Extended Abstract 
1.    Introduction: Vegetables daily is vital for maintaining good health. They provide essential vitamins, minerals, and other nutrients, including antioxidants and fiber. Research consistently shows that individuals who consume at least five servings of vegetables each day have a lower risk of various diseases, including cancer and heart disease. A diet rich in vegetables and fruits can help lower blood pressure, reduce the risk of heart disease and stroke, prevent certain types of cancer, decrease the likelihood of eye and digestive problems, and positively influence blood sugar levels, which can help regulate appetite. Non-starchy vegetables and fruits, such as apples, pears, and leafy greens, may even promote weight loss due to their low glycemic loads, which prevent blood sugar spikes that can trigger hunger. Basil (Ocimum basilicum) is regarded as one of the most important edible crops in the Lamiaceae family. This plant is widely distributed across tropical Asia, Africa, Central America, and South America. Traditionally, basil has been used globally as both a fresh and dried medicinal herb to treat various disorders, offering antispasmodic, carminative, and digestive remedies for conditions such as abdominal cramps, fever, poor digestion, migraines, insomnia, depression, and dysentery. Fertilizers are essential for balancing soluble nutrients in agricultural soil to support the germination and growth of crops, ultimately maximizing yield. However, the continuous application of chemical fertilizers can lead to diminishing returns over time as soil fertility declines and the physicochemical properties of the soil deteriorate, resulting in arid conditions. Over time, it has become evident that chemical fertilizers can degrade soil quality and disrupt microbial communities that are crucial for crop growth.This research was conducted to evaluate the yield, growth, and quantitative characteristics of basil cultivars (green and purple) across three consecutive cuttings under varying plant densities and manure rates in the climatic conditions of Mashhad.
2.    Materials and Methods: An experiment was conducted using a split-split plot layout based on a randomized complete block design with three replications in Mashhad, located in Northeastern Iran under a semi-arid climate. The main plot consisted of three harvests (first, second, and third), while subplots included farmyard manure treatments (0 and 5 t/ha). Sub-subplots were randomized as factorial combinations of three plant densities (30, 40, and 50 plants/m²) and two basil cultivars (green and purple). The following parameters were statistically evaluated across the three consecutive harvests: plant height, number of lateral branches per plant, maximum leaf area index, leaf fresh weight, total dry weight, and total fresh yield. The data were analyzed using ANOVA, and means were compared using the LSD test.

3.    Results and Discussion: The effect of plant density was significant for several parameters: the number of branches per plant, maximum leaf area index, fresh yield of leaves, total fresh weight, and total dry weight of the basil plants. The effect of harvest timing was significant on plant height, number of branches per plant, maximum leaf area index, fresh yield of leaves, and total fresh weight. Additionally, plant height, fresh yield of leaves, total dry weight, and total fresh weight of basil were significantly influenced by the interaction between plant densities and cow manure levels. The interaction between cultivars and harvest timing significantly affected plant height. Furthermore, both total dry weight and total fresh weight of basil were significantly influenced by the interactions between plant density and harvest timing as well as between plant density and cultivar selection. Total dry weight and total fresh weight of basil were significantly affected by the interaction between cow manure and other factors. The results of this research revealed that across three harvests, the application of decomposed cow manure, in conjunction with plant density and cultivar selection, significantly influenced the characteristics of the basil plants. The highest yield was observed during the second harvest, while the optimal total fresh weight and fresh leaf weight were recorded during the initial harvest. Among the three plant densities tested, the most favorable yields were achieved at densities of 30 and 50 plants per square meter, with the highest total fresh weight, dry weight, and leaf fresh weight observed at a density of 50 plants per square meter. When comparing the two cultivars, the green basil variety demonstrated the highest yield.
4.    Conclusion: The results of this experiment indicated that basil cultivars exhibited varying responses to different planting densities and levels of cow manure. In general, the findings suggest that the most effective fertilizer treatment for the green basil cultivar involves applying 5 tons per hectare of manure at a plant density of 50 plants per square meter. These results imply that a sustainable approach can effectively enhance vegetable production by providing essential nutrients and improving soil structure.