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مهندسی زراعی - سال چهل و یکم شماره 4 (زمستان 1397)

نشریه مهندسی زراعی
سال چهل و یکم شماره 4 (زمستان 1397)

  • تاریخ انتشار: 1397/12/01
  • تعداد عناوین: 9
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  • حمید کلیشادی، محمدرضا مصدقی*، شمس الله ایوبی، حسین اسدی صفحات 1-15
    پایداری خاکدانه ها یکی از عوامل مهم اثرگذار بر فرسایش خاک است. هدف از انجام این پژوهش مقایسه روش های مختلف برآورد پایداری خاکدانه ها، شامل اندازه گیری پاشمان، الک تر و مقاومت برشی اندازه گیری شده با فروسنج مخروطی افتان برای برآورد فرسایش پاشمان است. برای این منظور، 28 نمونه خاک با ویژگی های اولیه متفاوت از نظر بافت، آهک و ماده آلی از خاک های سطحی استآن های اصفهان و چهارمحال بختیاری جمع آوری شد. میزان پاشمان (S) با دستگاه شبیه ساز باران، مقاومت برشی (τ) با فروسنج مخروطی افتان و میانگین وزنی قطر خاکدانه ها (MWD) و میانگین هندسی قطر خاکدانه ها (GMD) با استفاده از الک تر اندازه گیری شدند. نتایج همبستگی بین روش های مختلف نشان داد میزان پاشمان با τ و GMD همبستگی منفی و معنی دار و τ با GMD و MWD همبستگی مثبت و معنی دار داشت. نتایج نشان داد که S عمدتا به توزیع اندازه ذرات، MWD و GMD به کربن آلی، و τ هم به توزیع اندازه ذرات و هم به کربن آلی خاک وابسته است. برای ارزیابی کارآیی روش ها در خاک های متفاوت، خاک های مورد مطالعه با استفاده از روش K-means در محیط نرم افزار MATLAB بر اساس ویژگی های اولیه خوشه بندی شدند. مقایسه میانگین بین خوشه ها با استفاده از آزمون حداقل تفاوت معنی دار (LSD) در قالب طرح کاملا تصادفی انجام شد. نتایج مقایسه میانگین نشان داد هر سه روش، روند تغییرات پایداری خاکدانه در گروه های مختلف را به طور مشابه برآورد می کنند؛ بنابراین روش های ذکرشده به جای یکدیگر قابل استفاده هستند و فروسنج مخروطی افتان را می توان به عنوان یک روش درجا برای اندازه گیری پایداری خاکدانه در برابر فرسایش پاشمانی معرفی کرد.
    کلیدواژگان: پایداری خاکدانه، فروسنج مخروطی افتان، فرسایش پاشمانی، شبیه ساز باران چندمتغیره، الک تر
  • سمیه سفیدگر شاهکلایی، مجتبی بارانی مطلق*، فرهاد خرمالی، اسماعیل دردی پور صفحات 15-29
    آلودگی منابع آب و خاک به فلزات سنگین، از چالش های مهم عصر کنونی است؛ به همین دلیل، آلودگی زدایی چنین خاک هایی، پیش نیاز هرگونه بهره برداری بهینه از این منابع است. یکی از روش های مقرون به صرفه برای پیش گیری از انتشار فلزات سنگین در منابع آب و خاک، تثبیت و جامدسازی آن هاست. طی این فرایند، فلزات سنگین در خاک های آلوده با اصلاح کننده هایی همچون مواد آلی و  معدنی واکنش داده و با تشکیل موادی کم محلول یا نامحلول در محیط، به صورتی پایدار باقی می مانند. در این پژوهش، به منظور بررسی اثر مواد اصلاحی آلی (بیوچار تهیه شده در دمای 640 و زمان 30 دقیقه از کاه و کلش برنج و بیوچار تهیه شده در دمای 420 و زمان 2 ساعت از کاه و کلش برنج) و معدنی (پومیس، لیکا، زئولیت و بنتونیت) در سه سطح صفر، 1 و 5 درصد وزنی بر عدم تحرک و تثبیت دو فلز کادمیوم و سرب در خاک های آلوده، آزمایشی در قالب طرح کاملا تصادفی با سه تکرار  انجام گرفت. نتایج حاصل از این پژوهش نشان داد که افزودن مواد اصلاحی به خاک، موجب کاهش غلظت کادمیوم و سرب عصاره گیری شده با DTPA و EDTA شد. بیشترین کاهش غلظت سرب عصاره گیری شده با DTPA و EDTA (بخش محلول یا زیست فراهمی) در تیمار سطح 5٪ بیوچار 640 مشاهده شدکه در مقایسه با شاهد، به ترتیب کاهشی معادل 68 و 2/41 درصد داشتند؛ همچنین بیشترین کاهش غلظت کادمیوم عصاره گیری شده با DTPA و EDTA به ترتیب مربوط به تیمارهای سطح 5٪ پومیس و زئولیت  بود که به ترتیب 39 و 8/28 درصد نسبت به شاهد کمتر بودند. بیشترین کاهش غلظت سرب و کادمیوم در بخش تبادلی  در سطح 5٪ بیوچار 640 مشاهده شد که در مقایسه با شاهد، به ترتیب کاهشی معادل 96/54 و 41 درصد  داشتند. کاربرد اصلاح کننده ها، اثری معنی دار بر مقدار کل سرب و کادمیوم خاک نداشتند. بنابراین، تکنیک حاضر، می تواند به طور موثری، زیست فراهمی سرب و کادمیوم را در خاک کاهش دهد که این مساله می تواند در اصلاح خاک استفاده شود.
    کلیدواژگان: اصلاح کننده، زیست فراهمی، شکل های شیمیایی، سرب، کادمیوم
  • منصوره خالقی، اعظم جعفری*، محمد هادی فرپور صفحات 31-48
    شناسایی رقومی خاک، برای استفاده مفید و موثر از خاک و تصمیم گیری های مدیریتی مهم است. این پژوهش با هدف تهیه نقشه رقومی گروه بزرگ خاک با روش رگرسیون لاجیستیک چند جمله ای با استفاده از دو مجموعه از متغیر های کمکی، شامل: مجموعه (1) متغیر های مشتق شده از مدل رقومی ارتفاع، شاخص های سنجش از دور، سطوح ژئومورفیک تفکیک شده و نقشه زمین شناسی منطقه ی مورد پژوهش، و مجموعه (2) متغیر های مشتق شده از مدل رقومی ارتفاع، شاخص های سنجش از دور، سطوح ژئومورفیک تفکیک شده، نقشه زمین شناسی و واحد های خاک شناسایی شده (نقشه قدیمی خاک)، در بخشی از اراضی منطقه ی فاریاب کرمان، طراحی شد. به منظور دست یابی به این هدف، نقشه ژئومورفولوژی بر مبنای توپوگرافی، مواد مادری و تفسیر تصاویر ماهواره ای تهیه شد. از طرح نمونه برداری لاتین هایپر کیوب در منطقه مورد پژوهش به مساحت 14 هزار هکتار، برای تعیین نقاط نمونه برداری استفاده شد و 70 خاکرخ حفر و تشریح شد. نتایج این پژوهش نشان داد شاخص موقعیت توپوگرافی، بیشترین تاثیر را در پیش بینی گروه های بزرگ خاک دارد. نتایج ارزیابی دقت مدل رگرسیون لاجیستیک چند جمله ای، نشان داد که با به کارگیری نقشه قدیمی خاک در مدل سازی، شاخص های اعتبار سنجی مدل، از جمله خلوصنقشه و شاخص کاپا به ترتیب از 47/0 و 16/0 به 63/0 و 43/0 افزایش یافتند. به طور کلی نتایج نشان داد که دقت روش  نقشه برداری رقومی با بکارگیری نقشه قدیمی خاک، می تواند ارتقاء پیدا کند و کاربرد نقشه های تولید شده را افزایش دهد؛ همچنین قابلیت استفاده از این نقشه ها را برای شاخه های علمی مختلف امکان پذیر کند.
