Also, if you could please put your location into your profile, so we know where you are, that will help. Your climatic conditions - humidity, heat in summer, and especially rainfall all have a bearing on what to amend your soil with. Compost, compost, compost is always a great place to start. Adding calcium if your soil is already alkaline could spell a lot of trouble.
It's also a good idea to have the irrigation water you're using tested for pH and soluble solids, too. I use high pH well water to irrigate my garden in the springtime before it gets rainy here. That well water raises the pH of the soil over time so that some of my plants show the stress. As soon as it starts to rain generously, that corrects itself, thankfully.
