How to Kill Weed Seeds at Cow Manure

Although cow manure is a superb source of nitrogen and nutrients for the soil, it is also a source of weed seeds and pathogens, like Escherichia coli and salmonella. Composting the manure in a hot compost pile kills both the weed seeds and bacteria, making it safe to be used in the garden. Despite its being thoroughly decomposed, however, you should always clean your hands carefully after handling any compost or masonry materials.

Building a Compost Pile

A hot compost pile is made up of 2- to 3-inch layers of high-nitrogen brown and green materials. High-nitrogen materials include raw cheeses; white clover (Trifolium repens, USDA zones 3 through 10) and the leaf of different beans, like peas (Pisum sativum). Green materials include new grass clippings, coffee grounds and kitchen scraps. Brown materials include lifeless leaves, garden debris, sawdust, shredded paper and straw. Layer the substances so the pile consists of approximately 25 percent high-nitrogen, 45 percent green and 30 percent brownish or woody substances. Your compost pile should measure at least 3 feet square from 3 feet tall to maximize the heating effects of the decomposing materials.

Cooking the Compost

The compost pile ought to be moist, but not soaking wet, to begin the decomposition procedure. Monitor the stack, measuring the internal temperature daily with a long-stemmed thermometer. When the pile reaches 155 degrees Fahrenheit, turn it to mix the ingredients and allow it to heat up again. Mix the pile with a shovel or pitchfork whenever the temperature reaches 155 degrees Fahrenheit. Most weed seeds and pathogens die at 135 degrees Fahrenheit.

Cooling Down

When most of the organic substances in the compost pile have decomposed, the stack will begin cooling down. If it begins heat too soon, like within the initial two weeks, sprinkle it with water to moisten the components and also support the beneficial bacteria to continue the decomposition procedure. After six to eight weeks, the interior of the stack will be cool or hardly warm. The finished compost ought to be dark and crumbly, resembling rich, loamy soil. Place a tarp over the stack to prevent windblown weed seeds from contaminating the new compost.

Using the Finished Compost

The completely decomposed manure is used directly on existing flower and vegetable gardens, dug into the soil until the growing season starts, and mixed with perlite and backyard dirt for planters and raised beds. Even though the weed seeds and pathogens in the compost are lifeless, garden dirt also contains weed seeds. As you dig the compost to the soil, the weed seeds are subjected to warmth and moisture, both main conditions for sprouting. So, as you have killed the weed seeds in the manure, the garden might still sprout new weeds.

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