اثر جايگذاري كود نيتروژنه بر محتواي نيتروژن برگ و عملكرد ذرت دانه‌اي

The Effect of Nitrogen Fertilizer Placement on the Yield and Nitrogen Content of the Leaf in Corn

در این تحقیق، مناسب¬ترین روش كوددهی از منبع كود اوره (پخش سطحی كود، ریزش كود در وسط جویچه، كودكاری نواری یك طرف گیاهچه و كودكاری نواری دو طرف گیاهچه) و مقادیر آن (30، 60 و 90 كیلوگرم نیتروژن خالص از منبع كود اوره در هكتار)، بر عملكرد ذرت دانه‌ای كه بصورت سرك در زمان در زمان 7 تا 9 برگه‌ شدن ذرت، به گیاه داده شد، مقایسه شدند و علاوه بر آن مقدار 90 كیلوگرم نیتروژن خالص در هكتار نیز در زمان كاشت بطور یكسان در تمام تیمارها مصرف گردید. این پژوهش به صورت طرح آزمایشی بلوك¬های كامل تصادفی با سه تكرار و به مدت دو سال اجرا گردید. نتایج حاصل از اجرای دو سال طرح، نشان داد كه روش كوددهی هیچ اختلاف معنی‌داری در سطح احتمال 1% بر روی ارتفاع بوته، ارتفاع بلال و درصد چوب بلال نداشت، اما در سطح احتمال 1% بر عملكرد خالص (عملكرد دانه با رطوبت 14%) و در سطح احتمال 5% بر وزن 1000 دانه اثر معنی‌داری داشت. همچنین اثر مقدار كود نیتروژنه نیز در سطح احتمال 1% بر صفات: ارتفاع بوته، ارتفاع بلال و درصد چوب بلال معنی‌دار نبود اما بر عملكرد خالص و وزن 1000 دانه در سطح احتمال 1% معنی‌دار بود. اثر متقابل روش– مقدار نیز در سطح احتمال 1% بر صفات ذرت و وزن 1000 دانه معنی‌دار نبود اما در سطح احتمال 5% بر عملكرد خالص ذرت دارای اختلاف معنی‌دار بود. مقایسه میانگین¬ها نیز نشان داد كه اگر چه تیمار كودكاری در طرفین گیاهچه به میزان 90 كیلوگرم نیتروژن خالص در هكتار عملكرد ذرت را به 92/10 تن در هكتار رسانید ولی با تیمار كودكاری یك طرف گیاهچه به میزان 60 كیلوگرم كه عملكرد آن 463/9 تن در هكتار بود در سطح احتمال 1% اختلاف معنی‌داری نداشت. نتایج تجزیه مقدار نیتروژن موجود در برگ گیاهان در دو سال اجرای آزمایش نشان داد كه اثرروش كوددهی بر مقدار نیتروژن در برگ گیاهان معنی‌دار بود.

Introduction: Corn is one of the most important agricultural products withhigh consumption different forms of usage asfood and fodder. Corn yield and its cultivation needs improvement especially in developing countries. In conventional fertilizing methods with centrifuge machines or hand fertilization, parts of the fertilizer lost through volatilization, leaching and weeds absorption. Leaf burning is also reported in this method. Fertilizer placement in bands is a method that does not show these disadvantages and improves fertilizer use efficiency for the crop. Therefore using new machines and new methods for fertilizing the crop,the cultivation area and mean of yield productioncan improved, for example the yield of corn in this research. Material and Methods: This research was conducted in Lak Lak research farm in Asadabad district. Moldboard plowing plus disking was used for bed preparing the seeds anda 4 rows crop planter was used for planting the seeds. For treatments conducting Combination machine that had designed in thisresearch station workshop was used. This machine was able to place Urea fertilizer with different methods (fertilizer drilling in the rills, fertilizer placement in one side and two sides of plants). The variety of corn that used for this experiment was SC704 with65000 plants in one hectareas plant density. After soil sampling nitrogen, phosphorous and potassium fertilizers and other fertilizers demands by means of soil testwere determined. Half of the nitrogen was used at planting time from source of urea and the other half was used as top dressing duringgrowth season due to treatments as follow: 90 kgha-1 nitrogen as broad costing 60 kgha-1 nitrogen as broad costing 30 kgha-1 nitrogen as broad costing 90 kgha-1 nitrogen as drilling in the rills 60 kgha-1 nitrogen as drilling in the rills 30 kgha-1 nitrogen as drilling in the rills 90 kgha-1 nitrogen as band placement in one side of the plants 60 kgha-1 nitrogen as band placement in one side of the plants 30 kgha-1 nitrogen as band placement in one side of the plants 90 kgha-1 nitrogen as band placement in two sides of the plants 60 kgha-1 nitrogen as band placement in two sides of the plants 30 kgha-1 nitrogen as band placement in two sides of the plants The treatments were conducted through 7-9 leaf bearing stage of corn growth. After harvesting, the mean yield of each plot and other data of plant attributes were collected through growth season and leaf samples were collected for nitrogen analysis. All data were analyzed usingmeans of Duncan 's test. Result and Discussion: The results of experiment showed that, fertilizing method had no significant effect on plant height, maize height and percentage of corn cob at 1% level, but had a significant effect on corn yield at 1% level and on the weight of thousand kernels at 5% level. Also the effect of fertilizer amount on plant height, maize height and percentage of corn cob was not significant at 1% level. The interactional effect of method-amount was not significant on the corn attributes and weight of thousand kernels but was significant on the net yield of corn at 5% level. Comparison of means showed that although the treatment of fertilizer placement in two sides of plants with the amount of 90 kgha-1net nitrogen produced 10.98 tha-1corn yield but its difference with one side fertilizer placement, with the amount of 60 kgha-1 net nitrogen that produced 9.463 tha-1 corn yield, was not significant in 1% level. According to mean comparison table (table 3 and 4) it was clear that using 90 kgha-1 net nitrogen as band placement in two sides of plant row, produced the maximum yield of corn that was in the same group with 60 kgha-1 as band placement in one side of plant row. Therefore the treatment of 60 kgha-1as band placement waspreferred to othertreatments that reduces fertilizer usage and produces good amount of yield. The results of leaf analysis of corn in two years of experiment showed that the treatments effect on nitrogen concentration in corn leaf was significant. Conclusion: Band placement of urea fertilizer from distance of 10 cm of plants and 5 cm in soil depth with amount of 60 kgha-1 as band placement in one side of plant row is recommended for corn through growth season. Band placement of urea is preferred to broadcasting method.