There are definitive ways of determining nutrient element deficiencies. There are 16 known elements necessary for plant growth (13 of those come from the soil). Six are designated 'macro' elements-needed in large concentrations and seven are 'micro' elements needed in small concentrations. Under various condidtions, some of the macro elements might be dificient; however, in many soil conditions the micro elements are usually not. You can create some deficiencies in some by overapplications of others so 'tinkering' with applications without knowing what you are doing is not a good idea.
Kansas State University
Hunger Signs in Crops, a symposium, prepared by Firman E. Bear et al, published by American Society of Agronomy and National Fertilizer Association, 1949. Describes deficiency diseases in plants and plant nutrition.