Effect of Different Levels of Nitrogen, Bio-fertilizers and Nano-nitrogen on Yield and Nitrogen Use Efficiency of Soybean in Darab Region (Fars)

Introduction Soybean is a member of leguminoseae family with average protein percentage of 40%, which needs a large amount of nitrogen fertilizer to get maximum yield. Using biofertilizers, beside chemical nitrogen fertilizers, can reduce proportion of chemical nitrogen demand without any undesirable effect on quantity and quality of its yield. Biological nitrogen fixation of soybean by Rhizobium japonicam can improve nitrogen use efficiency parameters beside its yield. This experiment was conducted with the aim of study the effect of different levels of nitrogen, bio-fertilizers and Nano-nitrogen on nitrogen use efficiency (NUE) and yield of soybean (Glycine max (L.) Merr.) cv. Williamz.Material and Methods A field experiment was conducted as a spilt plot in a randomized complete block design with three replications in 2013 at research center for agriculture and natural resources of Darab, Fars, Iran. Main factor was mineral nitrogen at three levels (zero, 75 and 150 kg N ha-1 ) and sub plot was nitrogen source at four levels (Rhizobium japonicum, nano-nitrogen, nitroxin and control). Rhizobium japonicum bacteria was inoculated in rate of 125 gr per 50 Kg seeds, nitroxin in rate of 0.5 L per 9 Kg seeds, and nano-nitrogen in rate of 10 L ha-1. The experimental plot dimensions were 2 x 4 m consisting of 4 rows of cultivated soybean 50 cm apart. The seeds were planted 5cm apart on each row. A furrow irrigation system was employed during experimental period. After the physiological maturity the experimental plots were harvested and yield, yield components, protein, protein yield, seed nitrogen content at ripening stage, nitrogen use efficiency (NUE), nitrogen utilization efficiency (NUTE), nitrogen uptake efficiency (NUE) and nitrogen harvest index (NHI) were measured.Results and DiscussionThe results showed that the interaction of nitrogen and nitrogen source was significant for grain yield, harvest index, nitrogen percentage in the grain ripening phase, seed protein and protein yield. Mean comparison showed that the highest grain yield (2018 kg ha-1) obtained from application of 75 kg N ha-1 with Rhizobium application and the lowest grain yield (1476 kg ha-1) obtained from the no nitrogen fertilizer application. The highest seed protein percentage and seed protein yield observed in application of 150 kg N ha-1 with Rhizobium application. The highest nitrogen in the grain (1.51 %) was related to application of 75 kg ha-1 N with nano-nitrogen application. The highest nitrogen content of shoot in harvesting stage was achieved by integrated application of 75 kg ha-1 nitrogen and nano-fertilizer nitrogen. The highest nitrogen harvest index (NHI) (77.81 %) obtained from application 150 kg ha-1 N with nano-nitrogen application, maximum nitrogen use efficiency (NUE) (26.90 kg kg-1) was obtained from application of 75 kg N ha-1 and Rhizobium application and the minimum (12.66 kg kg-1) was obtained from application of 150 kg N ha-1 and Rhizobium. Generally, soybean production in Darab region had the best results with the use of 75 kg N ha-1 along with the Rhizobium japonicum application.ConclusionsApplying of biofertilizers beside chemical nitrogen, could decrease chemical nitrogen use without any impact on qualitative and quantitative yield of soybean. According to the results of this study application of half of the recommended amount of nitrogen (75 kg N ha-1) and inoculation with Rhizobium japonicum bacteria (125 gr per 50 kg seeds) had the highest grain yield, harvest index, nitrogen use efficiency (NUE) and nitrogen harvest index (NHI). It seems that combined application of bacteria and chemical fertilizers can improve soybean performance and also reduce its chemical nitrogen demand. Our results suggested that, integrated application of 75 kg ha-1 nitrogen and Rhizobium can be suitable treatment to soybean production in Darab climatee.