SOWING, in agriculture, the planting of seed for the raising of crops. The scattering of seed by hand is the simplest and oldest method.
The seed must not fall more thickly at one point of the cast than at another, and the standard of seeding per acre must be rigidly adhered to; hence manual-sowing demands considerable skill and experience. It is still preferred in some districts for the sowing of corn crops ; and in some cases the plough is followed by a furrow-presser, the seed falling into the "nicks" made by it, though under ordinary circumstances the face of the field as left in "seams" by the furrow-slices from the plough is in a suitable condition for broadcasting. So well, indeed, is the ploughing done in many countries that broadcasting gives perfectly good results, and broadcasting machines reaching up to I5ft. wide are in com mon use in place of hand-sowing, as these get over the ground more quickly and deposit the seed more regularly.
As early as 1662 a sowing-machine was invented by Joseph Locatelli in Carinthia. In England the early history of mechanical sowing is chiefly connected with the name of Jethro Tull, who about 1730 invented the corn-drill. Cooke's drill brought out in 1783 was the definite precursor of the modern drill. The drill, besides depositing the seed at a uniform depth, sows it in parallel rows at equal distances from one another and thus makes possible the use of the horse hoe and facilitates the suppression of weeds amongst growing crops, the latter advantage being specially marked in the case of root crops. The "cup-feed" and the "f orce feed" are the commonest and most generally useful types. The cup-drill consists of a long box carried upon wheels and divided diagonally into two sections by a partition. The forward section contains the seed which drops through apertures, the size of which can be regulated by slides, to the bottom section. A spindle geared to the ground-wheels by cogs passes longitudinally through the centre of this section and carries disks, round the rims of which are fitted small cups. As the horses pull the drill forward, the spindle and disks revolve and the cups scoop up the seed and pour it into the funnels ; thence it proceeds down a series of tubes or "spouts" and drops into shallow furrows traced by small coulters travelling immediately in front of the streams of seed. The coul
ters can be raised or lowered by levers and are kept down to their work by weights or pressers, which can be regulated according as deep or shallow sowing is required.
In the force-feed type of drill the seed falls through apertures in the bottom of the seed-hopper into funnels, through which extends a shaft carrying bowl-shaped wheels, one for each. These wheels are either spirally-grooved inside or else cogged and serve to feed the seed regularly into the funnels. Instead of coulters, the drill is often fitted with shoes or revolving disks, similar in action to those of the disk-harrow. The tooth and brush pinion, the perforated disk and the chain feed drills, are other types differentiated according to the method by which the seed is "fed" from the hopper and the kind of crop being sown.
Liquid-manure drills distribute chemical manure mixed with water and are often fitted with a seed-box for root seeds, the manure and the seed being deposited through the same spout. Drills are also made in which dry fertilizers may be deposited with the seed in a similar manner.
The wheelbarrow seeder, a long box pierced with openings and carried transversely on a skeleton wheelbarrow, is used for sowing grass seed.
In its general construction this machine is a sulky plough, having a double mould-board, which turns the furrow in both directions. Immediately behind the plough is a sub-soiler for deepening the furrow and penetrating to the moist soil below the surface. A seed-box is mounted on the plough beam, and is pro vided with a feed-plate operated by a shaft geared to one of the wheels. The seed is delivered to the furrow in rear of the mould boards and covered by two shovels fixed behind which turn the soil back into the furrow.