Threshing board

A threshing board, also known as threshing sledge, is an obsolete agricultural implement used to separate cereals from their straw; that is, to thresh. It is a thick board, made with a variety of slats, with a shape between rectangular and trapezoidal, with the frontal part somewhat narrower and curved upward (like a sled or sledge) and whose bottom is covered with lithic flakes or razor-like metal blades.

One form, once common by the Mediterranean Sea, was "about three to four feet wide and six feet deep (these dimensions often vary, however), consisting of two or three wooden planks assembled to one another, of more than four inches wide, in which is several hard and cutting flints crammed into the bottom part pull along over the grains. In the rear part there is a large ring nailed, that is used to tie the rope that pulls it and to which two horses are usually harnessed; and a person, sitting on the threshing board, drives it in circles over the cereal that is spread on the threshing floor. Should the person need more weight, he need only put some big stones over it."

The dimensions of threshing boards varied. In Spain, they could be up to approximately two metres in length and a metre and a half wide. There were also smaller threshing boards, as little about a metre-and-a-half long and a metre wide. The thickness of the slats of the threshing board is some five or six cm. Nonetheless, since threshing boards are nowadays custom made, made to order or made smaller as an adornment or souvenir, they may range from miniatures up to the sizes previously described.

The threshing board has been traditionally pulled by mules or by oxen over the grains spread on the threshing floor. As it was moved in circles over the harvest that was spread, the stone chips or blades cut the straw and the ear of wheat (which remained between the threshing board and the pebbles on the ground), thus separating the seed without damaging it. The threshed grain was then gathered and set to be cleaned by some means of winnowing.

Until the arrival of combine harvesters, which reap, thresh and clean grain in a single process, the traditional methods of threshing cereals and some legumes were those described by Pliny the Elder in his Natural History, with three variants: "The cereals are threshed in some places with the threshing board on the threshing floor; in others they are trampled by a train of horses, and in others they are beaten with flails".

In this manner, Pliny refers to the three traditional methods of threshing grain:

The threshing board is a historical form of threshing that can still be seen in some regions that practice marginal agriculture. It is also somewhat preserved as an occasional folkloric and ceremonial practice, to commemorate traditional local customs.

For threshing with the threshing board, firstly one brings the baled stalks to the threshing floor. Some are stacked, waiting their turn, and others are untied and placed in a circle forming a pile of grain that is heated by the sun. Then farmers drag the threshing board over the stalks, first going several times around in circles, and then in figure-eights, and stirring the grain with a wooden pitchfork. Sometimes, this work was done with another kind of threshing implement: a Plostellum punicum (Latin; literally "Punic cart") or threshing cart, fitted with a group of rollers, each with metallic transverse razors. In this first stage, the straw is detached from the ear; much chaff and dirty dust remains, mixed with the edible grain. Every time the work of dragging the threshing board is repeated, the grain is stirred again, moving more straw to the edge of the threshing floor. If too much grain is spread on the ground, it has to be raked and swept in order to make a round mound and, if possible, to remove as much straw as possible.