    کلیدواژگان: رگرسیون لاجیستیک چند جمله ای، گروه بزرگ خاک، متغیر های کمکی، نقشه قدیمی خاک
  • سمیرا علوانی، سعید حجتی*، احمد لندی صفحات 49-65
    تا کنون پژوهش های اندکی در رابطه با بررسی توانایی نانوذرات پالیگورسکیت در کاهش آلودگی فلزات سنگین از محیط زیست انجام شده است. این پژوهش با هدف بررسی توانایی کانی پالیگورسکیت در اندازه های نانو و میکرو در حذف رقابتی سرب و مس از محلول های آبی صورت گرفته است.آزمایش های سینتیکی در 11 زمان تماس مختلف با استفاده از محلول هایی که حاوی 150 میلی گرم بر لیتر از عناصر سرب و مس بودند، انجام شده است. کانی پالیگورسکیت  به ترتیب با استفاده از آسیاب برقی و آسیاب گلوله ای سیاره ای در دو اندازه کوچکتر از 1/0 میلی متر و کوچکتر از 100 نانومتر تهیه و خصوصیات فیزیکی و شیمیایی کانی، شامل ظرفیت تبادل کاتیونی (از روش اشباع سازی با استات سدیم)، سطح ویژه (روش BET) و تجزیه عنصری آن به روش XRF اندازه گیری شده است. تعیین همدماهای جذب عناصر در قالب آزمایشات پیمانه ای و 6 غلظت تعادلی انجام شد.نتایج این پژوهش نشان می دهد که با افزایش زمان تماس و کاهش اندازه ذرات از میکرو به نانو جذب عناصر سنگین سرب و مس افزایش یافته است؛ همچنین در ارزیابی سه مدل سینتیکی درجه اول، درجه دوم کاذب و پخشیدگی درون ذره ای جهت توصیف فرآیند جذب سرب و مس توسط کانی پالیگورسکیت به نظر می رسد مدل درجه دوم در توصیف فرآیند جذب سرب و مس توسط هر دو اندازه ذرات کانی تخمین های قابل قبول تری را ارائه می دهد. همچنین نتایج مدل لانگمویر برازش بهتری نسبت به مدل فروندلیچ نشان می دهد؛ بر این اساس، به نظر می رسد ظرفیت جذب سرب از محلول های آبی توسط میکرو و نانوذرات کانی پالیگورسکیت نسبت به مس بیشتر است.
    کلیدواژگان: نانوذرات، پالیگورسکیت، سینتیک، سرب، مس
  • معصومه نجفی نیا، فرهاد خرمالی*، فرشاد کیانی، مجتبی بارانی مطلق صفحات 67-82
    وجود تناوبی از خاک های قدیمی در رسوبات لسی شمال ایران، اشاره به دوران سرد و خشک در زمان رسوب گذاری لس و دوران گرم و مرطوب در زمان تشکیل خاک های قدیمی دارد. از این رو، این پژوهش با هدف پژوهش میکرومورفولوژیک خاک های لسی اوایل پلیستوسن و مقایسه آن با لس های مدرن در مناطق آق بند، یلی بدراق و قره آغاچ استان گلستان انجام شد. پس از مشاهدات مقدماتی و صحرایی و تعیین افق ها برای هر خاک رخ در منطقه، از هر یک از افق ها به مقدار کافی، نمونه خاک برای انجام آزمایش های فیزیکوشیمیایی و همچنین نمونه دست نخورده، به منظور پژوهش مقاطع نازک خاک جمع آوری شد. یکی از روش های مهم برای شناسایی و تفسیر لس های مدرن و خاک های قدیمی در راستای مطالعات اقلیم شناسی گذشته، بررسی میکرومورفولوژیکی خاک است. نتایج به دست آمده از مقاطع نازک خاک های پالئوسول و مدرن نشان می دهد که زمان و تغییرات آب و هوا، باعث تغییر در ویژگی های میکرومورفولوژی خاک (مانند نوع و تعداد حفرات، ریزساختمان خاک، بی فابریک و پدوفیچر و...) می شود. مشاهده های میکرومورفولوژیکی، شواهد مختلفی از وقوع فرآیندهای پدوژنیک را در این خاک ها نشان داد. بی فابریک غالب خاک ها به دلیل آبشویی آهک در افق های آرجیلیک، لکه ای و در افق های کلسیک، بلورین می باشد. از مهم ترین شاخص های خاک سازی، وجود پوشش های رسی دور حفرات در برخی از افق های خاک های قدیمی است که شواهدی از شرایط اقلیمی مرطوب تر برای آب شویی و انتقال رس است. تشکیل لس و خاک های قدیمی مورد پژوهش احتمالا به ترتیب مربوط به دوره های یخچالی و بین یخچالی با شرایط اقلیمی متفاوت بوده است.
    کلیدواژگان: لس- خاک قدیمی، آب و هوای گذشته، میکرومورفولوژی، گلستان
  • امیر رحیمی، بهنام دولتی*، سعید حیدرزاده صفحات 83-97
    به منظور بررسی تاثیر اسید هیومیک و عناصر کم مصرف بر برخی از ویژگی‎های کمی و کیفی چغندرقند رقم یونیورس آزمایشی به صورت فاکتوریل در قالب طرح پایه بلوک های کامل تصادفی با سه تکرار در اراضی تحقیقاتی کارخانه چغندرقند نقده اجرا گردید. تیمارهای آزمایشی شامل مقادیر مختلف اسید هیومیک شامل صفر، 200، 300، 400، 500 و 600 کیلوگرم در هکتار و محلول پاشی عناصر کم مصرف (آهن، روی، بر، منگنز و شاهد) به عنوان فاکتور دوم در نظر گرفته شد. صفات مورد مطالعه شامل درصد قند ناخالص، مقدار سدیم، پتاسیم و نیتروژن در غده، شاخص قلیایئت، ضریب استحصال قند، عملکرد ریشه، درصد قند خالص و قند ملاس بود. نتایج نشان داد که حداکثر درصد قند ناخالص (67/18 درصد)، خالص (30/16 درصد) و ضریب استحصال شکر (25/87 درصد) از تیمار مصرفی 500 کیلوگرم در هکتار اسید هیومیک با محلول پاشی بور (B) بدست آمد. کاربرد عناصر کم مصرف و اسید هیومیک سبب کاهش میزان قند ملاس و افزایش درصد پتاسیم ریشه چغندرقند گردید. افزایش مقادیر مصرفی اسید هیومیک به ترتیب سبب افزایش درصد عملکرد ریشه (08/ 29 درصد)، عملکرد قند ناخالص (75/32 درصد) و شاخص قلیایئت (39/29)، نسبت به تیمار شاهد شد. همچنین با افزایش مواد هومیکی مقادیر نیتروژن (58/27 درصد) و سدیم (89/24 درصد) در ریشه چغندرقند کاهش یافت. حداکثر عملکرد ریشه (96 /68 تن در هکتار) و عملکرد قند ناخالص (18/12 تن در هکتار) در تیمار با منگنز (Mn) به دست آمد. لذا جهت نیل به کشاورزی پایدار و افزایش عملکرد کمی و کیفی چغندرقندکاربرد اسید هومیک همراه با عناصرکم مصرف توصیه می شود.
