Question: I have several backyard chickens and as a natural result, a lot of chicken manure. Is it worthwhile for me to use it as a fertilizer and how can I safely do so?
Answer: Home gardeners have praised the virtues of manure but recent concerns regarding E. coli contamination have led some to question the practice. Amending the soil with manure is known to improve the texture of the soil and the water retention capability as well as providing nutrients. Problems arise when manure is used incorrectly. Fresh manure contains bacteria that can contaminate your vegetables and cause human disease but with proper composting the bacteria can be killed.
Applying manure adds the primary nutrients, nitrogen, potassium and phosphorous, but only in small amounts. Most gardeners supplement manure applications with additional fertilizers. How-ever, secondary elements, sulphur, calcium, and magnesium as well as micronutrients, zinc, boron, iron, and copper, are also essential and manures are an excellent source of these elements. Manure acts as a slow release fertilizer, providing nutrients over a longer growing period.
Besides providing nutrients, manure is a wonderful soil amendment. Particles of humus from the manure carry a negative electrical charge which is important in holding on to plant nutrients. Sandy soils are electrically neutral which is why nutrients are not held on to very well. Adding manure to sandy soils will help your plants by storing the nutrients in the soil. Lastly, the manure is an important soil conditioner. It acts like tiny sponges helping to retain moisture.
If you want to add manure to your current season of crops, only composted or sterilized manure from a commercial source or home supply should be applied. Non composted manure is best applied in the fall and left to compost until next spring. You can apply non-composted manure now and not plant until fall season crops go in sometime in August. This allows enough time for the breakdown of pathogens. For high risk crops that come in contact with the soil - carrots, onions, lettuce, radishes, and strawberries - you should wait 120 days from the time of application to harvest.
Chicken manure can generate some nasty odors and is best applied in the winter when it will be less offensive. Never use cat, dog, or pig manure in gardens or compost piles. People who are most susceptible to food-borne illnesses should avoid eating raw vegetables from manured gardens. To reduce the risks of contamination all vegetables should be thoroughly washed with a vegetable brush before eating. Peeling vegetables also reduces the chance of unsafe produce.
Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Extension, 6260 Old Harding Highway, Mays Landing, NJ 08330. Email: firstname.lastname@example.org