Effect of chemical fertilizers and vermicompost on the field soil properties and nutrient concentrations of quinoa seed (Red cultivar) in Sistan region

Quinoa (Chenopodium quinoa) seeds are an excellent source of antioxidants, vitamins (B1, B2, C, E), and minerals (K, Fe, and Zn). Considering its nutritional value, the cultivation of quinoa is crucial. This plant can produce high yields in soils with low fertility. Various natural ecosystems are irreparably harmed by the misuse and imbalanced application of chemical fertilizers. In addition, continuous use of these fertilizers without organic fertilizers will degrade the soil's physical, chemical, and biological properties, leading to environmental degradation. The use of organic fertilizers such as vermicompost increases plant yield and improves soil structure by increasing the amount of available water and nutrients to plants, followed by an increase in the soil's organic matter content. In this study, we proposed optimal levels of vermicompost and chemical fertilizers and evaluated their impact on the elemental content of red quinoa and certain soil properties in the Sistan region.Materials and Methods This research was conducted on the research farm of the University of Zabol during the 2019-2020 growing season. The experiment was conducted using split plots in randomized complete block designs with three replications. In this experiment, three levels of vermicompost were considered for the main plot (zero, five, and ten tons per hectare), while four levels of chemical fertilizer were considered for the subplot (25, 50, 75, and 100 percent). To determine the physical and chemical properties of the soil, samples were taken from a depth range of 0 to 30 cm prior to the commencement of tillage. Before planting, triple superphosphate and potassium sulfate fertilizers were added to the soil. Before planting, during the 6-8 leaf stage, and prior to flowering, nitrogen fertilizer derived from urea is applied. After harvest, the proportion of soil organic matter and grain elements was determined. SAS software (version 9.1) was used for statistical analysis and mean comparison . According to the results, the combined effect of vermicompost and chemical fertilizers was significant for all measured properties with the exception of the concentration of soil -soluble potassium (concentrations of N, P, K, Fe, and Zn in grain, and soil organic matter). Compared to the control treatment, the amount of seed elements such as nitrogen, phosphorus, potassium, zinc, and iron as well as soil organic matter increased by 18.71, 48.71, 16.66, 5.97, 50.64, and 11.82%, respectively, when 10 tons of vermicompost was applied per hectare with 100 percent of the recommended chemical fertilizers. Vermicompost had a significant effect on the concentration of soluble potassium in the soil, but the concentration of this element was unaffected by the combined effects of vermicompost and chemical fertilizers. The highest amount of soil-soluble potassium was produced by 10 tons of vermicompost per hectare, which increased by approximately 29.2% compared to the control treatment. In conjunction with chemical fertilizers, 10 tons of vermicompost per hectare increased soil organic matter and quinoa nutrient concentrations. Development of high-nutritional-value crops that can be grown on low-fertility arable land, such as quinoa, can significantly reduce the use of chemical inputs. Due to the favorable climatic conditions, the introduction of quinoa as a plant that grows in the Sistan region will increase the region's crop diversity, sustainable production, farmer incomes, and food security.