Ingredients
Bat guano is the accumulated excrement of cave-dwelling bat colonies — deposits that can reach depths of 100 feet in caves across Indonesia, Jamaica, Mexico, and the Philippines. What separates bat guano from every other animal manure is the cave environment itself: low moisture, stable temperatures, and microbial activity slowly concentrate nutrients into one of the most potent natural fertilizers ever discovered.
Bat guano varies dramatically based on the bat species’ diet. Insectivorous bats (those eating moths, beetles, and mosquitoes) produce guano with a high-nitrogen analysis, typically around 10-3-1 NPK. Frugivorous bats (fruit-eating species) produce a high-phosphorus guano with analysis closer to 3-10-1. The cave aging process further concentrates these nutrients as volatile nitrogen compounds off-gas over centuries, shifting older deposits toward phosphorus dominance.
Organic growers use bat guano because it delivers nutrients in both immediately available and slow-release forms. The fresh guano fraction dissolves quickly in soil moisture, providing fast-acting nitrogen or phosphorus. The aged fraction — mineralized over decades in the cave — releases nutrients gradually over 4-8 weeks as soil microbes break down the crystallized mineral matrix.
The NPK analysis of bat guano depends entirely on species and deposit age. Daley Organics selects high-phosphorus bat guano for our fertilizer blends, typically analyzing at 1-10-0.2 or similar phosphorus-dominant profiles. This complements our sea bird guano (nitrogen-dominant) to deliver both macronutrients from natural animal sources.
Beyond NPK, bat guano contains meaningful concentrations of calcium, sulfur, and trace minerals absorbed through the insect food chain. The microbial diversity within bat guano is also significant — studies have identified over 1,000 bacterial and fungal species in cave deposits, many of which are beneficial decomposers that accelerate organic matter breakdown in soil.
Sea bird guano (covered in our companion article “The Guano Wars”) and bat guano serve different functions in the Daley Organics fertilizer blend. Sea bird guano delivers high nitrogen (12-11-2 typical) for vegetative growth — leaf expansion, stem elongation, and protein synthesis. Bat guano delivers high phosphorus (1-10-0.2 typical) for root development, flowering, and fruiting.
The pairing is intentional: by including both guano sources, Daley’s Mix and our standalone fertilizer blends deliver nitrogen from one natural animal source and phosphorus from another, each with distinct release kinetics that overlap to provide continuous nutrient availability over the growing season.
Bat guano is a component of the 25-ingredient complete organic fertilizer found in Daley’s Mix ($140/yd), Premium Soil Mix ($130/yd), Grow Blend 5-4-2, and Bloom Blend 2-7-7. The high-phosphorus profile makes it especially critical in the Bloom Blend, where the 2-7-7 analysis depends on concentrated phosphorus sources to support flowering and fruiting.
At our Grants Pass soil yard, bat guano is blended with bone meal, fish bone meal, and sea bird guano as part of the phosphorus fraction — multiple sources with different release timelines ensure plants never experience phosphorus deficiency during the critical flowering window.
For top-dressing established plants, apply 1-2 tablespoons per plant at the drip line every 4-6 weeks during the growing season. For soil incorporation, mix 2-3 lbs per 100 square feet into the top 4-6 inches before planting. Bat guano also makes an effective compost tea ingredient — steep 1 cup per 5 gallons of water for 24-48 hours with aeration for a phosphorus-rich foliar feed.
Bat guano is one of the more expensive organic amendments, typically $15-25/lb retail. Using it as part of a multi-ingredient blend (as Daley Organics does) distributes the cost across the total mix while still delivering its phosphorus and microbial benefits at effective concentrations.
Common Questions
Bat guano NPK varies by species. Insectivorous bat guano typically analyzes at 10-3-1 (nitrogen-dominant). Frugivorous and aged cave bat guano analyzes at 1-10-0.2 or similar (phosphorus-dominant). Daley Organics uses high-phosphorus bat guano to complement high-nitrogen sea bird guano.
Sea bird guano delivers high nitrogen (12-11-2 typical) for vegetative growth, while bat guano delivers high phosphorus (1-10-0.2 typical) for root development, flowering, and fruiting. Daley Organics uses both in the 25-ingredient fertilizer blend for complete nutrient coverage.
Yes. Bat guano is approved for organic production by OMRI and NOP standards. It delivers nutrients in both immediately available and slow-release forms without synthetic processing. Wear a dust mask when handling dry bat guano to avoid inhaling spores.
For top-dressing, apply 1-2 tablespoons per plant at the drip line every 4-6 weeks. For soil preparation, mix 2-3 lbs per 100 square feet into the top 4-6 inches before planting. For compost tea, steep 1 cup per 5 gallons of aerated water for 24-48 hours.
Used In Our Blends
Want the full science behind every ingredient?
Our ingredient library covers all 26 amendments with full descriptions and product cross-references.