    کلیدواژگان: درصد قند خالص، ضریب استحصال قند، عملکرد ریشه، کشاورزی پایدار، ملاس و اسید هیومیک
  • ثریا طاهری، عبدالمجید رونقی*، رضا قاسمی، صدیقه صفرزاده شیرازی صفحات 99-111
    هدف این پژوهش بررسی میزان ترشح اسیدهای آلی مالیک، سیتریک و استیک در شرایط کمبود روی، در دو رقم ذرت بود. آزمایش در قالب طرح فاکتوریل، کاملا تصادفی و در سه تکرار اجرا شد. بذرهای ذرت ارقام KSC704 و KSC703  پس از جوانه زنی به محیط کشت هیدروپونیک منتقل شده و تیمارهای روی در سه سطح صفر، 5/0و 1میکرو مولار به محیط کشت گیاهان اضافه شد. دو ماه پس از اعمال تیمارهای روی، ترشحات ریشه ای جمع آوری شدند و غلظت اسیدهای مالیک، استیک و سیتریک توسط دستگاه HPLC اندازه گیری شدند.از بین سه نوع اسید آلی اندازه گیری شده، اسید مالیک و پس از آن اسید سیتریک و اسید استیک، بیشترین میزان ترشحات را داشتند. با کاهش غلظت روی در ریشه و اندام هوایی، بر میزان ترشحات هر سه اسید آلی افزوده شد. بیشترین میزان اسید مالیک ترشح شده از ریشه (6/6 میلی گرم بر گرم وزن خشک ریشه) در رقم 703 و در تیمار بدون روی  و کمترین میزان ترشح مالیک اسید نیز(98/1میلی گرم بر گرم وزن خشک ریشه) در تیمار حد کفایت روی و در رقم 704 بود. بیشترین میزان ترشح اسید سیتریک و استیک نیز در هر دو رقم در سطح بدون روی بود. نتایج این پژوهش نشان دادکه با افزایش غلظت روی در محلول غذایی، وزن خشک اندام هوایی افزایش یافت. با افزایش غلظت روی در محلول غذایی از میزان نفوذپذیری غشا ریشه و ترشح اسیدهای آلی کاسته شد. در هر دو رقم، بیشترین نفوذپذیری غشا ریشه مربوط به سطح بدون روی بود که بیشترین میزان ترشح اسیدهای آلی از ریشه را داشتند. به طور کلی رقم 703 به دلیل ترشحات بیشتر اسیدهای آلی در شرایط کمبود روی، نسبت به رقم 704 در برابر کمبود روی مقاوم تر بوده و در این شرایط کاهش عملکرد کمتری نشان داد.
    کلیدواژگان: ذرت، اسید مالیک، اسید استیک، اسید سیتریک، کمبود روی
  • سروه مرادی، کمال نبی الهی*، سید محمد طاهر حسینی صفحات 113-129
    اثر جایگاه شیب و تخریب جنگل بر روی کیفیت خاک شناخته شده و مهم است. پایش تغییرات شاخص های کیفیت خاک، روشی ساده و معمول جهت ارزیابی کیفیت خاک است. در این پژوهش، اثر تخریب جنگل و جایگاه شیب بر روی شاخص کیفیت خاک وزنی تجمعی و نمرو در جنگل های مریوان در استان کردستان بررسی شد. تعداد 8 نیمرخ خاک در جایگاه های مختلف دو شیب تپه، تحت کاربری های جنگل و جنگل تخریب شده حفر و تشریح شدند. افزون بر این، در هر کاربری در هر موقعیت شیب، 3 نمونه خاک از عمق 20-0 سانتی متری برداشت شد. 15 ویژگی خاک اندازه گیری و به عنوان مجموعه کل داده ها استفاده شدند؛ سپس با استفاده از روش تجزیه مولفه اصلی هفت ویژگی خاک (کربن آلی، ظرفیت تبادل کاتیونی، رطوبت قابل دسترس، فسفر قابل دسترس، ازت کل، جرم مخصوص ظاهری و فرسایش پذیری خاک) به عنوان مجموعه حداقل داده ها انتخاب شدند. وزن و نمره هر ویژگی به ترتیب با استفاده از واریانس مشترک و توابع نمره دهی مشخص شدند و در نهایت شاخص کیفیت وزنی تجمعی خاک محاسبه شد. میانگین مقادیر شاخص های کیفیت خاک در جنگل تخریب شده به طور معنی داری، کمتر از کاربری جنگل بود؛ همچنین میانگین شاخص های کیفیت خاک در موقعیت شانه شیب به طور معنی داری کمتر از سایر موقعیت های شیب بود. ضریب همبستگی معنی دار قوی (98/0) بین شاخص های کیفیت وزنی تجمعی خاک محاسبه شده با استفاده از مجموعه کل داده ها و مجموعه حداقل داده ها به دست آمد.
    کلیدواژگان: کیفیت خاک، مجموعه حداقل داده، تجزیه به مولفه های اصلی، شیب تپه
  • علی عبدالهی، مهدی تقوی زاهد کلایی*، مجتبی نوروزی، عبدالامیر معزی صفحات 131-146
    در میان فناوری های نوین، فناوری نانو نقش مهمی در کشاورزی و تولید مواد غذایی دارد. در این راستا، آزمایشی به صورت طرح کامل تصادفی برای بررسی تاثیر نانو ذرات اکسید آهن عامل دار بر ویژگی های عملکردی و غلظت و جذب و روی گندم انجام شد. تیمارهای آزمایش، شامل نانو ذرات اکسید آهن عامل دار (هیدروکسیل OH، کربوکسیل COOH، آمین NH2) هر کدام در سه سطح (100، 200 و 300 میلی گرم بر کیلوگرم)، سولفات روی (ZnSO4) (در سطح 40 کیلوگرم در هکتار) و تیمار شاهد بودند. نتایج نشان داد که بیش ترین مقدار روی قابل دسترس خاک در تیمار نانو ذرات اکسید آهن کربوکسیل دار به مقدار 300 میلی گرم در کیلوگرم نسبت به تیمار شاهد به دست می آید.  بیش ترین مقدار عملکرد ریشه و ساقه در تیمار نانو ذرات اکسید آهن هیدروکسیل دار به مقدار 300 میلی گرم در کیلوگرم به دست آمد. نانو ذرات اکسید آهن کربوکسیل دار بیش ترین تاثیر را بر غلظت و جذب روی در گندم داشتند. بنابراین استفاده از نانو ذرات به مقدار مناسب می تواند موجب بهبود وضعیت عناصر غذایی خاک، محصولات و در نهایت انسان شود.
