Quantitative Recommendation of Phosphorus Fertilizer Based On The Correlation Between Phosphorus of Plant Organs and Soil Phosphorus In Washington Navel Oranges

Abstract AimMany methods have been proposed to recommend plant nutrients, all of which are qualitative and based on the concentration of the element in the soil or leaves. But, in the "Integrated Plant and Soil System" (IPSS) method, there is a recommendation of fertilizer quantified and based on the correlation between concentration of elements in plant and soil organs. MethodsIn this study, 39 Washington Navel Oranges orchards were selected and in each orchard, three trees were chosen and sampled from roots, stems, leaves, fruit as well as the soil around the roots. Sampling was performed in late March and early May for two consecutive years and phosphorus was measured in the samples. After a correlation analysis between "soil properties and phosphorus of plant organs" with soil phosphorus, those factors that had a significant correlation with soil phosphorus were selected. And based on that, there was determined a regression model between them.ResultsAmong all the studied factors, fruit phosphorus had the highest correlation with soil phosphorus. Based on that, two regression equations were obtained by which the required phosphorus can be calculated.DiscussionsSince the physicochemical properties of each element are different from the other, so the leaf alone cannot be a good indicator to determine the nutritional status of all elements. Therefore, it is more logical that the fertilizer recommendation of each element is based on the correlation between the element in that organ of the plant that has the highest correlation with that element in the soil.