A windrow is a row of cut (mowed) hay or small grain crop. It is allowed to dry before being baled, combined, or rolled. For hay, the windrow is often formed by a hay rake, which rakes hay that has been cut by a mower machine or by scythe into a row, or it may naturally form as the hay is mowed. For small grain crops which are to be harvested, the windrow is formed by swather which both cuts the crop and forms the windrow.
The term windrow is also used to indicate a grouping of fossils that have been deposited together as a result of turbulence or wave action in a marine / water environment. Fossils of like shape and size are commonly found grouped or sorted together as a result of separation based on weight and shape. These groupings are termed windrows or gyres.
By analogy, the term may also be applied to a row of any other material such as snow, earth, etc. In the case of snow, windrows are created by snow plows as they plow streets. The windrow may block driveways. Some municipalities have windrow removal service where a smaller plow goes to each individual driveway to clear the windrow. Most cities simply make the home owner clear the windrow to their own driveway. A few cities will plow the windrow to the center of the street, blow the snow into trucks, and haul it away. Windrows made of snow are also called berms or more commonly, snow banks. A windrow can also be the build-up of material on the edge of newly graded earthworks and dirt roads, or it can be a heap of road-building material laid down by a dump truck for collection by a paving machine.
Windrows of seaweed etc. also form on the surface of lakes or seas due to cylindrical Langmuir circulation just under the surface caused by the action of the wind. Windrows of soil are often used in large scale vermicomposting systems. Municipalities that collect raked-up leaves ask that their citizens rake their leaves into windrows along and above the curb.
Where garden waste (leaves, branches and grass for example)and other biodegradable materials are shredded and mixed and placed into rows for large scale composting are also known as windrows.