    کلیدواژگان: نانو ذرات، روی قابل دسترس، عملکرد، غلظت روی، گندم
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  • Hamid Kelishadi, Mohammad Reza Mosaddeghi *, Shamsollah Ayoubi, Hossein Asadi Pages 1-15
    Introduction
     Soil erosion is one of the major obstacles to sustainable development. A large part of Iran has an arid and semi-arid climate, without vegetation with suitable density or even completely without vegetation. Therefore, many parts of the country face high erosion and soil losses. Previous studies showed an increased trend of soil erosion in Iran. Because in situ measurement of soil erosion at the farm or watershed scale is expensive and time-consuming, estimation of soil erosion from easy and ready parameters can be useful. It is well-known that aggregate stability can affect soil erosion. There are many methods developed to measure soil aggregate stability, but there is no specific method that can be used for a wide range of soil types under different land uses. This study was done to compare different methods of aggregate stability determination (i.e., splash rate measurement, shear strength measured with fall-cone penetrometer and wet sieving).
    Materials and Methods
    Twenty-eight soil samples with different textures, equivalent calcium carbonate, and organic matter were collected from surface soil layers in Isfahan and Chaharmahal-va-Bakhtiari provinces. Particles size distribution of studied the soil was measured. Very coarse sand (VCS), coarse sand (CS), medium sand (MS), fine sand (FS) and very fine sand (VFS) were measured according to ASTM sieves. Also, four components of silt (0.035-0.05, 0.02-0.035, 0.01-0.02 and 0.002-0.01 mm) were measured according to Stock's law by the pipette method. Geometric mean diameter and geometric standard deviation of particles were calculated by Shirazi and Boeresma (1984) relations. Soil splash rate (S) was measured with rainfall simulator, near-saturated soil shear strength (τ) was determined using the fall-cone penetrometer, and mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates were measured by the wet sieving.
    Results and Discussio
    n The results of this study showed that the sand, silt and clay contents were, respectively, in the ranges of 1.5-51%, 34-73% and 11-35% in the studied soils. Most of the sand particles belonged to the FS and VFS (0.05-0.25 mm) fractions and most of the silt fraction was in the very fine silt (0.002-0.01 mm) fraction. The range of organic matter was 0.08 to 8.8% and calcium carbonate equivalent varied in the range between 10% and 63%. Generally, soil aggregate stability was low and splash erosion was high in the studied soils. The results showed that S showed significant correlations with sand, silt, and geometric mean diameter and geometric standard deviation calculated using all particle fractions, VCS, CS, MS, FS, fine silt and very fine silt. Soil shear strength (τ) had significant correlations with silt, very fine silt, geometric mean diameter and geometric standard deviation. The GMD and MWD had significant correlations with soil organic carbon. The results showed that S had significant and negative correlations with τ and GMD, and there were significant and positive correlations between τ with GMD and MWD. The S was mainly dependent on particle size distribution, while GMD and MWD mainly depended on soil organic carbon. However, both particle size distribution and soil organic carbon would affect τ. This finding might be justified by differences between mechanisms which are responsible for particles detachment. The energies induced by raindrop impact and slaking are the main forces and mechanisms responsible for detachment of particles in splash erosion and wet sieving tests, respectively while the cohesive forces between particles mainly govern soil strength in the fall-cone penetrometer test. The studied soils were clustered based on intrinsic soil properties (i.e., texture, CaCO3 and organic carbon) by using K-means method in MATLAB software, in order to evaluate the capability of different methods in different soil groups. The least significant difference (LSD) test was used in a completely randomized design for mean’ comparisons between the clusters. The mean comparison results showed that the three methods similarly predicted the variation of aggregate stability in different soil clusters. The results of clustering showed that the soil cluster with high organic matter, silt and clay contents and low sand content was more stable than other clusters.
    Conclusion
    Three methods similarly predicted the variation of aggregate stability in different soil groups; therefore, the methods might be used alternatively for aggregate stability determination. Fall-cone penetrometer can be introduced as an in situ method for evaluation of aggregate stability against splash erosion.
    Keywords: Aggregate stability, Fall-cone penetrometer, Splash erosion, Multiple rainfall simulator, Wet sieving
  • Somayeh Sefidgar Shahkolaie, Mojtaba Baranimotlagh *, Farhad Khormali, Esmael Dordipour Pages 15-29
    Introduction
     At present, contamination of water and soil resources is an important environmental challenge. Therefore, decontamination of such is a prerequirement for using these resources. Cadmium (Cd) and lead (Pb) often coexist in contaminated soils and there is currently no effective means for their concurrent removal. Concerns about their mobility and bioavailability have increased because of food safety, potential health risks and its detrimental effects on the ecosystems. The stabilization/solidification is a cost effective remediation method that prevents spreading of heavy metals in soil and water resources. In this process, contaminated soil reacts with amendments such as organic and liming materials to form low soluble or non-soluble stable materials. The objective of this study was to evaluate the effect of several low cost amendments on Cd and Pb stabilization by a sequential extraction method.
    Materials and Methods
    In this research, in order to investigate the effect of organic amendments (biochar 640°C, and biochar 420°C) and inorganic amendments (Pumice, Leca, Zeolite, and Bentonite) on Pb and Cd stabilization in a contaminated soil, an incubation experiment was carried out. One kilogram of each amended soil and the control soil were packed into respective pots. Soils were amended in the laboratory using biochar 640 (BI1), biochar 420 (BI2) bentonite (BE), pumice (P), leca (LE), and zeolite (Z). A control treatment (C) without adding amendment was also prepared. The amendment materials were applied at 1 and 5 percent wt. Each treatment was performed in three replicates and the samples were incubated in the dark at 14°C for 6 months. At the end of the incubation time, the potential bioavailability of Cd in non-amended and amended soils was evaluated by extraction with DTPA and ethylenediamine tetraacetic acid (EDTA). Total Cd (CdT) and Pb (PbT) was extracted by aqua regia (HNO3 + HCl) extraction. The chemical fractions of Cd and Pb were determined by a sequential extraction method which is a five-step chemical fractionation based on the work of Tessier et al. (1979). All statistical analyses were performed using SAS software. Means of different treatments were compared using LSD (P ≤0.05) test.
    Results and Discussion
    The results indicated that the additions of amendments to soils reduced the concentration of DTPA and EDTA-extracted Pb and Cd. The smallest concentration of Pb-extracted DTPA and EDTA was observed in organic amendments treated soil (biochar 640°C, and biochar 420°C) and treated with 5% biochar 640°C, respectively. The high sorbent capacity of the BI used in this study could be due to its high pH, high content of organic carbon and cation exchange capacity (CEC). The highest decreasing rate of DTPA and EDTA-extractable of Cd was observed in treated with 5% pumice and zeolite, respectively. Application of the amendments (except for 1% LE) decreased exchangeable fraction (F1) of Pb compared to the non-amended soil. Also, the amendments (except for 1% P, Z and BE) decreased exchangeable fraction (F1) of Cd compared to the non-amended soil. Although the biochar 640 (5%) showed the highest decreasing rate of exchangeable fraction (F1) of Pb and Cd, they increased the oxide (F3) and organic (F4) fractions, which might be due to its rich O-containing functional groups and high alkalinity leading to an increase in the binding of Cd and Pb to organic compounds and mineral oxides.
