Compost aka Black Gold

All of my vegetables and seeds were planted in black compost offered to residents of Dekalb County, Georgia for free. I call it Black Gold because it is so valuable to gardeners. However, although it is a superior growing medium the plants have indicated from the beginning that the compost is anemic - it is nutritionally deficient. I have been augmenting the soil in multiple ways and most plants have responded quickly. Yellowish leaves have turned darker green. A few pants are still yellow by comparison but are producing very high yield. Go figure.