بررسی عملکرد ذرت علوفه‌ای (zea maize l.) تحت تاثیر تراکم‌ بوته باقلا (vicia faba l.) و مصرف نیتروژن در سیستم بدون خاک‌ورزی

به منظور بررسی تاثیر تراکم بوته باقلا در تناوب و استفاده از کود نیتروژن معدنی بر عملکرد خشک علوفه ذرت علوفه ای، آزمایشی به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار در دو سال زراعی 97-1396 و 98-1397 در مزرعه تحقیقاتی دانشکده کشاورزی و منابع طبیعی دانشگاه محقق اردبیلی به اجرا درآمد. عامل های مورد مطالعه شامل تراکم بوتة باقلا در تناوب (25، 35، 40 و 80 بوته در مترمربع) و سطوح نیتروژن (0، 100، 200 و 300 کیلوگرم در هکتار بر پایه کود اوره) در ذرت علوفه ای بودند. همچنین یک سطح نکاشت از باقلا به منظور مقایسه ی اثر تراکم های مختلف این گیاه بر ویژگی های ذرت علوفه ای در نظر گرفته شد. نتایج تجزیه مرکب نشان داد که اثر تراکم بوته باقلا بر عملکرد دانه، وزن100دانه، عملکرد بیولوژیک، شاخص برداشت و نیز درصد کاهش وزن خشک علف‌هرز در باقلا معنی دار بود، به طوری که بیشترین عملکرد دانه از تراکم 80 بوته باقلا به دست آمد و در تراکم 40 بوته باقلا بیشترین وزن100دانه و شاخص برداشت مشاهده شد. همچنین در این آزمایش، عملکرد خشک علوفه ذرت، عملکرد پروتئین، کارآیی زراعی و کارآیی بازیافت نیتروژن تحت تاثیر اثر متقابل تراکم بوته باقلا و کاربرد کود نیتروژن قرار گرفت. بیشترین عملکرد خشک علوفه ذرت علوفه ای از تیمار تراکم 40 بوته باقلا+200 کیلوگرم نیتروژن در هکتار به دست آمد که نسبت به تیمار شاهد افزایش 155 درصدی نشان داد. به طور کلی نتایج نشان داد که قرارگیری باقلا در تناوب با ذرت علوفه ای می تواند از طریق کاهش مصرف کود نیتروژن، باعث افزایش عملکرد خشک علوفه، بهبود کارآیی زراعی و بازیافت نیتروژن نسبت به سیستم تک‌کشتی در ذرت علوفه ای گردد.

study of forage corn (zea maize l.) yield as affected by faba bean (vicia faba l.) density and mineral nitrogen in no-till system.

introduction1 nitrogen fertilizers are commonly used to increase economic performance in corn production. however, it should be noted that nitrogen added to the soil in crop ecosystems is not fully available to the plant and may be leached. in this context, many studies have investigated various crop production methods to improve soil health and reduce soil nitrogen losses. crop rotation and no-till may be an appropriate method to improve soil health and increase soil organic carbon and total nitrogen. in this experiment, it was assumed that growing faba beans in rotation with forage corn and applying sustainable agriculture can greatly reduce the need for nitrogen fertilizer in corn and increase nitrogen use efficiency compared to monoculture corn. the objective of this experiment was to determine the appropriate plant density of faba bean and its effect on crop rotation with forage corn, and to evaluate the nitrogen fertilization efficiency of corn. materials and methods a two-year experiment was conducted in 2018-2019 as a factorial experiment based on a randomized complete block design with three replicates at the research farm of the faculty of agriculture and natural resources, university of mohaghegh ardabili, ardabil, iran. the experimental treatments were different plant densities of faba bean (25, 35, 40 and 80 plants m-2) and different nitrogen (n) fertilizer rates (0, 100, 200 and 300 kg ha-1) in forage corn. shadan cultivar of faba bean was planted in this experiment and it was harvested manually at the physiological maturity stage. the corn variety was the single cross hybrid 201, which was planted at the density of 80000 plants ha-1 in the residue rows of faba bean. nitrogen fertilizer (as urea) was applied three times at the v5 stage of corn. three corn plants were harvested at the milk stage and then oven dried at 70 °c for 72 h and weighed. traits studied in this experiment were include grain yield, 100-grain weight, harvest index, biological yield and weed control efficiency in faba bean and fresh and dry forage yield, protein yield, nitrogen recovery efficiency, nitrogen agronomic efficiency and nitrogen productivity in forage corn. statistical analysis of data was performed using sas 9.4 software, and significant differences between treatment means were tested using the duncan's multiple range test at p < 0.05. results and discussion faba bean the highest grain yield was obtained at plant density of 80 plants.m-2, 100-grain weight, and hi were observed at plant densities 40 plant.m-2 and the densities of 80 and 40 plants had the highest reduction percentage in dry weight of weeds and biological yield. it seems that an increase in plant density, especially at the beginning of the growing season, results in complete coverage of the soil with plants and reduces the competitive ability of weeds. in addition, with higher plant density, solar radiation on the plant canopy increases, so less light is available for weeds and the germination rate of weed seeds decreases. the result of cultivation shows higher competitive power and the results were obtained. corn our results showed that using faba bean in rotation with forage corn can reduce the need for nitrogen fertilizer. the results of the mean comparisons showed that the highest dry forage yield of corn was obtained at the density of 40 faba bean plants+200 kg n ha-1, representing an increase of 155% compared to the control treatment. corn yield is very sensitive to nitrogen deficiency. on the other hand, using of legumes in crop rotations can improve crop access to nitrogen. addition, the highest protein yield was observed at the density of 40 faba bean plants+200 kg n ha-1 and 35 faba bean plants+200 kg n ha-1. density of 40 faba bean plants+no application of n fertilizer had the highest nitrogen recovery efficiency and nitrogen agronomic efficiency. thus, it can be concluded that the combined application of nitrogen fertilizer and the