This afternoon, while I was prepping a new bed for garlic, it dawned on me that I should probably pay attention to the types of manure and bedding I was using. Because garlic is a root vegetable, I knew I didn’t want to add high nitrogen to the garden bed. That would stimulate too much top growth, and the energy of the plant wouldn’t be used for making those big, juicy cloves on the bulb.
What I would need is a manure that helps promote root growth. Ideally, this would be a manure high in phosphorus but lower in nitrogen. Potassium, the third micronutrient in the nitrogen-phosphorus-potassium triad, is used by the plant for overall vigor and disease resistance, so it would be OK if the manure was high in this, as well.
One of the benefits to keeping all of our animals in separate housing is that I can pick and choose who has the most appropriate manure for a given garden bed. I can also choose when in the growing season I apply each manure. In general, chicken, turkey, and goat poop is considered “hot” and needs to be composted first. We usually put these down right after harvest and let them sit until we plant again. Rabbit, on the other hand, does not need to be composted before use, so we like to use this during the growing season. Additionally, the bedding mixed in with the manures really helps improve our heavy clay soil.
Below, from the University of Kentucky, are the average numbers for common livestock manures readily accessible to us. The numbers correspond with N-P-K (Nitrogen-Phosphorus-Potassium) and are a percentage of dry weight.
Goat 1.5 – 1.5 – 3.0
Horse* 2.3 – 0.9 – 1.7
Poultry 3.2 – 5.2 – 1.8
Rabbit 2.4 – 1.4 – 0.6
Steer 1.7 – 1.2 – 3.0
If you want to get really technical in determining how much of each type of manure you should add, you can do some calculations. Since growing food isn’t a business for us, it’s not really worth sending all of the manure out for testing then weighing everything before applying it. For home gardens, your ratio can be more of an approximation based on the needs of different crops and what the different manures contain.
What I chose to use for the garlic was the old bedding from the goat yard that also included chicken manure, from when the chickens were housed with the goats. This will be what I use for root vegetables. Once it runs out, I’ll mix the poultry and goat manure together to reach the same numbers. For other crops, below is what I’ll be using where. (Nutrient requirements based on The Vegetable Gardener’s Bible.)
Nutrient requirements when N=high, P=high, K=high: combination of poultry and rabbit manure (or poultry and horse).
When N=high; P=moderate; K=moderate: rabbit manure (or horse)
When N=high; P=low; K=low: rabbit manure (or horse)
When N=moderate; P=moderate; K=moderate: combination of poultry and goat manure (or poultry and steer)
When N=moderate; P=high; K=high: goat manure (or steer)
When N=moderate; P=low; K=low: rabbit manure (or horse)
When N=low; P=high; K=high: goat manure (or steer)
When N=low; P=moderate; K=moderate: goat manure (or steer)
When N=low; P=low; K=low: light on the goat manure (or steer)
Of course, nitrogen, phosphorus, and potassium aren’t the only nutrients plants need nor are they only nutrients found in manure. Manure contains calcium, magnesium, zinc, sulfur, and various levels of other nutrients, as well. Composted manure also contains a lot of beneficial microorganisms that help break down nutrients and make them available to plants. The addition of carbon (bedding) makes the perfect mix of nitrogen and carbon for composting. It wasn’t until we got chickens and started adding their bedding to our compost pile that we were finally able to get it hot. Our livestock manure is actually mixed in with composted kitchen scraps and yard waste to add another level of nutrients.
When it comes to manure and compost, it’s not just about nutrients. Using manure in the garden greatly improves the soil structure, loosening heavy clay soils and increasing water retention in sandy soils. In my opinion, adding compost and/or manure is really the only way to go when trying to improve your soil. You just can’t have healthy, nutritious food without healthy soil.
*Horse manure is commonly available for free or very low cost at boarding stables. Be aware, however, that if the horses are pastured, their manure could be high in weed seeds unless it is properly composted at a high enough temperature.
My friends in college used to call me a Renaissance woman. I was always doing something crafty, creative, or utilitarian. I still am. Instead of arts and crafts, my focus these days has been farming as much of my urban quarter-acre as humanly possible. Along with my husband, I run Dog Island Farm, in the San Francisco Bay Area. We raise chickens, goats, rabbits, dogs, cats, and a kid. We’re always keeping busy. If I’m not out in the yard, I’m in the kitchen making something from scratch. Homemade always tastes better!