بررسي و مقايسه سناريوهاي مختلف اقتصادي و زيست محيطي از طريق بهينه سازي مصرف سوپرجاذب رطوبت، اسيد هيوميك و كود دامي در زراعت لوبيا (Phaseolus vulgaris L)

Evaluation and comparison of different economic and environmental scenarios for Bean (Phaseolous vulgaris L.) production via optimization of water superabsorbent, humic acid and cattle manure application rate

در سالهاي اخير استفاده از نهادههاي بومسازگار و بهينه‌سازي اين منابع، به‌عنوان راهكاري اكولوژيك مدنظر قرار گرفته و افزايش توليد و بهبود سلامت محصولات مختلف را در پي داشته است. به‌منظور تعيين مقادير بهينة سوپرجاذب رطوبت، اسيد هيوميك و كود دامي در زراعت لوبيا (Phoseolus vulgaris L.) آزمايشي با استفاده از روش سطح پاسخ، در قالب باكس‌بنكن طراحي و در سال زراعي 93-1392 در مزرعة تحقيقاتي دانشكدة كشاورزي دانشگاه فردوسي مشهد اجرا شد. تيمارهاي آزمايش شامل تركيبي از سوپرجاذب رطوبت (در دو سطح 80 و 160‌كيلوگرم در هكتار)، اسيد هيوميك (در دو سطح 4 و 8‌كيلوگرم در هكتار) و كود گاوي (در دو سطح صفر و 30‌تن در هكتار) بود كه با در‌نظرگرفتن سه تكرار براي نقطة مركزي، در مجموع 15‌تركيب تيماري براي مطالعه لحاظ گرديد. نتايج آزمايش نشان داد كه بيشترين مقدار عملكرد دانه در سطوح مياني اسيد هيوميك (6‌كيلوگرم در هكتار) به‌دست آمد، به‌طوري‌كه مصرف اين مقدار اسيد هيوميك عملكرد دانه را به‌ترتيب 15 و 11‌درصد نسبت به سطوح 4 و 8‌كيلوگرم در هكتار افزايش داد. افزايش متعادل مقادير مصرفي كود دامي منجر به افزايش عملكرد مادة خشك شد، بهاينترتيب كه با افزايش مقدار كود دامي از صفر به 15‌تن در هكتار عملكرد مادة خشك 36‌درصد افزايش يافت، ولي افزايش بيشتر كود دامي (از 15 به 30‌تن در هكتار) كاهش چهار درصدي عملكرد مادة خشك را سبب شد. با افزايش مقادير مصرفي سوپرجاذب، ميزان تلفات نيتروژن كاهش يافت، به‌طوري‌كه كاربرد 120‌كيلوگرم در هكتار سوپرجاذب به جاي 80‌كيلوگرم در هكتار از اين كود منجر به كاهش 17‌درصدي ميزان تلفات نيتروژن شد. كارآيي مصرف نيتروژن در سطح 6‌كيلوگرم در هكتار اسيد هيوميك به‌ترتيب 16 و 13‌درصد نسبت به سطوح چهار و هشت كيلوگرم در هكتار بيشتر بود. در سناريوي اقتصادي به‌ترتيب با مصرف 143/83 و 6/14 كيلوگرم در هكتار سوپرجاذب و اسيد هيوميك و 22/12 تن در هكتار كود دامي، عملكرد دانهاي معادل 1613‌كيلوگرم در هكتار به‌دست آمد. در سناريوي زيستمحيطي ميزان تلفات نيتروژن نسبت به سناريوي اقتصادي به‌شدت (95‌درصد) كاهش يافت. از آنجاييكه در سناريوي اقتصادي-زيستمحيطي از ابعاد مختلف به بهينه‌سازي منابع توجه مي‌شود، بهنظر مي‌رسد استفاده از مقادير بهينة منابع در اين سناريو (به‌ترتيب 131/71 و 6/02 كيلوگرم در هكتار سوپرجاذب و اسيد هيوميك و 300‌كيلوگرم در هكتار كود دامي) مناسبترين سطوح نهادههاي مصرفي در اين پژوهش باشد.

