ارتقاي بهره‌وري آب و كارايي مصرف كود در كودآبياري جويچه¬اي نيشكر

Improving Sugarcane Water and Fertilizer Use Efficiency in Furrow Fertigation

در این تحقیق آزمایش¬های كودآبیاری در یكی از مزارع كشت و صنعت نیشكر دهخدا برای افزایش بهره‌وری آب، بهبود مدیریت مصرف كود و كاهش مصرف كود اوره اجراء گردید. آزمایش به¬صورت كرت¬های یك¬بار خرد شده با طرح پایه بلوك¬های كامل تصادفی اجراء شد. تیمارهای آزمایشی شامل سه تیمار تقسیط كود (شامل دو، سه و چهار تقسیطی) در كرت¬های اصلی و سه تیمار سطح كود (شامل 100، 80 و 60 درصد كود اوره) در كرت¬های فرعی بودند كه با روش مرسوم كوددهی مورد استفاده در مزارع كشت و صنعت دهخدا مقایسه شدند. حجم آب مصرفی در طول دوره رشد و برخی صفات كمی و كیفی نیشكر در انتهای فصل زراعی تعیین شد. نتایج نشان دادند كه فاكتور تقسیط تأثیر معنی¬داری در سطح احتمال پنج درصد بر صفات كمی و كیفی نیشكر دارد. به¬طوری كه میانگین همه صفات كمی و كیفی مورد مطالعه در تیمارهای چهارتقسیطی در رتبه اول قرار گرفتند. فاكتور سطوح كودی بجز بر كارآیی مصرف كود، بر بقیه صفات كمی و كیفی تأثیر معنی¬داری نداشتند. اثرات متقابل فاكتور تقسیط و سطوح مختلف كود نیز بر هیچ¬یك از صفات مورد مطالعه معنی¬دار نشد. مقایسه¬ی میانگین صفات مورد مطالعه در تیمارهای آزمایشی و تیمار شاهد نشان داد كه تیمار چهار تقسیطی با 60 درصد سطح كودی در اغلب صفات مورد مطالعه در رتبه نخست قرار گرفت. عملكرد نی، بهره‌وری آب و كارآیی مصرف كود، بهره‌وری آب بر اساس شكر تولیدی در این تیمار به¬ترتیب 2/98 تن در هكتار، 4/5 كیلوگرم نی بر مترمكعب آب مصرفی، 6/467 كیلوگرم نی بر كیلوگرم كود و 581/0 كیلوگرم شكر بر مترمكعب آب مصرفی تعیین شدند. این مقادیر در تیمار شاهد به¬ترتیب، 8/81 تن در هكتار، 5/4 كیلوگرم نی بر مترمكعب آب مصرفی، 7/233 كیلوگرم نی بر كیلوگرم كود و 396/0 كیلوگرم شكر بر مترمكعب آب مصرفی بدست آمدند.

Introduction: Application of simultaneous nitrogen fertilizer and water as fertigation in surface irrigation systems is developing. In fertigation is possible to increase water and fertilizer use efficiency and it allows growers to apply nutrients in split and small amounts throughout the season in response to crop needs. In this study, sugarcane furrow fertigation experiments is carried out in Dehkhoda agro-industry company to improve fertilizer management, water and nitrogen use efficiency, and reduce urea fertilizer consumption. Materials and Methods: Large scale furrow experiments were conducted on a plant field. Field experiments were carried out as split plot with a complete randomized block design. Experimental treatments consisted of three fertilizer splits (2, 3, and 4 splits) in main plots and three levels of urea fertilizer (60, 80 and 100% of required urea fertilizer) in subplots and compared with the common method (control) used in the agro-industry fields. Experiments were conducted on a 25 hectare field in 250 meter long and blocked end furrows. Irrigation water during the crop season was applied the same for different fertigation treatments and measured using the WSC flumes in each irrigation events. Irrigation interval varied from 8 to 15 days during the crop season. Qualitative and quantitative traits (e.i., stalk height, cane yield, purity, brix, white sugar yield, and water, fertilizer, and sugar use efficiency) at harvest were measured and analyzed using the MSTATC software. Results and Discussions: A total of 21 irrigation events during the growing season were measured. Average water consumption in each irrigation event was 865 cubic meters per hectare. Total applied irrigation water during the growing season was 18,155 cubic meters per hectare. Results showed that fertilizer split factor significantly affected the qualitative and quantitative traits at a 5% level of significance. So that, all qualitative and quantitative traits in four split treatments were significantly (P <0.05) higher than two and three split treatments. Fertilizer levels only affected the fertilizer use efficiency. Interactions between split factor and fertilizer levels on any of the parameters studied were not significant. Mean comparison of the traits among the control and experimental treatments showed that the four split treatment with 60% fertilizer level, significantly (P <0.05) resulted in higher cane height and yield, brix, white sugar yield, water, fertilizer, and sugar use efficiency. Stalk height, cane yield, water, fertilizer, and sugar use efficiency values in this treatment were 294.9 cm, 98.2 ton/ha, 5.4 kg/m^3, 467.6 kg/kg, and 0.581 kg/m^3, respectively. These values in the control treatment were 273.3 cm, 81.8 ton/ha, 4.5 kg/m^3, 233.7 kg/kg, and 0.396 kg/m^3, respectively. Results also confirm that more consumption of urea fertilizer in control and fertilizer level of 80 and 100% treatments did not result in improving the quantity and quality of sugar cane parameters. In most of the studied traits, there was not significant difference between two and three fertilizer split treatments. Due to the difficulty and high cost of fertilizer application in sugarcane fields, application of urea fertilizer in two split will be more effective. Conclusion: High consumption of urea fertilizers increases threat to environmental risks and water pollution. The latter did not result in improving the quantity and quality of sugar cane parameters in this study. Superior of 60% level of the fertilizer treatments means a saving of 140 kg of urea ertilizer per hectare. With an area of about 100 hectares of cultivation of sugarcane in Khuzestan, in addition to environmental issues is meant to reduce the consumption of urea of 12,000 tons per year. It is suggested to conduct such projects for other commercial varieties of sugarcane in plant and raton fields of other agro-industry companies.