A lifelong learner, Valerie Varnuska enjoys brushing up on science and technology in her Westbury, NY home. In addition to enthusiasm for robotics and natural sciences, she is fascinated by large machines. Valerie Varnuska maintains a special interest in agricultural equipment such as combines and plows.
Harrows are large agricultural machines designed to break up the surface of soil just like a rototiller. Farmers use them to prepare the soil for planting, aerate soil, and cover recently sown seeds.
The oldest types of these tools are spring harrows, which use rows of iron teeth to loosen the soil. These antiquated tools must generally be adjusted by hand, and require several passes over the same area for maximum effectiveness. They are similar to chain harrows, which are more commonly used in landscaping.
Roller harrows have rows of large teeth mounted on rollers. They are particularly effective at breaking up clumps of dirt as they spin. Similarly designed disk harrows rely on rows of concave, blade-like discs. These are used to shred up weeds or plant matter remaining from previous crops.