Introduction Maintenance of soil fertility as a permanent bed for continuous production of agricultural products is one of the most important issues affecting the sustainability of food production. In order to achieve healthy food production, application of ecological inputs such as cattle manure and organic acids are inevitable. Cattle manure is an excellent fertilizer containing nitrogen, phosphorus, potassium and other nutrients. It also adds organic matter to the soil which may improve soil structure, aeration, soil moisture-holding capacity, and water infiltration. Humic substances are a mixture of different organic compounds that extract from various sources such as soil, humus, peat, oxidized lignite and coal. They are different in molecular size and chemical structure. A little amounts of humic acid increase soil fertility by improving the physical, chemical and biological characteristics of soil. Water super absorbents are water absorbing polymers (they may contain over 99% water). They have been defined as polymeric materials which exhibit the ability of swelling in water and retaining a significant fraction (> 20%) of water within their structure, without dissolving in water content. The applications of hydrogels are grown extensively. These materials have 100% natural structures and do not have any harm for the environment. Development of using super absorbent hydrogels to reduce crises such as soil erosion, frequent droughts or providing food security requires knowledge of their behaviors and performances in the soil. To determine the optimal irrigation water and fertilizer, the use of mathematical models is inevitable. One of the most common methods used to optimize these factors is the central composite design. A central composite design is an experimental design, useful in response surface methodology, for building a second order (quadratic) model for the response variable without needing to use a complete three-level factorial experiment. Considering the importance of bean as the main crop in Fabaceae family and also the lack of comprehensive information in the field of simultaneous optimization of water super absorbent, humic acid and cattle manure, in this study, different economic and environmental scenarios for bean (Phaseolous vulgaris L.) production via optimization of water super absorbent, humic acid and cattle manure application was evaluated. Materials & Methods In order to estimate optimized application rates of water superabsorbent, humic acid and cattle manure in cultivation of bean, an experiment as Box Benken design using Response Surface Methodology, was conducted at Research Farm of Ferdowsi University of Mashhad, during 2013-14 growing season. The experimental treatments were designed considering of the high and the low levels of water superabsorbent (80 and 160 kg.ha-1), humic acid (4 and 8 kg.ha-1) and cattle manure (0 and 30 t.ha-1) using MINITAB Ver. 17 statistical software, as the central point in every treatment replicated 3 times, so 15 treatment combinations were provided totally. Results & Discussion The result showed that the highest seed yield obtained in the middle level of humic acid (6 kg.ha-1), so that application of 6 kg.ha-1 humic acid increased seed yield 15 and 11% compared to the levels of 4 and 8 kg.ha-1, respectively. The moderate increasing of cattle manure amounts led to an increase in dry matter yield, so that by increasing the amounts of cattle manure from 0 to 15 t.ha-1, dry matter yield increased by 36%, but more increasing the amounts of cattle manure from 15 to 30 t.ha-1 led to a decrease in dry matter yield by 4%. By increasing the amounts of superabsorbent, nitrogen losses decreased, so that the application of 120 kg.ha-1 superabsorbent decreased nitrogen losses 17% compared to the level of 80 kg.ha-1. Nitrogen use efficiency in the 6 kg.ha-1 level of humic acid was 16 and 13% more than the levels of 4 and 8 kg.ha-1, respectively. It seems that application of humic acid increased seed yield by improving soil physical properties. Amiri (2015) reported that humic acid and folic acid increased seed yield of Echium amoenum by 32 and 22% compared to control, respectively. The highest and the lowest seed yield of bean (Phaseolus vulgaris L.) obtained in treatments of 80 kg.ha-1 water super absorbent + humic acid and Non-applicaion of water super absorbent and humic acid, respectively. El-Baz et al., (2012) evaluated effect of humic acid on yield and yield components of soybean (Glycine max L.) and reported that the highest seed yield obtained in level of 1000 ppm humic acid. Conclusions In economic scenario, using 143.83 kg.ha-1 superabsorbent, 6.14 kg.ha-1 humic acid and 22.12 t.ha-1 cattle manure, resulted in 1613 kg.ha-1 seed yield. The nitrogen losses in environmental scenario decreased by 95% compared to economic scenario. Eco-environmental scenario attended to different aspects of resource optimization, therefore it seems using the optimized amounts of resources in this scenario (131.71 and 6.02 kg.ha-1 superabsorbent and humic acid and 0.30 t.ha-1 cattle manure, respectively) are the best levels of ecological inputs in this research.