Unless the worm castings have a fertilizer ratio given on the label, you cannot know how much of any nutrient is being supplied by it.  Many fruits and vegetable crops need high levels of nutrients.  You can find the fertilizer need of each vegetable in our website's Grow It Eat It section, in the crop profiles.  

Here is our website's publication about all the different kind of fertilizer and what nutrients they supply (including worm castings):  http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG42_Soil_Amendments...

 You need to find out the nutrient needs of each crop,  then match it with  the fertilizer that meets that need. 

ECN