Is there an actualy organic Cal nutrient?

• Potsnob is partially right, yes lime is a good source. And yes adding lime improperly (dehyrated kind) could kill the microherd your trying to maintain to ensure your plants roots have all the readily available nutrients in your soil.
  
  I personally use General Organics Ca/Mg+ in my watering when/if needed. Dolomite Lime is what you would want to add not just lime but there are several form of dolomite lime, prilled, rock salt and a small dark grain forms. There is also Soft Rock Phosphate and Rock Phosphate which can help aid in the blending powerful nitrogen guano or blood meal with lime rather that be globally, layers or spikes in application when preparing an organic soil mix instead of losing nitrogen to ammonia gas it helps retain it in the soil and helps Calcium stick to the soil.
  
  Essentially with either dolomite lime prilled or oyster shell (powder) you want a fast acting to treat deficiencies. You want slow release forms of these organic nutrients when you build a "enhanced" soil mix, a.k.a super soil by subcool, layers and spikes by the Rev or make your own High Octane soil mix. Adding dolomite lime period can also cause too much magnesium and that can be problematic for your soil in hardening it and restricting air flow. Horticulture lime is pure calcium. Go easy when applying dry lime in general when mixed with other dry nutrients it can cause a initial reaction that can harm roots. If dry go prilled more soluble then grain type. There is also a type of dolomite that looks like small pieces of rock salt I have used this 1TSP / per gal.
  
  You will not see any deficiencies in my organic soil mix grows for I prepare a soil blend in advanced that will take my ladies from veg to flower. Anything I add is to push her and that is generally a light but balanced blend that does not drop soil PH, this is what you need to watch for in your application of amendments even organic ones can cause lock out if there is a reaction that alters soil PH. When in doubt flush stabilize PH run off to 7. Then wait and feed lightly and monitor soil PH runoff or use a soil PH meter
  
  
  

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Potsnob is partially right, yes lime is a good source. And yes adding lime improperly (dehyrated kind) could kill the microherd your trying to maintain to ensure your plants roots have all the readily available nutrients in your soil.

I personally use General Organics Ca/Mg+ in my watering when/if needed. Dolomite Lime is what you would want to add not just lime but there are several form of dolomite lime, prilled, rock salt and a small dark grain forms. There is also Soft Rock Phosphate and Rock Phosphate which can help aid in the blending powerful nitrogen guano or blood meal with lime rather that be globally, layers or spikes in application when preparing an organic soil mix instead of losing nitrogen to ammonia gas it helps retain it in the soil and helps Calcium stick to the soil.

Essentially with either dolomite lime prilled or oyster shell (powder) you want a fast acting to treat deficiencies. You want slow release forms of these organic nutrients when you build a "enhanced" soil mix, a.k.a super soil by subcool, layers and spikes by the Rev or make your own High Octane soil mix. Adding dolomite lime period can also cause too much magnesium and that can be problematic for your soil in hardening it and restricting air flow. Horticulture lime is pure calcium. Go easy when applying dry lime in general when mixed with other dry nutrients it can cause a initial reaction that can harm roots. If dry go prilled more soluble then grain type. There is also a type of dolomite that looks like small pieces of rock salt I have used this 1TSP / per gal.

You will not see any deficiencies in my organic soil mix grows for I prepare a soil blend in advanced that will take my ladies from veg to flower. Anything I add is to push her and that is generally a light but balanced blend that does not drop soil PH, this is what you need to watch for in your application of amendments even organic ones can cause lock out if there is a reaction that alters soil PH. When in doubt flush stabilize PH run off to 7. Then wait and feed lightly and monitor soil PH runoff or use a soil PH meter​