    Conclusion
    Results indicated that application of amendments was successful in lowering the potential bioavailability of Pb and Cd soils. The 5% biochar 640 treatment had the greatest decrease in extractable Pb. Also, the 5% zeolite and pumice treatment had the greatest decrease in extractable Cd. Application of BI resulted in a significant decrease in both Pb and Cd exchangeable fraction (F1). This reduction in the exchangeable fraction (F1) of Cd and Pb in the soil was due to an increase in the fraction of heavy metals bound to the soil organic matter (F4) oxides (F3) after BI addition. Enhanced precipitation or co-precipitation and complexation of metals with amendments led to the reduction of the solubility of the metals. The P, LE, BE, and Z altered the exchangeable fraction (F1) of Cd and Pb to the oxide fraction (F3) and the carbonate fraction (F3), respectively. Application of BI amendment causes the highest decreasing rate of solubility Cd and Pb, suggesting this as the suitable amendment for the remediation of Cd and Pb in contaminated soils.
    Keywords: Amendments, Bioavailability, Cadmium, Chemical fractions, Lead
  • Mansooreh Khaleghi, Azam Jafari *, Mohammad Hadi Farpour Pages 31-48
    Introduction
     Soil digital mapping represents a set of mathematical computations to predict the distribution of soil classes in the landscape. This approach relies on statistical relationships between measured soil observations and environmental covariates at the sampling locations. The need for digital soil mapping as an addition to conventional soil surveys results from a worldwide growing demand for high- resolution digital soil maps for environmental protection and management as well as projects of the public authorities. Digital soil data is increasing based on new processing tools and various digital data. The digital identification of soils as a tool for creating soil spatial data provides ways to address the growing need for high-resolution soil maps. The main objective of this study is to generate the digital soil map based on the legacy soil data.
    Materials and methods
    The study area is located in southeastern Iran, 330 km from Kerman city, in Faryab distinct. In this study, a Latin hypercube sampling design was applied and the sampling was done according to the difference in landforms (geomorphology map), topography (including digital elevation map) and geology. The geographic locations of 70 profiles were identified. Soil profiles were described according to U.S. Soil Taxonomy (Soil Survey Staff, 2014) and finally, the soil samples were taken from their diagnostic horizons. The collected soil samples were transferred to the laboratory, and some physical and chemical analyzes were performed based on routine standard methods. Environmental data include the parameters derived from the digital elevation model, Landsat satellite images (remote sensing indexes), geology map, geomorphic units (geomorphology map) and legacy soil map of the study area. All environmental variables were derived using ENVI and SAGA software. In this research, a multinomial logistic regression model was used to predict soil classes and the modeling was done in two scenarios: 1- modeling without the legacy soil map and 2- modeling with the legacy soil map. Estimation of predictive accuracy of soil classes was also done using the overall accuracy index and Kappa coefficient.
    Results and discussion
    The result of the modeling with the multinomial logistic regression method in two sets of input variables showed that the topographic position index is the most effective variable in predicting soil classes. This confirms topographic importance on soil genesis in the studied area. After topographic variables, the legacy soil data is an effective parameter in modeling. The legacy data of soil is a strong and valuable database for predicting soil characteristics. The old soil map consists of the salt surfaces and Inceptisols order. Unlike the hot and arid climate of the study area, Inceptisols order was identified in the old soil map. Soil survey with very small scale was probably led to generalization of the studied soils and hiding the main soils of the study area. However, the small-scale mapping and the presentation of different soils in the region do not prevent the presence of the old soil map as an important predictor. It seems that there is a high concordance between the borders of old soil map and the described soils diversity in the study area. The matching and concordance between the boundaries of the old map and the described soil profiles help the model to differentiate different soils, although the correspondence between the soils type of the old soil map and the observed soils can play a more effective role in predicting by the model. Soil legacy information is a powerful and valuable database for predicting any feature of the soil. In both predicted maps, four major groups of Haplosalids, Haplocambids, Haplocalcids and Torriorthents were identified. The great group of Torriorthents is located in the north of the region and in the alluvial fan landform. Haplosalids great groups were most commonly found in clayey surfaces. Haplocambids and Haplocalcids great groups are located more in the geomorphic surface of the cultivated fan and the piedmont plain, respectively. The results of the predictive quality of the logistic regression model showed that the number of well-estimated soils in the presence of the old soil map is more than when there is no old soil map in the modeling. In addition, the results of the validation of the models showed that the map accuracy and kappa index increased in presence of the legacy soil map. As a result, the model's validation indices including the map purity and Kappa index increased from 0.47 and 0.16 to 0.63 and 0.43, respectively. In both models, the highest accuracy of the estimation was obtained for Haplocambids great group.
    Conclusions
    The results showed that topographic position index was the most important and powerful variable for forecasting in both models, and confirms that topography or relief is the most important soil forming factor in the study area. Using the legacy soil map as one of the environmental variables in modeling, efficiency and accuracy are more accurate than modeling without the legacy soil map. If the old soil maps as legacy information are used in digital soil mapping, the similarity and matching of the soils of the studied area shoud be cheched even with the very small scale because the high concordance leads to rational prediction, and random and chance predictions do not occur.
    Keywords: Multinomial logistic regression, soil great group, auxiliary variables, legacy soil map
  • Samira Alvani, Saeid Hojati *, Ahmad Landi Pages 49-65
    Introduction
     Pollution of the environment to heavy metals is one of the major problems of today's world. Following the development of industries, as well as increasing agriculture in response to the growing population, the overuse of chemical fertilizers, mining activities, the production and disposal of waste waters and sewage sludge, etc., the entry and accumulation of heavy metals in the environment has increased. There are several methods for removing heavy metals from wastewaters. Among the common methods for removal of heavy metals, adsorption, in particular using inexpensive natural adsorbents, due to the ease of implementation and high efficiency is a cost-effective and economical technique. Palygorskite is a fibrous mineral common in clay fractions of soils of arid and semi-arid regions of the world. Although there are several studies applying palygorskite as a suitable mineral for cleaning of wastewaters, however, few studies have been carried out to evaluate the ability of nanosized particles of such clay minerals for removal of heavy metals from the environment. Therefore, this study was conducted to measure the ability of palygorskite nano- and micro-sized particles to adsorb lead and copper from aqueous solutions. 
