A uniform grass turf is hard to accomplish. Consistent work is required to keep a lawn free of weeds. Unwanted grass in a turf is also a major bother. Other species from the desired turf ruin the uniform look of the lawn due to leaves being shaped differently. Some grasses may be hardier than the desired turfgrass, causing patches of brown as grasses fight for resources. Killing grass does not require chemicals, but can be done organically by cutting out one resource grass cannot do without: sunlight.
Cut the grass in the area of the unwanted grass as short as possible to weaken the plant recommends Gardening Know How.
Lay newspaper over the grass you wish to remove 10 sheets thick, and then wet the newspaper.
Cover the newspaper with a 4-inch layer of wood chips to keep the newspaper from blowing away and to retain the moisture. Water the wood chips to make them heavier. Heat from the sun will warm the wood chips choking the grass underneath.
Check under the newspaper in two to three weeks to see if the grass has died and is decomposing. Do not remove the newspaper too soon as grass will revive. Pull dead grass once it has died.