Grassy areas within fields provide habitat and hiding places for beneficial insects, spiders and other animals. Strips of grass running through the middle of fields can also be used as convenient access roads for important farm operations.
These grassy strips can be beneficial in the same ways that diverse field margins are helpful (see section on field margins). Strips of grass inside fields or ‘beetle banks’ contain a rich resource of beetles and other insects that can help manage pest without the use of pesticides. During the daytime, long grasses provide protection from predators for beetles. At dusk, many nocturnal predatory beetles, such as tiger beetles, spread out into fields to forage controlling pest populations.
Most of these predatory species are limited by the distance that they can travel. In large fields without grassy strips it is difficult for these species to access the center of the fields although they can access the edges of croplands with field margins. Studies have found that more predatory beetles are in fields that have a high amount of field edge. A single grassy strip through a square field can increase the edge amount by 50%. Leaving grass edges along drainage ditches will also provide habitat similar to beetle banks.
A 3 meter strip of uncut grass (that is not sprayed with any pesticides) will boost the biodiversity of your fields and provide a corridor for wildlife like snakes, toads and rodents, all of which are food sources to important predators like owls and red-tailed hawks.
Grass strips that run perpendicular to the slope of a field can also help reduce run-off and soil erosion. Strategically locating grassy strips near the foot of a slope (bottom of small hill) can efficiently reduce sediment transport off your land.