    Materials and Methods
    Kinetic experiments were carried out at 11 different contact times (5, 10, 20, 30, 60, 120, 240, 480, 720, 1440, and 2880 min) using solutions containing 150 mg / l of lead and copper elements at pH=5. Palygorskite used in this study was purchased from Tulsa Co., Spain Then, micron (
    Results and Discussion
    The results illustrated that in the so-called samples as nanosized palygorskite, about 50% of the particles in the sample was found smaller than 100 nm in size, and in this case no samples of particle size of 100 nm and smaller were observed in those so-called palygorskite microparticles. The results indicated that by increasing the contact time and reducing the mineral particle sizes from micron to nanoscale, more amounts of lead and copper heavy elements adsorbed onto the mineral. This is due to an increase in the exposure of active sites on the adsorbent surfaces by the pollutant. When the data were fitted with the pseudo first order, pseudo second order and intraparticle diffusion kinetic models, it was revealed that the pseudo second-order kinetic model with a determination coefficient (R2) of 0.99 was the best model describing kinetics of study. Besides, the lower values of the chi-square (ᵡ2) in fit with the pseudo-second-order kinetic model as compared to those in the pseudo first-order model show a greater similarity between the pseudo-second-order kinetic model and the experimental data. The isotherm of Pb and Cu adsorption was also studied using Langmuir and Freundlich adsorption models. It was observed that the data had a better coordination with the Langmuir model with a determination coefficient of 0.99. By increasing the initial concentration of the lead and copper in the solution, their distribution coefficient (Kd) decreases. This suggests that although with increasing initial concentration of lead and copper, their adsorption increased by palygorskite mineral, however, by increasing the initial concentration of heavy metals, the remaining concentration of these elements also increased. The results also illustrated that both micro- and nanoparticles of palygorskite show more affinity to adsorb lean than copper from solutions.
    Conclusion
    In general, it can be concluded from this study that adsorption of lead and copper by palygorskite nanoparticles depends on the contact time and the adsorbent size. Besides, the use of this mineral could be considered as a suitable, feasible and environmentally friendly way to remove lead and copper from aqueous solutions.
    Keywords: Nanoparticles, Palygorskite, Kinetic, Lead, Copper
  • Masoomeh Najafinia, Farhad Khormali *, Farshad Kiani, Mojtaba Baranimotlagh Pages 67-82
    Introduction
     Loess sediments of northern Iran represent several cycles of climate change and evolution of the landform for the mid-to-late Quaternary. Climate change in elevations of Iran and its surrounding areas is very controversial in the mid and late Quaternary, and has been discussed in the past according to rainfall and rainfall periods and between rainfall, glacial and inter-glacial. Paleomegnatic results also indicate that Early Pliestocene loess (Reddish loess) have accumulated between, 1.8 to 2.4 million years ago. However, pedogenic processes and the effects of past climate in these soils still have not been fully investigated. The loess deposits in northern Iran are a valuable archive of regional paleoclimatic and paleoenvironmental information. Micromorphology is an important technique to identify and interpret the loess- paleosol for paleoclimate studies. Microscopy is a method of studying undisturbed soil samples with the help of microscopic techniques (and sometimes with ultramicroscopic ones), in order to identify their constituents, determine their mutual relations in space and time and interpret their formation conditions. Micromorphology uses these characteristics to make interpretations, generally on the soil formation processes. This study aimed to conduct a micromorphological investigation on the early Pleistocene loess and to compare it with the modern loess derived soils in Agh-Band, Yelli-Badrag and Qareh-Agach in loess plateau of eastern Golestan.
    Materials and Methods
    The study area is located in semiarid climate in loess Plateau east Golestan. Six profiles were selected and studied. Physicochemical properties such as soil texture, acidity (pH), electrical conductivity (EC), saturation moisture (SP), organic carbon (OM), cationic exchange capacity (CEC) and calcium carbonate equivalent (CCE) were measured in the laboratory. Then, soil samples were prepared from each horizon for micromorphology studies. For micromorphological studies, thin sections were prepared from undisturbed, oriented and dry clods by standard methods and described under a polarizing optical microscope.
    Results and Discussion
    Comparing the results of physicochemical properties (such as color, carbonate percentage, the cation exchange capacity, etc.) in paleosol and modern loess soils indicates that the in paleosols, soil forming processes have passed several stages. The existence of the argillic horizons and the evolved calcic in paleosols and their absence in the modern soils in which they are present, indicates the change in soil formation conditions. The change in the color of paleosols also represents the soil moisture and the more suitable conditions of the past climate (temperature, and especially rainfall) in comparison with the present climate of the region. This color change was due to activation of soil formation processes in paleosols. All paleosol samples had a higher clay content than the late modern loess soils of the Pleistocene, suggesting favorable climatic conditions for soil formation processes and the development of more ancient soil than parent materials. Reducing annual precipitation decrease soil pedogenesis.
    Conclusion
    Comparison of the results obtained from paleosols of early Pleistocene with modern soils indicates that the time and climate change caused alterations in the soil micromorphology features (such as the type and amount of pores, soil structure and b-fabric and pedofeatures etc.). One of the most important pedofeatures was clay coating around void, presented only in buried paleosols, which is the evidence for moist climate conditions and subsequently enough leaching for clay translocation. Further, the presence of planar void caused by shrink and swell of clay is evidence for evolution in the paleosols. In argillic horizons of paleosols, dominant b-fabric is speckled due to carbonate leaching while in calcite horizon, it is crystallitic b-fabric. The micromorphological index of soil development calculated, showed that these red-colored deposits are formed under an annual precipitation of about 450- 650mm which represents more humid conditions at the time of their formation than the modern loess soils. In modern soils derived from recent loess, lack of clay coating can be a reason for weakly developed soil formation.
    Keywords: Loess-paleosol, Pleistocene, Micromorphology, Golestan Loess-paleosol
  • Amir Rahimi, Behnam Doulati *, Saied Heydarzadeh Pages 83-97
    Introduction
     Nutritional deficiencies (e.g. Iron, Zinc, Manganese and Boron) account for almost two‐thirds of the childhood death worldwide. Most of those afflicted are dependent on staple crops for their sustenance. Declining soil fertility in many countries, duo to continuous cropping systems, has reduced soil production capacity affected by depletion of soil nutrient without proper replacement. Soil application of prepared humic substances is not economical, but the response to foliar sprays has the potential to be economical because the relatively small quantities are needed. Foliar application is one of the swift response methods for plants to add fertilizer, which leads to dispel of nutrients deficiency and providence in the use of chemical fertilizers. The solubility of nutrients decreases in soils with high acidity or undesirable chemical composition and can be possibility of ionic competition (Antagonism) or the accumulation of nutrient in soilcanlee resulthed. Therefore, adsorption of nutrients and root growth will be inappropriate. On the other hand, the application of humic substance with improving physical, chemical and biological conditions causes an increase in adsorption and soil fertility. Using humic substances is another benefit of the reduction of environmental pollution in order to achieve sustainable agriculture. A sugar beet is a plant whose root contains a high concentration of sucrose and which is grown commercially for sugar production. Sugar beet is one of the strategic crops and is widely cultivated in the West Azerbaijan region. So, the aim of this study was to investigate the application of humic substances and micronutrient on some quantitative and qualitative characteristics of sugar beet.
