Why manure rules in the garden

Do goats and gardens mix? Members of the community garden at Glastonbury Abbey think so. At this Benedictine monastery in Hingham, Mass., a herd of Nubian goats is kept for cheesemaking. One of the gardeners asked me for details about using the goats' manure on the garden plots.

Nature doesn't discriminate in the alliance between animal manure and soil. From bird droppings to worm castings, it all ends up in the earth, to the benefit of plants that grow there and the health of animals that consume them. But for garden use, people do have preferences as to which animal makes the best poop.

Human waste is problematic because it can transmit disease, as can that of carnivores such as dogs, cats, rats and pigs, which share parasites with humans. For edible crops, vegetarian critters - cows, horses, rabbits, alpacas and, yes, goats - are a safer choice. Best among them are ruminants such as cows, sheep, goats and deer. With their multiple stomachs they essentially chew and re-chew their food, breaking down weed seeds that could spread to the garden.

Still, most gardeners use whatever safe manure is at hand. It can be spread fresh on a fall garden to break down over the winter and then be tilled under. (The rule of thumb is to wait 120 days after spreading before harvesting crops that touch the soil, like carrots or lettuce, and 90 days for tall ones that don't, like corn.)

But the ideal practice is to compost it first. This should take place in a large pile where legions of bacteria will break it down into available nutrients for plants.

Manure generally arrives mixed with the straw or wood chips used as the animals' bedding - these serve as a carbon source to balance the high nitrogen content of the manure when composting.

The activities of all the bacteria involved in composting give off heat. You can often see the heat rising as steam from an active heap on a cool morning. So fresh manure definitely needs to be composted for some time, lest it burn the plants. We've found that manure from horses bedded on straw, as opposed to wood chips, shavings or sawdust (that are slow to break down) has more available nutrients and grows better crops. Straw also absorbs urine, and keeps the potassium it contains from running off.

You can also add manure to a compost pile composed of other organic ingredients such as spent crops, grass clippings, kitchen wastes and farm hay.

Either way, the practice is the same. The pile will heat up initially, then cool down. After that, if you turn it inside out with a garden fork, it will heat up and cool again. At that point it should look like rich, dark soil with no original ingredients visible and no smell. Then it's ready to use. (You can even make manure tea with finished compost by steeping it in water, then pouring it on the garden.) If you're not sure it's ready, you can purchase a compost maturity test kit from Woods End Laboratory in Mount Vernon, Maine.

So go for the goats, mischievous creatures though they may be. You'll need a really good fence around them. Or the garden. Or both.