Written by Brian Smith
The Science Behind Gardening with Manure
As an organic grower I shy away from synthetic, commercially made fertilizers and instead, I use composted manure in both my Cedar Planters and my gardens. I find that the use of manure has given me vibrant and thriving flowers and vegetable plants!
The two types of composted manure that I use are cow and sheep which are available in bags at any garden centre. But the question is, what is the difference between these two types, and which one is best to use for your garden?
Both types of composted manure contain Nitrogen (N) for development of leaves and stems, Phosphorous (P) for strong roots and fruit and Potassium (K) for water regulation and nutrient uptake.. These are usually called the N-P-K content for fertilizer. Cow manure has an N-P-K of 0.25%-0.15%-0.25% while sheep manure has an N-P-K of 0.70%-0.30%-0.90%.
Both sheep and cow manure contain Calcium and Magnesium. Calcium is essential for cell wall production, thus giving good strength for plant support. Calcium deficient plants tend to have distorted growth. Magnesium, is a component of chlorophyll needed for photosynthesis. A lack of magnesium leads to discoloured and brittle leave that shed prematurely.
Cow or Sheep Manure? An Age-Old Question
So which manure is best for your gardens and Cedar Planters raised garden beds? When I first did my research into manure (I am a science geek with a degree in biology) my family and friends thought I had lost my mind. They now understand why I was knee deep in manure research. I thought that the sheep manure would be the best choice BUT after further investigation I proved to myself that I was not completely informed on the matter, and was actually wrong about my initial assumptions!
Sheep manure is the best choice for flowers and above ground vegetable, i.e. tomatoes, beans, peas, peppers etc. This is because it has a high nitrogen content, encouraging above ground leaf grow. Cow manure, with the lower nitrogen content is better for root vegetables , i.e. onions, potatoes etc. as it encourages more of the tuber growth.
This year I will be expanding my vegetable gardening since I’ve tripled the number of Cedar Planters I have. For the root vegetables, I’ll be growing red onions and scallions, as I use a lot of these in my culinary pursuits. For these vegetables I will be using cow manure. For my above ground vegetables, I’ll be growing beefsteak tomatoes, red bell peppers, leaf lettuce, and buttercrunch lettuce. For these I will be using sheep manure. I also have one Cedar Planter devoted to growing herbs such as basil, oregano, parsley, sage, rosemary and thyme (sounds like a Simon and Garfunkel song). My son and daughter-in-law love to come by once a week and do their “grocery shopping” from our Cedar Planters.
Since I have an Irish background, in my gardens I will be planting potatoes along with garlic (using horse manure) and English Cucumbers (using sheep manure). As you might have guessed, I love to cook and prefer to grow my own food!
My wife is the flower person and loves to plant Hibiscus in our 18” x 18” Cedar planters as they remind her of our vacations in the Caribbean. They thrived and lasted into December.
Manure Alternatives & The Best Time of Year to Use Manure!
An alternative to composted manure is a good quality compost which is also rich in Nitrogen, Phosphorous, and Potassium, that will also aid in moisture retention and soil quality. A combination of compost and manure will definitely ensure a bountiful harvest of vegetables and beautiful, abundant flowers!
Lastly, the best time to use composted manure is either early spring or late fall for best results. The sooner I can start harvesting my vegetables and herbs, the sooner I can start doing some Cajun and Italian cooking with a fresh garden salad on the side.
Stay tuned for my next blog on soils ...