset and creeping phenomenon that imposes many irreparable natural hazards and affects all climates. One of the important climatic consequences for agriculture is consecutive droughts that occur every few years and reduce the production yield, in particular under rainfed farming conditions. Therefore, this study was conducted to monitor droughts and the impact of agricultural drought on the strategic wheat crop under rainfed and irrigated cultivation conditions in the Bojnourd region. In this regard, to calculate the standardized drought indices i.e. Standardized Precipitation Index (SPI), Percent of Normal Index (PN), and Z-score Index (ZSI), rainfall statistics, and information of Bojnourd meteorological station during the period 2005 to 2019 were used. Likewise, to relate droughts to agricultural products, statistics and information on the area under cultivation, production, and yield of rainfed and irrigated wheat were used during the statistical period of 1983 to 2019. The results of pearson correlation between drought indices and area under cultivation, production, and crop yield of rainfed and irrigated wheat indicated that the lowest (r = 0.23) and the highest (r = 0.73) correlation levels belonged to the ZSI index with irrigated yield and rainfed production with the PN index, respectively. Temporal changes in the area under cultivation of irrigated and rainfed wheat in Bojnourd region showed that the area under irrigated wheat crop cultivation decreased sharply over time (a negative slope for the trend line of the equation), which is mainly due to the decline in precipitations and droughts in the region causing irreparable damage to farmers. The results of variations in the SPI index on the harvest level from rainfed and irrigated fields indicated that the harvest level from rainfed and irrigated fields increased during the wet year while it decreased during droughts. However for irrigated cultivation, the reduction of irrigated crop yield was less severe over drought years probably due to the use of other methods of water supply for cultivation, including drilling illegal wells and deepening agricultural wells.

کلیدواژه‌ها [English]

  • Agricultural drought
  • Rainfed and irrigated cultivation
  • SPI Index
  • Wheat yield
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