ROLLING, PLANKING, AND HOEING 173 



and stealing water that the seeds need. They 

 are so loose and coarse-grained that the seeds are 

 not sufficiently in contact with the soil to absorb 

 enough water from it. Rolling very light soils is 

 not only an aid to germination, but may also in- 

 crease their capacity to hold water, providing they 

 are covered with a mulch afterward. It is rarely 

 necessary or practicable to roll clay soils for the 

 purpose of supplying more moisture to assist ger- 

 mination, but they are often rolled to accomplish 

 other results. 



Making a Mulch after Rolling. Most of the 

 rolling now done is on land that has been seeded 

 to grain or grass, and it is done immediately after 

 the seed has been harrowed in. In a majority 

 of cases the surface is left compact, as it comes from 

 the roller, and remains so through the season. This 

 is a waste of water. A way to secure all the benefit 

 of rolling and avoid all the disadvantages is to 

 make a shallow mulch on the surface after rolling. 

 Rolling compacts from five to twenty-four inches 

 of soil ; if the upper inch or two are loosened into 

 a mulch, the water drawn up from below as a 

 result is prevented from escaping and most of the 

 seeds get the benefit of it as well. This means that 

 whenever the loss of water by rolling is a detri- 

 ment, as on light dry soils, the roller should be 

 followed by a very shallow- working harrow, as a 

 spike-tooth harrow with the teeth slanting back- 

 ward, or a weeder. 



In some parts of the country a brush drag is used 

 for this purpose. This is usually made of six or 

 eight small white birch trees, twelve to eighteen 

 feet long. The butt ends of these are fastened 

 into a 2 x 4 inch end piece, at such a distance 

 apart that the trees lie side by side and cover 



