Cannabis Chronicles

We’re slowly working on a more complete medical marijuana growing guide that will include an entire series of essays and entries similar to our previous Guano Guide / Manure Manual as well as our Molasses Manual. As that work progresses, we’ll be including bits and pieces of our research . . .

Table 1. A Selection of Organic Fertilizers for Use in Growing Media^a

Fertilizer Material	Estimated			Rate of Nutrient Release	Salt & pH Effects
	N	P	K
Alfalfa Meal	2.5	0.5	2.0	Slow
Blood Meal	12.5	1.5	0.6	Medium-Fast
Bone Meal	4.0	21.0	0.2	Slow
Cottonseed Mealb	7.0	2.5	1.5	Slow-Medium	Tends to acidify
Crab Meal	10.0	0.3	0.1	Slow
Feather Meal	15.0	0.0	0.0	Slow
Fish Meal	10.0	5.0	0.0	Medium
Granite Meal	0.0	0.0	4.5	Very Slow
Greensand	0.0	1.5	5.0	Very Slow
Bat Guano	5.5	8.6	1.5	Medium
Seabird Guano	12.3	11.0	2.5	Medium
Kelp Meal	1.0	0.5	8.0	Slow	Possibly high-salt
Dried Manure	Depends on Source			Medium	Possibly high-salt
Colloidal Phosphate	0.0	16.0	0.0	Slow-Mediumc
Rock Phosphate	0.0	18.0	0.0	Very Slow-Slowc
Soybean Meal	6.5	1.5	2.4	Slow-Medium
Wood Ash	0.0	1.5	5.0	Fast	Very alkaline, salts
Worm Castings	1.5	2.5	1.3	Medium

(a) Information in the table has been adapted primarily from Penhallegon, Ross. 1992. Organic fertilizer NPK values compiled. In Good Tilth. January. p. 6.; and Rodale Staff. 1973. Organic Fertilizers: Which Ones and How To Use Them. Rodale Press, Emmaus, PA. p. 50.

(b) Cottonseed meal from many sources may be too contaminated by routine pesticide use to be permitted in certified production. Growers should consult their certifiers before using.

(c) The availability of phosphorus in different forms of rock phosphate depends on the pH of the mix, biological activity, fineness of grind, and the chemical composition of the source rock. Precise performance is not easy to predict.

The preceding table was originally sourced from the website for ATTRA - National Sustainable Agriculture Information Service.

The numbers presented in this table should only be considered a rough guide to some manure based fertilizers such as bird and bat guano, who’s nutrient value often depends on a variety of factors.

Here at the Cannabis Chronicles we also have a 3LB day by day grow guide called - Growing LUI with the 3LB’s as well as the 3LB Molasses Manual and the 3LB Guano Guide that were “sticky” threads at Cannabis World and Overgrow.