پديد آورندگان :
برزويي، مجيد دانشگاه فردوسي مشهد - دانشكده كشاورزي , ايزدي دربندي، ابراهيم دانشگاه فردوسي مشهد - دانشكده كشاورزي , راشد محصل، محمد حسن دانشگاه فردوسي مشهد - دانشكده كشاورزي , راستگو، مهدي دانشگاه فردوسي مشهد - دانشكده كشاورزي , حسن زاده خياط، محمد دانشگاه علوم پزشكي مشهد - دانشكده داروسازي
كليدواژه :
بقاياي علف‌كش , پايداري , زيست سنجي , نيمه عمر
چكيده فارسي :
به منظور بررسي تأثير كودهاي آلي و زيستي بر پايداري علف‌كش تريفلورالين در در خاك آزمايشي در سال 1391 در مزرعه تحقيقاتي دانشكده كشاورزي دانشگاه فردوسي مشهد انجام شد. آزمايش در قالب طرح بلوك‌هاي تصادفي در سه تكرار اجرا شد. تيمارهاي آزمايش شامل كاربرد كودهاي آلي (اسيد هيوميك 85 درصد و اسيد فوليك 12 درصد)، كودهاي زيستي (نيتروكسين و فسفات بارور 2) و مخلوط آن‌ها و مقادير كاربرد تريفلورالين در سه سطح صفر، 480 و960 گرم ماده مؤثره در هكتار ( ترفلان تجاري با خلوص 48 درصد) بودند. براي تعيين غلظت تريفلورالين در خاك، 0، 3، 7، 15، 30، 60، 90، 120 روز پس از كاربرد آن، نمونه‌گيري از عمق 0 تا 10 سانتي‌متري خاك انجام شد. استخراج باقيمانده تريفلورالين از خاك به روش ميكرو استخراج مايع-مايع با چگالي كم انجام و باقيمانده آن با استفاده از دستگاه GC تعيين شد. نتايج نشان دادند كه ماندگاري تريفلورالين در خاك، با كاربرد كودهاي آلي و زيستي كاهش يافت. بطوري‌كه كمترين نيمه عمر آن (26/55 و 26/41 روز) به ترتيب در تيمار مربوط به كود آلي و كود زيستي و مقدار كاربرد480 گرم ماده مؤثره تريفلورالين در هكتار و بيشترين نيمه عمر آن (106/64 و 78/77روز) بترتيب در كاربرد 960 و 480 گرم ماده مؤثره تريفلورالين و در شرايط بدون كاربرد كود مشاهده شد. بطور كلي بر اساس نتايج حاصل از اين آزمايش كاربرد كودهاي آلي و بويژه كودهاي زيستي مي‌تواند نقش مهمي در كاهش ماندگاري علف‌كش تريفلورالين در خاك داشته باشند. اين كودها بويژه در مزارعي كه خطر خسارت پسماند اين علف‌كش در محصولات تناوبي وجود دارد، مي‌توانند نقش مهمي در كاهش آن داشته باشند.
چكيده لاتين :
Introduction: Herbicides that persist in soil are of benefit to farmers seeking to control late emerging weeds
in cultivated crops, and to managers looking for long-term vegetation control on rights-of-ways and industrial
sites. Herbicides that persist in soil can also create problems for farmers who want to diversify their rotation into
subsequent crops which may be sensitive to certain herbicide residues. Several factors mainly soil factors,
climatic conditions, and herbicide properties determine the herbicides persistence in soil. Trifluralin is one of the
important soil applied selective, pre-sowing or pre-emergence herbicide used to control many annual grasses and
broadleaf weeds in a large variety of crops. It is a generally regarded as a moderately persistence herbicide with
a half-life time of 1.5 to 6.5 months. Some studies, however, have reported higher half-life times varying from
7.5 to longer than 12 months. These results have been generally obtained at sites with very dry or very cold
climates in which soil is frozen over winter. Normally Residual herbicides extend the period of weed control,
increasing the efficiency of weed management practices. However, they may persist longer than desired and
injure or kill subsequent rotational crops. Thus, most herbicide labels include crop rotation guidelines, but
rotational restrictions are often not listed for many crops. This experiment was carried out to determine trifluralin
soil persistence affected by its dose and application some organic and biofertilizers.
Materials and Methods: In order to study the effect of some organic and biofertilizers on trifluralin
herbicide persistence in soil, an experiment was conducted as a factorial arrangement in completely randomized
block design with three replications in a cotton field at Ferdowsi University of Mashhad. Experimental factors
included trifluralin (EC 48 %) dose at two levels (480 and 960 g a.i. ha-1), application of organic fertilizers at two
levels (Humic acid (85 %) and folic acid (12 %) and biofertilizers application at two levels (Nitroxin and fertile
phosphate2). To determine the trifluralin soil residue, soil samples were taken from 0 to 10 cm soil depth during
3, 7, 15, 30, 60, 90 and 120 days after herbicide application and were kept in a freezer (-18 oC). For trifluralin
soil residue, gas chromatography technique was used. The trifluralin value recovered from soil at different time
intervals for each treatment was fitted in the first order kinetic equation according to:
C = C0e–kt (1)
Where C denotes the amount of trifluralin recovered from soil at time t, C0 is the amount of trifluralin
recovered at t = 0 interval; λ represents the degradation constant, and t is time in days. The DT50 (half-life) and
DT90 (the time required to disappear 90 % of herbicide) were calculated as follows:
k k
DT ln 2 0.693
50
(2)
k k
DT ln10 2.3
90
(3)
Results and Discussion: Results showed that application of organic and biofertilizers significantly reduced
trifluraline persistence in soil. The lowest trifluralin half-life time was observed for organic and bio-fertilizer
application equal to 55.26 and 41.26 days, respectively, at the dose of 480 g a.i ha-1 of trifluralin. The highest
half-life times equal to 106.64 and 78.77 days were observed in control treatment without application of
fertilizers for the trifluralin dose of 960 and 480 g. a.i ha-1, respectively. Application of organic and biofertilizers
plays important role in reducing of trifluralin soil residue and persistence. Therefore, the mentioned fertilizers
have positive effects in fields where there is a risk of damage of trifluralin residue for rotational crops.
