How Many Chickens Do I Need on My Garden Bed for Optimal Manure?

Reader Contribution by Troy Griepentrog

How many chickens do I need to keep on winter garden beds to leave the optimum amount of manure for next season’s crops without “overfertilizing” with chicken manure?

Chicken manure is high in nutrients, so it makes a great natural fertilizer for your garden.

According to Commercial Meat and Egg Production, industrial hens produce about a quarter pound of manure per day. That number was calculated from the amount of feed consumed by the hens.

But because these souped-up hybrids are bred for maximum production (under controlled environmental conditions), they consume more feed than heritage breeds — and probably produce more manure.

Eliot Coleman tells us that one of his reference books from the early part of the 20th century, Morrison’s Feeds and Feeding, says that 200 chickens (presumably pre-industrial chickens) produce about 8,500 pounds of manure per year. That works out to about 0.116 pounds of manure per chicken per day, or about half of what modern sources estimate for industrial birds. Coleman estimates that four chickens per 200 square feet of garden for three months is optimal.

Robert Plamondon suggests that 50 to 100 hens per acre (per year) is optimal. This is the equivalent of four chickens per 200 square feet of garden for one month. His source is Poultry Breeding and Management by James Dryden.

So, depending on your soil and growing conditions, you can keep three or four hens in a 200-square-foot area of the garden for up to three months.

But you should also consider removing the chickens before you plant the area, to allow time for the manure to decompose a bit — and levels of any harmful bacteria to decline. Woods End Laboratories has done research that shows that it takes 30 to 120 days for E. coli in soil to be reduced to background levels.

Troy Griepentrog, associate editor