نوع مقاله : فنی ترویجی

نویسنده

استاد گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایران

چکیده

فسفر یکی از عناصر غذایی پرمصرف مورد نیاز گیاهان است و کمبود آن در بسیاری از خاک‌های کشاورزی جهان وجود دارد. برای درمان کمبود فسفر از کودهای فسفر استفاده می‌شود که کارایی مصرف آن‌ها کم بوده و پدیده غنی‌شدن آب‌ها و آلودگی محیط‌زیست را نیز به‌طور گسترده ایجاد کرده است. ازطرف‌دیگر، کودهای فسفر از ذخایر محدود و تجدیدناپذیر سنگ فسفات تولید می‌شوند که با گذشت زمان مقدار آن کم شده و قیمت آن گران‌تر می‌شود. این در حالی است که نیاز به مصرف کودهای فسفر برای تأمین غذای مورد نیاز جمعیت در حال رشد جهان زیاد می‌شود. بنابراین، مدیریت کودهای فسفر یک عامل کلیدی در تولید محصولات کشاورزی است. برای بهبود کارایی مصرف فسفر و رشد گیاهان و کاهش مخاطرات محیط‌زیست، استفاده از کودهای کندرها و با رهایش کنترل‌شده فسفر مورد توجه پژوهشگران قرار گرفته است. کود کندرها یا با رهایش کنترل‌شده به کودی گفته می‌شود که سرعت حل‌شدن آن در آب کم‌تر از کودهای محلول در آب رایج بوده و مدت طولانی‌تری عناصر غذایی را به ریشه گیاهان عرضه می‌کند. برخلاف کود کندرها، کود با رهایش کنترل‌شده طوری ساخته می‌شود که سرعت، مدت و الگوی رهایش عنصر غذایی خوب کنترل شده باشد. برای تهیه کودهای کندرها یا با رهایش کنترل‌شده از چندین روش استفاده می‌شود: (1) استفاده از مواد پوشش‌دهنده: این مواد به چند گروه تقسیم می‌شوند: 1- پلیمرها (شامل پلیمرهای زیست‌تخریب‌پذیر مانند کیتوسان، پلیمرهای ابرجاذب آب، کوپلیمرهای پلی‌وینیلیدن کلراید، پلی‌اولفین‌ها، پلی‌اورتان‌ها، رزین‌های اوره-فرمالدئید، پلی‌استرها و رزین‌های آلکید)، 2- گوگرد، 3- گوگرد-پلیمر، 4- اسیدهای آلی، 5- روغن پارافین، 6- رس‌ها، 7- خاکستر بادی؛ (2) تهیه کودهای کندرها از موادی با حل‌پذیری کم یا سرعت معدنی‌شدن کم، (3) تبدیل سنگ فسفات به کود کندرها با روش‌های مختلف مانند اسیدی‌کردن جزئی و استفاده از ریزجانداران حل‌کننده فسفات، (4) تولید کودهای کندرهای فسفر با استفاده از فناوری نانو، (5) تولید کودهای کندرهای فسفر از هیدروکسیدهای دوگانه لایه‌ای، بیوچار و هیدروچار بارگذاری شده با فسفات، (6) تهیه کود کندرهای فسفر از خاکستر بادی. در این مقاله روش‌های تهیه کودهای کندرهای فسفر و اثرهای آن‌ها بر کارایی مصرف فسفر و رشد گیاهان مختلف شرح داده می‌شود. به‌طور کلی، با مصرف کودهای کندرها یا با رهایش کنترل‌شده فسفر در خاک‌های کشاورزی، کارایی مصرف فسفر و رشد گیاهان بهبود می‌یابد.

کلیدواژه‌ها

عنوان مقاله [English]

Sustained/Controlled-Release Phosphorus Fertilizers: An Option for Enhancing Phosphorus Use Efficiency in Agriculture and Abating the Environmental Hazards

نویسنده [English]

  • Nosratollah Najafi

Professor of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.

چکیده [English]

Phosphorus (P) is a macronutrient of high consumption required by plants. Most agricultural soils around the world are poor in phosphorus and P fertilizers are used as a remedy. Not only are the fertilizers low in use efficiency but their application has also exacerbated the eutrophication of water bodies and the associated environmental pollution. This is while P fertilizers are extracted from the finite and non-renewable phosphate rock reserves, causing their rising prices over time as more P fertilizers will be needed to produce more food for the growing global population. P fertilizer management is, therefore, a key parameter in agricultural production. This is why a lot of attention has been recently paid to the application of sustained/controlled-release P fertilizers (SRF/CRF) in order to improve upon P use efficiency and plant growth at reduced environmental costs. The designation SRF/CRF is due to the lower water solubility of such fertilizers compared to conventional ones so that nutrients are supplied to plant roots over longer periods of time. Unlike SRFs, CRFs are characterized by well-controlled nutrient release rate, pattern, and duration. The methods used to manufacture P SRF include: 1) Coating the fertilizer with such materials as: a) polymers (including biodegradable polymers like chitosan, water-superabsorbent polymers, PVDC copolymers, polyolefins, polyurethanes, urea-formaldehyde resins, polyesters, and alkyd resins), b) sulfur, c) sulfur-polymers, d) organic acids, e) paraffin, f) clays, and g) fly ash; 2) Preparing SRFs from materials with a low solubility or a low mineralization rate; 3) Conversion of phosphate rock into P SRF using such different methods as partial acidification and phosphate solubilizing microorganisms; 4) Manufacturing P SRFs via nanotechnology-based techniques; 5) Producing P SRFs using phosphate-loaded layered double hydroxides, biochar, and hydrsochar; and 6) Using fly ash to manufacture SRF. The present article examines these methods and the effects of each on P use efficiency and the growth of different plants. It is generally concluded that P SRFs or CRFs improve P use efficiency and plant growth.

کلیدواژه‌ها [English]

  • Nanotechnology
  • Phosphorus
  • Slow-release fertilizer
  • Use efficiency
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