Evaluation of nutritional balance in peach orchards through deviation from optimum percentage (DOP) method

Nutritional balance is an important factor in improving the yield and quality of horticultural products. In this regard, an assessment of soil fertility, determining optimum fertilizer need and an analysis of nutritional balance in peach orchards are essential. Foliar analysis is a suitable method for evaluating the nutritional status of peach orchards. The method of deviation from optimum percentage (DOP) is a new and easy method compared to the diagnosis and recommendation integrated system (DRIS) method in the interpretation of foliar analysis and its index for individual nutrients is easily calculated. Leaf samples were collected from 61 peach orchards throughout the province during July 2009 and 2010 and analyzed for N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu concentrations. The DOP index was calculated for each of the analyzed elements by applying the following general formula: DOP = [(C × 100)/Cref] - 100, where C is the nutrient concentration in the sample and Cref is the nutrient concentration in the high yielding orchards foliar samples. The indices of DOP were computed for the low yielding orchards. The results showed that the average order of nutrients requirement in these orchards is as following: P>Ca>Mn>K>Fe>Cu>Zn>Mg>N.