TILLAGE FOR COTTON 103 



plowing usually insures too much air in the seed-bed, caus- 

 ing it to, dry out rapidly. 



It must be kept in mind that the matter of making 

 plant-food available in the soil involves important and 

 far-reaching chemical and biological processes. An im- 

 portant object of tillage is to hasten these processes. 

 It must be remembered also that under favorable condi- 

 tions, considerable time is required for these processes to 

 change the inert, insoluble soil constituents into a form 

 suitable for nourishing the plant. Fall plowing starts these 

 processes to work sufficiently in advance of the planting 

 season to insure the presence of relatively large quantities 

 of soluble food. On most soils such is not the case with 

 spring plowing. 



Another important benefit of fall plowing is that it ena- 

 bles the soil to absorb and hold large quantities of water 

 during the winter months. Unplowed land retains but 

 little water. It also gives whatever organic matter is 

 plowed under sufficient time to be transformed into humus 

 by the time the crop is growing. Undecomposed vegetable 

 matter is of little value in the soil. On the other hand, 

 it has' been shown that a pound of humus will store iip 

 seven and one-half times as much water as a pound of 

 sand and the sand will lose its water by evaporation three 

 and one-half times more rapidly than the humus. A clay 

 soil can store up only about one-fourth as much water as 

 humus and will lose it by evaporation twice as rapidly. 



An excellent practice which is coming into favor among 

 cotton farmers is to plant a winter-growing cover-crop on 

 the land following fall plowing, which prevents the leach- 

 ing of plant-food dinring the winter months, decreases 

 erosion, and increases the amount of vegetable matter 

 in the soil when it is plowed mider in late winter. This 



