Evaluation of Different Levels of Nitrogen Fertilizer and Cow Compost on the Yield and Nitrate Uptake of Allium hirtifolium in FereydunShahr Region

 Iranian shallot, scientifically known as Allium hirtifolium Boiss. is a perennial plant of the Allium genus and native to Iran. The Allium genus has many antioxidant properties due to its being rich in organic compounds of sulfur and phenol. The shallot is used to treat rheumatic and inflammatory pains, soothe superficial wounds, treat some stomach diseases, be antispasmodic, and also as a spice and flavoring in some foods. Considering the health benefits of shallot and its application in the food industry, shallot corms are harvested from the natural resources in different stages of growth. Therefore, it is necessary to preserve the natural habitats of shallot and also supply the market demand for this plant. It appears that the cultivation of shallots within agricultural systems could serve as a significant strategy for meeting the demands of the expanding global market. Furthermore, shallots are known for their low water requirements, making their cultivation a focal point in Isfahan province in recent years. Additionally, this crop stands out as a high-income generator in the region. Despite its economic potential, there has been limited research into optimizing the growth conditions for this valuable plant. Hence, this study aimed to explore the impact of urea and cow compost on the yield of Iranian shallots in the Fereydun Shahr region, focusing on the uptake of nitrogen, phosphorus, potassium, and nitrates.
 
 This research was carried out in the crop year of 1400-1401 in a field with an area of 300 square meters (32° 55' 53" N, 49° 56' 43" E) located in Fereydunshahr city of Isfahan province. The experiment was conducted according to a completely randomized design. Factorial arrangement of experimental treatments including two fertilization factors (urea and cow compost) was used. Plots with dimensions of 2 × 3 meters were created with a distance of 50 cm between the rows. The treatments were considered as urea fertilization at four levels (0, 120, 240 and, 360 kg ha-1) and cow compost treatment at three levels (0, 40 and, 60 tons ha-1). After plotting and applying cow compost treatments, shallot corms were planted at a depth of 10 to 15 cm in November 1400. Urea fertilizer treatment was applied in two stages, the first stage when the plant germinated (mid-April) and the second stage before flowering (second half of May). All treatments were applied in 3 replications. It should be noted that the treatments in this research are shown as 0-0 (control), 0-40, 0-60, 120-0, 120-40, 120-60, 240-0, 240-40, 240-60, 360-0, 360-40 and 360-60. The corms were harvested in June 1401 and the fresh and dry yield of the shallots was determined. The amount of nitrogen, phosphorus and, potassium in shallots was measured. Nitrate concentration was also measured in the harvested corms based on the Iranian national standard No. 4106. The nitrogen, phosphorus and, potassium uptake by shallots was obtained from the product of yield and the concentration of these elements. Results were analyzed using analysis of variance (ANOVA) procedure and the means were compared using the protected least significant difference (LSD) test at р < 0.05 probability level using SAS 9.3 software.
 
 The results showed that the combined use of chemical fertilizer (urea) and cow compost has a significant effect on the shallot yield increment, as the highest yield was obtained in the combined treatment of urea fertilizer 240 (kg ha-1) and cow compost 40 (ton ha-1) application. Although the highest nitrogen concentration and uptake were observed in the treatment of 360 (kg ha-1) of urea along with 60 (ton ha-1) of cow compost, it was not significantly different from the treatment of 240-40 (the treatment with the highest yield). In general, the concentration of shallots nitrate was much lower than the permissible limit according to the national standard of Iran No. 16596. The highest nitrate concentration (24.63 mg kg-1 of fresh weight) was observed in the combined treatment of 120 (kg ha-1) of urea and 60 (ton ha-1) of cow compost application (120-60), which was significantly higher than other treatments. On the other hand, the concentration of shallots nitrate in the 240-40 treatment was significantly lower than the treatments of 360 kg of urea per hectare along with 40 or 60 (ton ha-1) of cow compost.
 
 According to the results, to achieve the best yield, the most suitable level of urea application was 240 kg ha-1 and the best level of cow compost was 40 ton ha-1. It seems, utilization more amounts of urea or cow compost will only cause additional costs to the farmer and a waste of capital. Moreover, it can increase environmental pollution and nitrate concentration of product, which cause to quality decrement.