بررسي تأثير مصرف تقسيطي كود اوره بر تلفات نيتروژن در كودآبياري جويچه‌اي

آب و خاک  

دوره 30 - شماره 5

نوع مقاله: Original Article
چكيده: كودآبياري به دليل امكان مصرف تقسيطي عناصر غذايي روشي مؤثر براي افزايش كار آيي مصرف آب و كود و كاهش تلفات كودهاي نيتروژني است .در پژوهش حاضر به‌منظور بررسي اثر مصرف تقسيطي كود اوره در كودآبياري جويچه‌اي بر تلفات كود، تحقيقي بر روي ذرت دانه‌اي رقم سينگل كراس ۲۶۰ در مزرعه پژوهشي موسسه تحقيقات اصلاح و تهيه نهال و بذر (كرج) در سال زراعي ۱۳۹۲ انجام شد. اين آزمايش‌ شامل ۷ تيمار به‌صورت يك تيمار پخش سطحي كود و شش تيمار كودآبياري بود و در چهار تكرار انجام گرديد. طرح آزمايش به‌صورت فاكتوريل و در قالب طرح بلوك‌هاي كامل تصادفي اجرا گرديد. فاكتور اول (S) شامل دو سطح تقسيط كود اوره (سه و چهار تقسيطي) و فاكتور دوم (N) شامل سه سطح كودي (۱۰۰، ۸۰ و ۶۰ درصد توصيه كودي) بود. تيمارهاي كودآبياري در نهايت با روش كود دهي سطحي مورد مقايسه قرار گرفتند. كود مورد نياز در تيمار سنتي در دو تقسيط مساوي و به‌صورت پخش سطحي به خاك اضافه گرديد. بر اساس نتايج حاصل از تجزيه واريانس داده‌ها، درصد تلفات نيتروژن از طريق رواناب سطحي، تحت تأثير مقدار كود مصرفي و اثر متقابل آن با تقسيط كود قرار گرفت. بيشترين تلفات نيتروژن توسط رواناب، در سطح كودي ۱۰۰ درصد اتفاق افتاد و تفاوت معني‌داري بين سطوح ۶۰ و ۸۰ درصد توصيه كودي حاصل نشد. از لحاظ درصد نيتروژن باقي‌مانده در خاك، تيمار سنتي با روش پخش سطحي كود، داراي بيش ترين مقدار نيتروژن موجود در خاك بعد از آزمايشات كودآبياري بود. علاوه بر اين در بررسي اثر متقابل تقسيط و مقدار كود مصرفي مشاهده شد كه با كاربرد تنها ۶۰ درصد توصيه كودي طي چهار تقسيط مساوي در طول فصل رشد، مي‌توان ضمن دست‌يابي به عملكرد مطلوب، ميزان آلودگي زيست‌محيطي را كاهش داد.
Evaluation of the Effect of Split application of Urea on Nitrogen Losses in Furrow Fertigation
Article Type: Original Article
Abstract: Introduction: Broadcast fertilization method increases fertilizer losses while results in lower nutrient absorption by plant roots. Fertigation is an effective method to increase water and fertilizer efficiency and to reduce the losses of nitrogen. Moreover, it allows farmers to apply the nutrients in splits and few amounts in response to crop needs. In the present study, a field experiment was conducted to investigate the effects of split application of fertilizer in furrow fertigation on nitrogen losses and corn yield.
Materials and Methods: Field experiments were carried out factorially in a randomized complete block design with four replicates. Experimental treatments were consisted of three fertilizer splits (two, three, and four splits) and three levels of urea fertilizer (60, 80 and 100% of required urea fertilizer), which compared with the common method (broadcasting fertilizer) as used by farmers in the fields. Experiments were conducted on a one hectare field in 120 meter long and open end furrows. During the crop season, Irrigation water was applied in the same way for all fertigation treatments and the third type of the WSC flumes was used to measure the amount of input and output water in irrigation events. Moreover, for determining the indexes of uniformity of water distribution in carrying out fertigation experiments, the amount of infiltration into the soil was calculated using the Kostiakov-Louis equation. The parameters of this equation were determined using the water volume balance method. Injection of Urea fertilizer was done by using 40-liter barrels were placed at the beginning of Furrows. In this study, the injection of fertilizers was applied in the last 10 to 20 minutes of irrigation time.
Results and Discussions: Results showed that water distribution uniformities of low quarter and low half in all tests were very high. Such that the water low quarter distribution uniformities for all treatments were between 90.5 to 98.3 percent and the low half distribution uniformities of water for different treatments were between 94.4 to 99.0 percent. So, according to the high water distribution uniformity and injecting fertilizer in 20-10 minutes at the end of irrigation, it should be stated that the distribution uniformities of fertilizer, used in the experiments, were high too. Statistical analysis showed that nitrogen usage amount and interaction of splitsusage rates of fertilizer had a significant influence on run-off nitrogen losses. The most nitrogen losses were achieved in treatment using 100 percent of fertilization recommendation and there were not significant differences between 60 and 80 percent of fertilization recommendation. It is nothworthy that, in addition to the nitrogen loss by surface runoff, nitrogen deep percolation losses always are also considered. In fertigation treatments, because of high rate of nitrogen injection in short intervals at the end of irrigations, the amount of nitrogen in the surface layer (20-0 cm) was significantly higher than the lower depths and this could led to low percolation losses of nitrogen, but the broadcast fertilization method provided the highest percent of remaining nitrogen in the soil after fertilization, which almost is unusable for plant and in the case of over irrigation or rainfall, the risk of groundwater pollution could be raised. Besides, the results showed that application of nitrogen in 4 splits provided more grain yield compared to the 3 splits level. Also, grain yield of corn increased significantly with increasing nitrogen rate application. The fertigation treatments had better performance of water and fertilizer application efficiencies compared to broadcast fertilization method. The most grain yield was achieved in the fifth treatment by application of 100 percent of fertilization usage recommendation in three splits.
Conclusion: In this study, the effect of furrow fertigation on nitrogen losses and corn yield was studied under different splits and amounts of fertilizer consumption. Eventually, fertigation treatments were compared with traditional treatments (fertilizer broadcasting method). According to the obtained results, evaluate the interactions of the effect of split × N usage showed that, the fourth treatment (60% of fertilizer application in 4 splits) can be suggested, owing to its lower N losses by runoff. In addition there were no statistical significant differences of grain yield between the fourth and fifth treatments (100% of fertilizer application in 3 splits). Consequently, it can be concluded that by the usage of 60 percent of the recommended fertilizer application in four equal splits during the growing season, the potential of environmental pollution will be reduced while achieving optimal performance.
قیمت : 20,000 ريال