    Material and Methods
    This study was carried out as a randomized complete block design with six levels of humic substance (0, 200, 300, 400, 500, 600 kg ha-1) and foliar application of micronutrients including Fe, Zn, B, and Mn with 3 replications. Physicochemical properties of soil (calcium carbonate equilibrium, pH, OC, EC, micro and macro elements, soil texture) were determined by standard methods. There fore, quantitative and qualitative characteristics of sugar beet including total sugar content, pure sugar content, and molasses sugar content, Na, K and N content in root, alkalinity, sugar extraction coefficient, root yield and pure sugar and total sugar yield were determined in sugar beet samples.
    Results
    The results showed that the application of humic and micronutrient was significant in qualitative and quantitative characteristics of sugar beet. Maximum root yield (68.96 ton ha-1) was obtained in the Mn treatment. The highest of pure (16.30%), gross sugars (18.68%) and sugar extraction coefficient (87.25%) was observed in B and 500 kg ha-1 of humic asid treatment. Humic acid application increased nitrogen (27.58%) and root yield (29.08%) compared to control. Also, micronutrient and humic substance application reduced the molasses sugar content and increased potassium in the root of sugar beet. So that the highest (3.48%) and lowest (2.37%) amounts of molasses sugar were obtained in control and 500 kg ha-1 humic acid plus B treatment respectively. Boron is much required for cell division and development in the growth regions of the plant near the tips of shoots and roots. It also affects sugar transport and appears to be associated with some of the functions of calcium.
    Conclusion
    According to the results of this study, foliar application of humic substance and micronutrient improved qualitative and quantitative characteristics of sugar beet. The root and refined sugar yields are among the most important components in sugar beet production. Also, treatment of 600 kg ha-1 of humic acid and Mn spraying had the greatest effect on the root and gross sugars yield in sugar beet. Also, the amount of molasses sugar decreased with increasing sugar content and replacing potassium instead of harmful elements. Application of Mn and B may need to be considered for sugar beets. Foliar fertilization with Mn has the beneficial effect mainly on such features like White sugar yield, root, gross sugars yield, and the number of leaves per single sugar beet plants. It can be concluded that the contemporary use of humic substance and micronutrient is recommended in order to achieve adequate yield and preserve the environment.
    Keywords: Extraction coefficient, Humic acid, Sugar beet, Pure sugar, Root yield, Sustainable agriculture
  • Soraya Taheri, Abdolmajid Ronaghi *, Reza Ghasemi, Sedigheh Safarzadeh Shirazi Pages 99-111
    Introduction
     Zinc deficiency is aggravated mainly in arid and semi-arid regions, due to low organic matter and soil moisture as well as high levels of pH and salinity. Maize which serves as staple food is sensitive to Zn deficiency. One of the mechanisms by which plants can adapt to nutrient deficient soils has suggested producing and secreting organic substances, including aliphatic low molecular weight organic acids, into the rhizosphere for mobilization and uptake of nutrients. Under Zn deficiency, plants tend to modify rhizosphere in order to increase Zn phyto-availability. Zinc mobilization efficiency is dependent upon the amount and type of organic acids exuded by plant roots and physiochemical properties of soil. Therefore, the objectives of the present study were to investigate the influence of Zn deficiency on the shoot and root dry matter yields and the release rate of organic acids (malic, citric and acetic acids) commonly identified in root exudations of maize under Zn deficiency conditions.
    Materials and Methods
    Seeds of maize (SC703 and SC704) were surface sterilized and germinated in perlite moistened with distilled water. After seven days, the seedlings were transferred to 5-L containers with continuously aerated nutrient solution. Three Zn levels (0, 0.5, and 1 µM) were added to nutrient solutions. Ten weeks after maize emergence, intact plants were removed from nutrient solution and after two hours of the onset of the light period, roots samples were in opaque vessels containing fresh solution.  The volume of collected solution was sufficient to submerge the whole maize roots samples. After three hours, roots samples were removed from the vessel and solution containing roots exudates was filtered and frozen at −20 ◦C until analysis of organic acids was performed. Organic acids were analyzed using high performance liquid chromatography (HPLC). Organic acids in the samples were identified by comparison with the retention time and absorption spectra of pure standards including malic, citric and acetic acid. The 1-cm washed root segments were placed in a beaker containing 10 mL deionized water and then root samples were immersed at 30◦C for three h, and then conductivity of solution was measured. The samples were boiled for 2 min, cooled to room temperature (25◦C) and then EC samples were measured. The electrolyte leakage was calculated as follows:   Where C1 and C2 are electrical conductivities measured before and after boiling, respectively.  Roots and shoot samples were ignited at 580 ◦C in an oven for 5 h and Zn concentration measured using atomic absorption spectroscopy (AAS).
    Results and Discussion
    In both genotypes shoot dry matter yield (SDMY) was significantly improved with increasing Zn concentration in nutrient solution. The highest value of SDMY was 19.8 g and belonged to Zn-adequacy level (1 µM) in SC703 genotype which had no significant difference with SC704 under the same treatments. There was no significant difference between Zn-sufficient and Zn-deficiency (0.5 µM) in SDMY in genotype SC703 whereas, a significant difference was observed at the same treatments in genotype SC704. The lowest value of SDMY was 14.7 g and belonged to the Zn-free treatment for genotype SC704. Root dry matter yield (RDMY) significantly increased with increasing Zn concentration in nutrient solution in both genotypes. The highest value of RDMY was 9.6 g and belonged to the treatment of Zn-adequacy for SC703 genotype which had no significant difference with SC704 genotype under the same treatment. The lowest value of RDMY was 4.8 g which was observed in Zn-free treatment for SC704 genotype. Results showed that the rate of organic acid exudation in both Maize genotypes decreased with increasing Zn levels in nutrient solution. The highest rate of MA exudation (6.6 mg /g root dry weight) was observed in Zn-free (Zn0) treatment in SC703 genotype and the lowest rate (1.98 mg g RDW-1) was observed in 1µm Zn treatment in SC704 genotype. Similar to MA, the rate of citric acid (CA) exudation rate significantly decreased with increasing Zn levels in nutrient solution. The highest rate of CA exudation rate was 1.06 (mg gRDW-1) and observed in Zn-free (Zn0) SC703 genotype. The lowest rate of CA was observed in 1µm Zn treatment SC704 genotype 0.2 (mg gRDW-1). The concentration of acetic acid (AA) was below the detection limit of HPLC in Zn sufficient and Zn deficiency treatments. However, AA concentrations in Zn-free were 0.66 and 0.25 (mg gRDW-1), respectively in SC703 and SC704 genotypes.    The rate of MA was significantly higher than CA (4times) and AA (15 times higher). All organic acids exudation rate decreased with increasing Zn concentration in nutrient solution. There was a negative relationship between root and shoot Zn concentration with MA and CA exudation rate. MA, CA and AA exudation rate decreased as the concentration of Zn increased in root and shoot of maize. Roots membrane permeability decreased with increasing Zn concentration in nutrients solution which led to the reduction in root exudations. In both maize genotypes, the highest rate of root membrane permeability belonged to the Zn-free treatment (Zn0) which had the highest root exudation of organic acid and the lowest rate was observed in1µM Zn level  with the lowest rate of organic acid exudation. It seems that Zn concentration in maize shoot control the release of root exudation of organic acids. In general, based on the results it can be concluded that SC703 genotype was more tolerant to Zn-deficiency compared to SC704 genotype partly due to the higher release rate of root organic acids. Further investigation is required to fully understand the physiology of organic acids release under Zn deficiency conditions.
