عنوان مقاله [English]
To study the imbalanced fertilization and to optimize fertilizer use in canola farms in the north of Khuzestan Province, Iran, we used Compositional Nutrient Diagnosis (CND) and Deviation from Optimum Percentage (DOP) methods. This research covered 30 canola (Brassica Napus) fields during one cropping season (2019) and soil, leaf, and water samples were collected and analyzed, and grain yield was also measured. Nutritional elements including N, P, K, Fe, Cu, Zn and leaf Mn were determined by standard laboratory methods. Yield community were divided into low and high yield groups using the cumulative function of nutrient variance ratio and K-square distribution function considering the intermediate yield of 2882 kg. ha-1. Then, according to the CND system method, the standard norms for N, P, K, Fe, Cu, Zn, Mn and residual elements (Rd) were determined as 3.27± 0.14, 0.83± 0.17, 2.73± 0.2, -1.89± 0.13, -4.23± 0.53, -3.45± 0.3, -3.46± 0.26, and 3.27± 0.14, respectively. The results of CND system method showed that the most limiting factors in yield were K (among macro- elements) and Mn (among micro- elements). In DOP method, the optimum levels of N, P and K were 5.27%, 0.44%, 2.72%, and for Fe, Cu, Zn, and Mn were 313, 37, 77, and 67 mg. kg-1 dry weight, respectively. In this method, the order of nutrient deficiency was revealed as Cu> Zn> Mn> N> Fe> P.