The way the leaves were yellowing actually resembles more of a nutrient lock out. So that is a ph problem. Nute burn looks like burnt spots on the leaves right from the beggining. in other words burns do not turn the leaves yellow. The leaves will be green with brown dried spots. A defiency basically just changes the color of the leaves. Both of these issues are very treatable.
So that said, have you checked your ph?
An organic soil will be ph balanced and that is crucial for survival. Often times with a good organic soil you don't even have to add any nutes untill you go into flower time.
Good job on the new soil, you should a great improvement real soon.
I am new at this as well, but I have done a fair share of killing starts. My first grow began in august and 20-30 dead plants later I had one that survived all my mistakes and she turned out to be whimpy, whimpy, whimpy. It was a hydro recirculating system that I built and now will toss because I started a soil grow last night.
Any way, keep us posted
10lbs per 1000sqft isn't terribly helpful ya know? 