    Keywords: Corn, Malic acid, Citric acid, Acetic acid, Zn deficiency
  • Serve Moradi, Kamal Nabiollahi *, Syed Mohammad Taher Hossaini Pages 113-129
    Introduction
     Soil quality is the capacity of soil function to sustain plant and animal productivities, to maintain or enhance water and air quality and to support human health. Slope position and deforestation are known to influence soil quality and assessing the soil quality degradation is important to soil management. Soil-quality indices are a common and easy way to quantify soil quality; they can improve understanding of soil ecosystems and allow more efficient soil management Two soil indicator selection approaches, total data sets and minimum data sets have been widely used to evaluate soil quality. The region of Marivan in Kurdistan province is one of the forested areas of Zagros which has been threatened due to population growth and increasing demand for food and, some parts are now under agriculture land use. Based on the present reports, deforestation and cultivation on the sloping areas have started almost 30 years ago. The aim of this research was to assess the effect of forest degradation and slope position on soil quality index.
    Materials and Methods
    The study area is located in Kurdistan Province, about 10 km northeast of Marivan city, west Iran (46°24΄ 46°40΄E, 35°42΄ 35°50΄N). Two adjacent sites were selected, consisting of a natural forest and deforested cultivated land on a hill slope. Average annual precipitation and temperature are 813 mm and 13.8 °C, respectively. Soil moisture and temperature regimes are Xeric and Mesic, respectively. Forests of the study area are relative intensive and their main forest vegetation is oak. In this study, 24 soil samples (0–20 cm depth) were taken from four slope positions (shoulder, back slope, foot slope and toe slope) of forest and adjacent deforested cultivated soils. Eight profiles (on each slope positions of both land uses) were also described. Fifteen soil properties: pH, electrical conductivity, sodium adsorption ratio, organic carbon, cation exchange capacity, carbonat calcium equivalent, soil erodibility, soil porosity, mean weight diameter of aggregates, available water, soil microbial respiration, available phosphorous, available potassium, total nitrogen, bulk density, were measured for 24 soil samples (0–20 cm depth). These Fifteen soil properties were applied as the total data set. Then, seven soil properties were selected as minimum data set using principle component analysis. Weight and score of each property were found using communality and scoring function (including more is better, low is better and optimum) and finally weighted additive and nemoro soil quality indices was computed.
    Results and Discussion
    Seven soil properties (including soil organic carbon, cation exchange capacity, bulk density, soil erodibility, plant available water content, available potassium and total nitrogen) were selected as total data set using principle component analysis. The soils formed in low slope positions had higher depth and evolution compared to high slope positions. The results also showed land use change of forest land to cropland has led to degradation of Mollisols. The results showed that the mean values for weighted additive and nemoro soil quality indices in the deforested were significantly lower compared to forest. The mean values for weighted additive and nemoro soil quality indices in the shoulder were significantly lower compared to other slope position. significantly Strong Pearson correlation coefficients (0.98) were obtained between computed weighted additive soil quality index using total data set and a minimum data set.
    Conclusion
    The results showed that forest degradation in the Marivan region led to a decrease in weighted additive and nemoro soil quality indices through a significant reduction of organic carbon, microbial respiration, total nitrogen, CEC, soil porosity and available moisture and significant increasing of bulk density, pH, SAR and soil erodibility. Forest degradation and land use change also due to cultivation led to decrease in the organic carbon content and soil structure degradation of Mollic horizon. Therefore, Mollic horizon has converted to Ochric horizon and Entisols and Inceptisols have formed in cropland land use. Moreover, the results showed different slope positions affect weighted additive soil quality index and mark significant difference. The results also showed that using the weighted additive soil quality index and minimum data set method can adequately represent total data set (R2=0.98) and thus reduce the time and cost involved in evaluating soil quality. Slope positions and where forest was converted to agriculture were characterized by low values of weighted additive soil quality index, suggesting a recovery of soil quality through changing to sustainable practices.
    Keywords: Soil quality, minimum dataset, principle component analysis, hill slope
  • Ali Abdolahi, Mehdi Taghavi Zahedkolaei *, Mojtaba Norouzi Masir, Abdolamir Moezzi Pages 131-146
    Nanotechnology has created a range of new applications in different stages of agriculture. The application of Nano-fertilizers for plants is of vital importance because of its unique properties, such as the specific surface and high reactivity. Many studies have investigated the effect of metal nanoparticles on yield and concentration of elements in the plant. The present study was conducted with the aim of investigating the effects of Functionalized Iron Oxide Nanoparticles (FIONPs) on plant yield, concentration and uptake of Zinc in root and shoots of wheat under greenhouse cultivation in a calcareous soil.
    Materials and Methods
    This study was conducted in the greenhouse condition as a randomized complete design with three replications. Treatment consisted of functionalized iron oxide nanoparticles (Hydroxyl: OH, Carboxyl: COOH and Amine: NH2) each at three levels (100, 200 and 300 mg.kg-1), ZnSO4 (40 kg.ha-1) and Control. During the experiment, some parameters such as the plant height and chlorophyll index were measured. At the end of the cultivation period, dry weight and Zn concentration of root, shoot and grain was determined using Atomic absorption apparatus (Perkin elmer A_Analyst 200 model). Likewise, content of soil available Zn was measured using DTPA.
    Results
    The amount of available zinc in all levels of iron oxide nanoparticles, except Amine iron oxide nanoparticles (at levels of 200 and 300 mg / kg), was significantly (P<0.01) increased compared to control. The maximum amount of soil available Zn were observed in levels of 300, 200 and 100 mg.kg-1 Carboxyl iron oxide nanoparticles with 83.64, 70.91 and 63.64% increment compared to control, respectively. Effect of treatments of functionalized iron oxide nanoparticles and zinc sulfate on chlorophyll content, plant height and dry weight of shoots was significant (P<0.01). The maximum yield of root and shoot was obtained at the level of 300 mg.kg-1 of Carboxyl iron oxide nanoparticles with 34.74 and 25.1% increment compared to control, respectively. The maximum grain yield was observed at the level of 300 mg.kg-1 of Carboxyl iron oxide nanoparticles with 36.51% increment compared to control. The maximum chlorophyll content was obtained in Carboxyl iron oxide nanoparticles (at level of 300 mg. kg-1) with 11.38% increment compared to control. The maximum of Zinc concentration in root, shoot and grain was observed at the level of 300 mg.kg-1 carboxylic oxide nanoparticles with 103.62, 159.26 and 26.87% increment compared to control, respectively.
    Conclusions
    The results showed that application of FIONPs improved soil pH and subsequently available zinc of soil. Also, nanoparticles increased the yield, concentration and uptake of zinc in root, shoots and grain of wheat. Therefore, based on the obtained results from this study, it can be said that use of new strategies such as nanoparticles can be useful in improving soil conditions and bioavailability of Micronutrient like Zinc and reducing chemical fertilizers.
    Keywords: Nanoparticles, Iron Oxide Nanoparticles, Zinc Concentration, Yield, wheat