تاثیر ادوات مختلف خاک ورزی بر برخی خصوصیات فیزیکی و جابجایی خاک

این تحقیق در راستای انتخاب مناسب‌ترین ادوات خاک‌ورزی از نظر حفظ ویژگی‌های فیزیکی و انتقال خاک انجام شد. در یک طرح آزمایشی کرت‌های نواری خرد شده در قالب طرح بلوک‌های کامل تصادفی با سه تیمار اصلی خاکورزی (1) گاوآهن برگردان‌دار، (2) گاوآهن بشقابی و (3) گاوآهن قلمی و دو تیمار فرعی شیب زمین در چهار سطح (شامل0 ،3 ، 6 و 8 درصد) و تیمار سرعت در سه سطح (شامل 2، 5 و 8 کیلومتر در ساعت) اجرا شد. ضریب انتقال ذرات خاک و برخی از ویژگی‌های فیزیکی خاک شامل چگالی ظاهری خاک، میانگین وزنی قطر ذرات، درصد پایداری‌تر خاکدانه‌ها، تخلخل تهویه‌ای، میانگین هندسی قطر ذرات خاک و ظرفیت زراعی بعد از خاک‌ورزی اندازه‌گیری شدند. نتایج تحلیل داده‌ها نشان دادند که نوع گاوآهن تاثیر معنی‌داری بر میانگین وزنی قطر ذرات و چگالی ظاهری خاک دارد. میانگین وزنی قطر خاکدانه‌ها پس از تیمار با گاوآهن برگردان‌دار بطور معنی‌داری بیش از میانگین وزنی قطر خاکدانه‌ها پس از تیمارهای خاک با گاوآهن‌های قلمی و بشقابی بود. همچنین چگالی ظاهری خاک‌ها پس از استفاده از گاوآهن برگردان‌دار کمتر از چگالی ظاهری خاک‌ها در دو تیمار دیگر بود. اندازه‌گیری ضریب انتقال خاک‌ورزی نشان داد که بیشترین ضریب انتقال خاک مربوط به گاوآهن برگرداندار بود. همچنین بالاترین ضریب انتقال خاک در کلیه ادوات خاک‌ورزی مربوط به لایه سطحی عمق خاک‌ورزی بود و در این عمق هم ضریب انتقال خاک برای گاوآهن برگرداندار بیش از گاوآهن‌های بشقابی و قلمی بود.

the effect of different tillage instruments on some soil physical characteristics and soil translocation

introduction tillage is defined as disturbing the soil and changing soil physical condition of seedbed and root zone and making it suitable for cultivation. soil physical characteristics like soil moisture and temperature conduction, bulk density, porosity and particle size are changed in the following of soil tillage. tillage also increases water infiltration rate and plays an important role in soil moisture protection and decreasing flood hazards in arid and semi arid regions. molboard plough is currently implemented for tillage in different parts of iran including chaharmahal va bakhtiari province. there are evidences which show moldboard plough triggers physical soil characteristics deterioration and soil tillage erosion. tillage translocation coefficient, as a component of tillage erosion, is defined as the amount of soil transition for 1 m width of tillage instrument. comparing the impacts of available tillage instruments with moldboard plough on physical soil characteristics, soil transition and their efficiency may encourage field managers to substitute other instruments with moldboard plough. this research aimed to: 1) study the impacts of the currently available tillage instruments (moldboard, disk and chisel plough) on some prominent physical soil characteristics and 2) compare soil translocation coefficients of the mentioned tillage instruments. materials and methods this research was executed in research training field of shahrekord university, shahrekord county, chaharmahal va bakhtiari province, iran. a split plot experimental design with complete randomize block was considered with 3 major treatments of tillage instruments (molboard, disk and cchisel plough), minor treatments of slope (0, 3, 6 and 8%) and tillage speeds (2, 5, and 8 km h 1) and 3 replications. the conventional tillage depth of 25 cm was adjusted for all three tillage instruments. standard protocols were applied and soil electrical conductivity (ec), ph, calcium carbonate equivalent (cce), organic matter (om) and soil texture components were measured before tillage application. soil field capacity (fc), mean weight diameter (mwd) of aggregates, geometric mean diameter (gmd) of aggregates, aeration porosity (fa), bulk density (ρb) and water stable aggregates (wsa) were measured using standard protocols after tillage implementations. colored gypsum cylinders were used as indicators for detecting soil translocation. the transition distance of the colored gypsum cylinders of each layer of tillage depth (0 9, 9 18 and 18 25 cm) was measured using tape meter or ruler and mean transition for each layer were calculated. in the next step the depth weight soil translocation was calculated for each tillage instrument. results and discussions chemical analysis of soil samples showed that soils were non saline, soil om content was less than 1% and cce of soil samples was relatively high. physical soil analysis of soil samples before tillage implementation indicated that there was not any restriction for plant root development and aeration as ρb was relatively low and aeration porosity was 10% <, respectively. analysis of variance (anova) indicated that the effects of tillage type on mwd and ρb were significant (p < 0.05). comparing the means of mwd and ρb induced by tillage instruments (duncan method) revealed