افزايش كارايي انرژي با تغيير شكل هندسي شياربازكن بيلچه‌اي

Increasing energy efficiency by geometric modification of hoe-type furrow opener

امروزه خاك‌ورزی حفاظتی به دلیل حفاظت از آب و خاك و صرفه جویی در مصرف انرژی و زمان، رواج بیشتری پیدا كرده است. یكی از نیازهای اصلی برای اجرای این سیستم از جمله روش بی‌خاك‌ورزی دسترسی به ادوات ویژه از جمله كارنده‌های خاص می‌باشد. در روش بی‌خاك‌ورزی قبل از ورود ماشین كاشت هیچ‌گونه عملیاتی بر روی خاك انجام نشده و بقایای محصول قبلی هنوز در سطح خاك باقی است، لذا بذركار و مخصوصاً شیاربازكن آن می‌بایست ساختار ویژه‌ای داشته باشد. از این رو به منظور دستیابی به شیاربازكن مناسب برای كشت مستقیم در شرایط دیم با اعمال تغییراتی بر روی شیاربازكن بیلچه‌ای (شاهد) دو نمونه جدید به نام‌های O1 و O2 ساخته شد و سپس سه شیاربازكن در سه سرعت پیشروی از لحاظ نیروی وارد بر شیاربازكن در شرایط آزمایشگاهی و از نظر تأثیر بر عملكرد محصول در شرایط مزرعه‌ای، به روش آماری اسپلیت پلات در قالب بلوك‌های كامل تصادفی، مورد مقایسه قرار گرفتند. نتایج نشان داد از نظر نیروی وارد بر شیار بازكن‌ اختلاف بین تیمارها معنی‌دار می‌باشد. نیروی افقی در شیاربازكن O1 نسبت به شاهد 4/3 درصد كاهش و در شیاربازكن O2، 8/2 درصد افزایش نشان داد. تعداد بوته سبز گندم و عملكرد محصول در مزرعه‌ نشان داد، شیاربازكن O2 با میانگین 48 بوته در متر نسبت به شیاربازكن شاهد 24 درصد و نسبت به شیاربازكن O1، موجب افزایش 33 درصدی بوته‌های سبز شده گردید. همچنین شیاربازكن O2 با میانگین عملكرد 48/3 كیلوگرم دانه در كرت (دو رفت در 20 متر) نسبت به دو شیاربازكن دیگر حدود 36 درصد افزایش عملكرد نشان داد. براساس نتایج به‌دست‌ آمده شیاربازكن O2 با توجه به افزایش عملكرد (انرژی ستانده) و اختلاف كم در نیروی مورد نیاز (انرژی ورودی) دارای بازده انرژی بهتری بوده و می‌تواند گزینه مناسب برای كشت مستقیم گندم در شرایط دیم باشد.

<strong >Introduction </strong > Direct planting becomes more common in the recent years, because it conserves soil and water as well as it saves energy and time. However, this technology needs special implements such as seed planter. Given that direct planting is practiced in undisturbed lands, so it was needed to design a special furrow opener. In order to obtain a suitable furrow opener this experiment was conducted in rain-fed Agricultural Research Institute in Maragheh. <strong >Materials and Methods </strong > Most of seed planters that are used for cultivation in rain fed conditions are equipped by hoe-type furrow opener. Hoe-type furrow openers have good penetration in hard and dry soils. However, they do not have the ability for direct planting. Hoe-type furrow opener was chosen as a model. Then by changing the geometric form of the depth to width ratio (d/w), the two openers were designed. In the first design, which was called O1 two wings and a narrow blade acting as a coulter were added in front of the hoe-type furrow opener. In the second design, which was called O2, in addition to the O1 modification, furrow opener width was decreased and a disk blade was added for seed sowing (Fig. 1). The performance of O1 and O2 openers were compared with the conventional hoe-type furrow opener (check) in soil bin and in field conditions. At three different forward speeds (1, 1.5 and 2 m.s-1) with 3 replications, the effects of the openers designs of vertical and horizontal soil forces were evaluated in soil-bin conditions. In order to evaluate the performance of the furrow opener in field conditions, an experiment was conducted using a split plot design based on RCBD at 4 replications. Furrow openers formed the main plots and forward speeds formed the sub plots. Each plot size was 22 meters long in two rows for each treatment. After germination of wheat crop, the numbers of seedlings in two rows were counted (along a one meter). After crop maturity, all plots were harvested by hand and grain and biological yield was measured. ANOVA test, uniformity test and mean comparison were conducted by using Genstat software. <strong >Results and Discussion </strong > The soil bin test results showed that opener design and forward speed both have significant influences on the horizontal force (p <0.01). Horizontal force was increased with increasing of forward speeds. The same result was reported by Wheeler and Godwin, 1996 and Astafford, 1979. The lowest horizontal force (average 1.66 kN) occurred at 1 m.s-1 and the highest (average 1.94 kN) occurred at 2 m.s-1 forward speeds. Horizontal force increased in O2 (2.8%) and decreased in O1 (3.4%) compared with the control (average 1.77 kN). Moreover, openers had significant influence on the vertical force (p <0.01). Vertical force values were negative in O1 (average -0.05 kN) and O2 (average -0.07 kN) in comparison with positive value in the control (average +0.01 kN). The effect of forward speed on vertical force was not statistically significant. The field results showed that there were significant differences among the openers in the numbers of seedling, grain and biological yield (p <0.01). The O2 opener (with the average of 48 seedlings per one meter row) had 33% and 24% more seedlings in comparison with O1 and check furrow openers, respectively. Probably, using dick bald in O2 design leads to increased seed germination. Increasing of seed germination by using disk furrow opener as an advantage is reported by Kushwaha and Foster, 1993. The O2 furrow opener would also increase grain yield about 36% compared with both O1 and check furrow openers. <strong >Conclusion </strong > It can be concluded that the newly designed furrow opener (O2) could improve the energy efficiency with increasing crop yield. Hence, O2 furrow opener could be recommended for direct planting in rain-fed farming.