The effect of nitrogen fertilizers (Urea, Sulfur Coated Urea) with manure on the saffron yield.

In the arid and semi-arid areas of Khorasan, having the low organic matter in the soils, nitrogen is the most limiting factor for the plant growth. This research was done in three regions. Gonabad region, also Broon and Eslamieh areas of Ferdows region, which were done in fifteen farms separately. The experiment was carried out as a randomized complete block design in five farms of each region. There were nine treatments with three replications in each farm. The treatments included were: One control using only (30 Ton/ha) manure as the fertilizer, and the other treatments were; different rates of (23¡34¡46¡57) Kg/ha pure nitrogen from two different sources of Urea, and S.C.U., plus the 30 Ton/ha manure as the fertilizer needed for each experiment. Relative Yield was calculated as: Relative Yield (%) = (Treatment Yield in each Expt.*100/MAX. Yield in that Expt.) Based on the results obtained from data analysis done with the Statistical Analysis System package (SAS), in the Eslamieh area of Ferdows region and in Gonabad region, the effect of nitrogen fertilizer type on the relative yield of saffron were nonsignificant, and the effect of N-fertilizer amount was significant at (α = 0,01). But in the Broon area of Ferdows region non of the factors had a significant effect on the saffron yield. It seems from the results obtained that, saffron response to the Nfertilizer is based on the different areas, which will be different. Meanwhile, if %O.C. and NO3-N of soils are low, we can use 46 Kg/ha of pure nitrogen from both (Urea, and S.C.U) sources plus the (30 Ton/ha) manure, and expect the saffron yield increase compare to the control treatment. Nitrogen amounts higher than (57 Ton/ha), if are not reducing the yield, but will not increase yield significantly. Investigating the effect of higher rates of nitrogen above (57 Kg/ha ), and also the application time and type of N-fertilizer could be good topics for future research.