Master Nursery® Bumper Crop® Organic Soil Builder is a soil building blend of manure and high organic nutrient content of shellfish compost, dark, rich earthworm castings (adds minerals and biology), kelp, peat, aged bark, and lobster – inoculated with endo and ecto michorrizal fungi to improve root function. The lobster body provides a lot of Nitrogen, and the shells breakdown to release a lot of calcium, the #1 ingredient that plants need. Bumper Crop® Soil Builder is an all-purpose, pre-fertilized planting and garden soil amendment. This product excels as a nutrient rich top dressing and mulch. OMRI Listed for organic use.