Every good gardener worth their salt loves manure. I am over the moon delighted whenever I can get hold of the stuff, because it means that my garden, a lot of which is suburban fill, or hard heavy clay, can get much needed organic matter and nutrients. So in honor of our favorite gardening material, M is for Manure.
Manure is used to add nutrients, beneficial microorganisms, organic matter, and all manner of minerals and trace elements to existing soil, which in turn nourishes the plants we grow, making them more nutritious. It is used to build up the humus level in sandy soils, and to improve clay soils by breaking up the dense structure to allow water and air into the soil for good root growth. It feeds earthworms, dung beetles, good bacteria, and fungi.
While bad soil benefits from anything beneficial you can add to it, many folks might be surprised to learn that not all manure is created equal. I'll walk you through some of the most common types of manure to use in the garden and what they bring to the table, so to speak.
High in nutrients and organic matter. Should not be used fresh as there is risk of it burning the roots of your plants, but works great when dried and composted. Will contain partially digested grass and weed seeds, which could sprout in your garden- proper hot composting will destroy those seeds, and any harmful pathogens. Stable manure can be very volatile, as it also contains urine- let it compost first before using, as it will burn plants when fresh. Relatively low earthy smell. I spread it under my trees and shrubs and they like the energy boost.
Has less nitrogen than other manures, so it can be added directly to soils without damaging plants. It adds plenty of organic matter and beneficial microorganisms. It also contains calcium, magnesium, zinc, sulfur, copper, manganese and sodium, all necessary minerals for healthy garden plants. There is a lower risk of cow manure containing weed seeds, but the level of salt might be higher depending on the cows feed, especially in arid and semi-arid areas. Old cow manure is low to no smell, but fresh cow manure is pretty whiffy- it is not my favorite!
Sheep manure is second only to chicken manure in nitrogen, potassium and sulfur content, making it an excellent slow release fertilizer. The high sulfur contents is good for maintaining soil acidity. Once it has aged and broken down, it contains very few nutrients, but is very high in organic matter. May contain wool dags and hoof clippings. Personal experience finds sheep manure to be relatively low smell, and easy to apply (my potatoes love it!). It is my favorite manure to use, second only to horse manure.
High in nitrogen, making it very volatile ("hot")- it's harmful to plants when fresh, and must be composted first with grass clippings and straw. Very low organic matter, but also is much less likely to contain surviving weed seeds. Can be very smelly if it's left wet, but pretty low to no smell if you keep it dry until you can get it into a compost heap (pertinent especially to those who keep birds).
Rich in nitrogen, potash and phosphorus. Rabbit manure is a "cold" manure, and can be applied directly with no need to age or compost first. Rabbit keepers will often raise worms as well- the worms break the manure down into rich black soil. Slow release fertilizer, with good organic matter and soil building properties. Low smell, but harder to find, unless you raise your own rabbits, or know a local rabbit keeper.
I have been in the process of switching as much of my garden as possible over to no dig, so I've been using a lot of manure, straw and other mulch materials to build the beds up. My goal is to have all the beds converted to no dig by next Spring. I like using horse and sheep manures, mushroom compost, cardboard, newspaper, wheat and pea straw for the layers, and all of my plants in the house garden have benefited from added manure, as the soil here is pretty poor.
I hope you found this informative, and I'll post again tomorrow. Happy gardening!